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A TUNE-UP FOR THE DUAL TURNTABLE

1. In my listening tests I compared the sound of the records with the 4010 Figure 1 shows the spectrum analysis of a segment of Edison Diamond Disc 8378 Teasin played by the Vincent Lopez Orchestra The top line is the L R mode while the lower line shows the result with the LR blend mode at the center position The difference between the two lines is 1dB at all frequencies Again a 10 rotation of the LR blend control did not change the frequency spectrum but I could hear a subtle audi ble effect mostly on swishing sounds at the one o clock position I hate it when I can hear but not see a result My next step was to listen with the blend control at the full right and full x left positions Unlike with the wide groove recordings I heard a difference with the Edisons The left channel was generally 2dB louder It occurred to me that this is just a channel imbalance To test this I replaced the Stanton cartridge with an Ortofon Concorde Pro fitted with a 3 3 mil truncated elliptical stylus The full right and full left spectrums are nearly identical Figure 2 shows nearly perfect channel balance For another test of the channel bal ance thesis I removed the utility amp and connected both turntable channels directly into the 4010 With the Stan ton cartridge listening revealed that the maximum null occurred at the one o
2. If RP is decreased to 9000Q while RK x remains at 100000 the following results are obtained 1 B 0 52632 2 A 14 23221 3 A 1 67621 A Ak 0 882223 5 Ap 0 793987 6 ek 8 82223V 7 ep 7 93987V 8 ik ip 8 8223 10 a Evaluating the characteristics of the i split load phase inverter using feedback theory is a rather simple effort and pro vides a dynamic analysis of the system for example the reduction in distortion generated by the tube is A A or in the i case above about 1 8 The equations 30 31 and 34a on page 330 of the RDHB4 a are accurate when used for their purpose Equation 30 when evaluating changes in plate loading only Equation 31 when i evaluating changes in cathode loading only and Equation 34a when evaluating identi cal changes in plate and cathode loading In each case identical initial plate and cath ode loads are assumed C R Morton Chris Paul responds www audioxXpress com change a single circuit component where as the AM requires only the recalculation of a single expression for each parameter Finally as described in my letter the AM i affords a means of verifying that its derived i expressions are consistent with the original i conservation of current equations for the cir cuit as written down by simple inspection i am unaware of a similar check for N amp FA but differe
3. er Although snug there was plenty of room around the transformer for routing of internal wires and placement of the x VFSMC circuit board i C j x ance hole in the enclosures second plastic endcap adjacent to the on off switch to mount the 2kQ frequency adjustment Next I drilled a 0 25 diameter clear potentiometer Photo 4 Then I drilled a no 8 size clearance countersunk hole the heatsink mounting slot channel in heatsink mounts up against the mount ing slot and is secured in place by an 8 x 32 x 5 8 Phillips head screw Photo 5 I made no other modifications to the enclosure The DC voltage input con x nection was retained along with the two AC outputs and input fuse I changed the fuses value to 5A Note To preclude shocks do not con nect the output transformer until after making the initial measurements to ver PHOTO 3 Testing and initial electrical set ting of DIY AC synchronous motor controller with VPI motor attached to transformer ify the proper sinewave signal is applied to the input of U4 power amplifier into the exterior surface perpendicular to CIRCUIT MEASUREMENTS side the Inverter housing The TDA7396 Pin 2 of U1 oscillator output and pin 1 of U2 input MM74HC393 Dual Binary Counter had a measured AC voltage square wave signal of 2 48V AC at an operating frequency of 31 924kHz Pin 3 of U2 A output of first coun t
4. 9638 NW 153rd Terrace Alachua FL 32615 Tel 386 418 0560 wwwsilversonic com AC POWER SPEAKER INTERCONNECT amp DIGITAL INTERNAL Pure Silver amp Silver coated OFHC Copper HIGH CONDUCTIVITY COPPER CONNECTORS OMNIS mI SY S T E MI by dayton audio D A lt g F Eas E K lt s iy lt a ft K CA PTY 2 ks lt Tali ri K oy ai Dayton Audio s OmniMic is a must have for system integrators acoustic engineers and A V installers It was developed in collaboration with Liberty Audio inventors of the Praxis Measurement System The OmniMic provides quick and accurate measurements that will reduce installation time saving you both labor and money Test ae s U s signals may be initiated from ea usa a Qos the host computer or from any Mow raed A audio CD player System includes Measurements erat Pier i y h SPL meter with A B C or no weighting p j uu op alae Spectrum analyzer FFT or RTA mic clip software and test signal Frequency response with phase and impulse response discs 6 ft USB cable and Oscilloscope function to view complex waveforms carrying case Compatible e Harmonic distortion 2nd 3rd 4th 5th harmonics plus THD s e RT60 reverberation measures sound reflections with k a XP Vista e Bass decay function identifies room modes and helps and Windows 7 determine proper subwoofer placement Distributed By y Pa 725 Pleas
5. Bill Fitzmaurice Oct p 36 Ground Loop Basics By Example aX Digital Nov Editorials Champagne Fidelity Jan Didden aX Digital June Why Should You Change Your Sub to Digital Ed Dell June p 26 How Are We Doing Ed Dell Dec p 6 Loudspeakers Laminated MDF Three Way Speaker System Anastasios Fiakas Feb p 6 The 69 Line Ken Bird March p 6 Synthesized Bass Bohdan Raczynski March p 20 Stuffing And Sound Speed Cornelius Morton April p 12 Tang Band Full Range System G R Koonce May p 4 A Three Way Tri Amp Center Channel System Andreas Schilloff June p 5 A Loudspeaker That Can Play Square Waves Bohdan Raczynski June p 11 The Fire Stick Speakers Ken Bird July p 10 A Continuous Time Active Filter Ramkumar Ramaswamy Aug p 14 A Tang Band 3 System G R Koonce Aug p 23 The Mustang Speaker Claude Goeuriot Sept p 6 Low Frequency Horn Speaker Rich Johnson Sept p 18 The Low Profile Tuba Bill Fitzmaurice Sept p 28 A Subwoofer for the Reflection George Danavaras Sept p 36 E14 audioXpress 12 10 www audioXpress com Measurements OPPO BDP 83 Blu Ray Disc Player measured by Chuck Hansen aX Digital Sept Miscellaneous Power Supply Spreadsheet Paul Stamler aX Digital March Making Better Circuit Cards Ed Simon aX Digital April
6. to 0 9 disc and using the pencil carefully place 0 625 is too small Just put the bear ing and ball in a vise and slowly squeeze ter into the bearing so the ball nub on the bottom of the shaft seats in the dent the nub on the bottom of the spindle isn t in diameter An inch is too big and 5 8 You ll see a bright ring at the top of the sleeve where the babbitt is peened over Now comes the clever part Remove the inner platter and wrap two or three turns of Teflon thread sealer tape around the bottom of the shaft Replace the inner platter and its bearing shaft into _ the bearing well As you do the Teflon tape will deform evenly around the shaft shimming it to the center of the bearing i sleeve The nub at the bottom will settle into the dent centering it exactly Let this sit for a day or so to let the RTV cure completely To check your work remove the bits of Teflon tape _blacken the bottom of the steel shaft with a magic marker and spin it in the bearing a bit then remove it to check the bottom If you ve successfully cen _ tered the bearing disc the shaft will have turned free of the side walls and so be black all around shimmed to center it in the well using pliable tape First put a small dab of RTV x Keep at it bit by bit until the shaft just fits i e there s no clearance Now you need to open it back up sl
7. Subsequent to this warmup no de tectable frequency drift occurred and the output AC voltage change as mea sured at the power cord of the turntable motor was less than 1 5V I measured a DC input voltage at 15V DC at a cur rent of 1 2A Again I noted no chang es overnight in the input power supply voltage or current supplying the DIY x AC Synchronous Motor Controller Overall the unit performs very well and I ve had no problems with it Dur ing the overnight evaluation of the AC Synchronous Motor Controller the en closure heated up and it felt very warm to the touch It was not nearly as hot as the VPI motor which almost burns you if you keep playing the records without turning it off The VPI HW 19 Owner s ONE INCH may heat up between 30 C and 40 C 1 http pdfserv maxim ic com en an 2 http pdfserv maxim ic com en an AN21 pdf Ree amp FIGURE 3 PCB 2 silkscreen top side 3 http pdfserv maxim ic com en an 4 http cds linear com docs Datasheet 1799fbs pdf 5 http www fairchildsemi com ds MM MM74HC393 pdf 6 http datasheets maxim ic com en ds MAX7480 pdf 7 http www hurst motors com x documents PA_PB_Synch_DD pdf 8 http www amveco com pdf Amveco_ x Catalog pdf page 25 Accuracy Stability Repeatability Will your microphones be accurate tomorrow Next Week Next Year After baking them in the car AC
8. flopping over to the side I have great faith in RTV silicone as opposed to garden variety silicone adhesives I as sume it confers immortality on normally but they re worth mentioning Two motors 180 apart may help defeat any eccentricity that exists in the sub plat ter It also allows what I call a Mobius Twist to be introduced into the belt By this I mean on the side under ten sion counter clockwise from the pul ley give the belt a half twist Then move the other part of the half twist the untwist around the sub platter so it s on the tension side of the other motor his is said to help rumble Practically speaking you can use all those old belts that had stretched out so much that they barely stayed on the pulley Less belt wrap on the sub plat ter may mean less vibration conducted to the sub platter I also find the sym metry of the configuration appealing I would be remiss if I didn t give a tip of the modifiers cap to Mr Bill Fire baugh whose Well Tempered T table WTT began with screwing around with the AR XA When Audio pub lished a lengthy review of his design many years ago they detailed the tip of the twisted belt which being a single motor design entails a half twist on either side of the pulley instead of the Mobius Twist I use More interest ing the WIT deals with belt induced side load by making it into a virtue Mr Firebaugh used the belt to pull the top
9. Future Technological Workforce David Weinberg aX Digital July Music Reviews Super Fidelity by John Sunier aX Digital May Jazz Track by John Shand aX Digital June Super Fidelity by John Sunier aX Digital July Product Reviews Comparing Speakers Howard Ferstler Jan p 38 Swans M3 Speaker reviewed by Howard Ferstler Feb p 18 Dayton T1503A Subwoofer reviewed by Tom Nousaine Feb p 23 Personal Digital Recorders Part 1 reviewed by Keith Levkoff March p 10 DPA SMK 4060 Stereo Microphone Kit reviewed by Alvin Foster March p 24 PS Audio Power Plant Premier reviewed by Gary Galo aX Digital April Personal Digital Recorders Part 2 reviewed by Keith Levkoff April p 14 Lehmann Black Cube SE Phono Preamplifier reviewed by Tom Lyle April p 26 TDL Tuneable Stereo Rumble Filter reviewed by Don Walizer May p 27 THAT s Balanced Line Drivers and Receivers reviewed by Gary Galo aX Digital June Bryston BCD 1 CD Player reviewed by James T Frane June p 22 Emotiva XPA 2 Power Amplifier reviewed by Tom Lyle July p 24 OPPO BDP 83 Blu Ray Disc Player reviewed by Gary Galo aX Digital Aug Personal Digital Recorders Pt 3 reviewed by Keith Levkoff aX Digital Sept Jelco JL 45 Cueing Mechanism reviewed by Gary Galo Oct p 29 Infinity C336 Speaker reviewed by David Rich aX Digital Nov JBL LSR6325 Biamplified Studio Monitor reviewed by Tom Nousaine
10. PHOTO 3 Clip holding cables x ane PHOTO 4 Bottom view of inside components ings I always photograph each stage of staple and then finished with a pair of needle nose pliers After removing all the staples and screws I carefully pried the cover from the base taking care not to the process as a reference for use with the subsequent reassembly This has saved me no end of grief over the years and is a much easier process since the advent of digital cameras I then proceeded to photograph all stages of the disassembly turntable with RCA jacks I removed them so they would not be in the way during the CAPACITOR FIXES T0 125A www audioxXpress com 47nF This type of capacitor has spe _ cific properties that make it suitable for direct connection across the mains line You should always use capacitors that are certified for X2 across the line ap plications and bear UL CSA VDE and so on approval marks If not you may compromise safety with a possible fire if the capacitor should fail catastrophically The first upgrade involved replacing the potentially troublesome capacitor that _ was across the mains line In Fig 1 it i is identified as C52 and has a value of be working on the board I decided to also replace that one It is identified as C51 and has a value of 68nF Both ca pacitors are available from Digi Key www DigiKey com as part nu
11. The Optimized SRPP Amp Part 1 Merlin Blencowe May p 13 Amplifier Comparison Using Oscilloscope Waveform Plots Kent Smith May p 20 The Optimized SRPP Amp Part 2 Merlin Blencowe June p 18 Signal Current Loops amp Power Signal Interaction Richard Sears aX Digital Aug A 50W Pure Triode Power Amplifier Chi C Wong Aug p 18 A Push Pull 7591 Power Amp Karin Preeda Nov p 6 The Split Load Phase Inverter Revisited Cornelius Morton Nov p 20 Turntables A Power Sine Generator for Turntables Claude Goeuriot Nov p 10 Turntable Speed Control Joel Hatch Dec p 22 All About Stroboscopes Ron Tipton Dec p 18 A Dual 701 Turntable Tune Up Tom Perazella Dec p 8 Vertical Cut Blending Ron Tipton and Don Walizer Dec p 36 The Wretched Excess AR Turntable Renovation Pt 1 Tom Yeago Dec p 28 AUTHOR INDEX Bird Ken The 69 Line March p 6 The Fire Stick Speakers July p 10 Blencowe Merlin The Optimized SRPP Amp Part 1 May p 13 The Optimized SRPP Amp Part 2 June p 18 Brown Bruce 15 Watts per Channel for Less Than 150 Jan p 22 Charvat Gregory L Portable Tube Preamp March p 16 Crawford Dick The BTO July p 5 Danavaras George A Subwoofer for the Reflection Sept p 36 Danbury Mike Preamp Muting Circuit aX Digit
12. Top view of the DIBOND laminate motorboard just laid out everything on the film covering with a marker drilled and fitted peeled off the film and was ready to glue down leather ing little orbits within the tolerance of its components Plus you get more torque to OTHER COSMETICS For the motorboard I used an interest ing material called DIBOND Photo 6 _ which is a sandwich 4mm thick of two layers of aluminum each maybe 0 75mm x cope with the slightly heavier platter Everything else about the drive is stock ve thought about fiddling with variations on the 0 1uF cap 15 say to see whether the vibration drops down any Or u I might install a series resonant L C filter to keep out some of the grunge on the line If you try any of these methods let us know by writing to the magazine I also used small steel caps for the mo tors to help shield the cartridge from any with a peel off film on one side which I _ used to lay everything out I used flathead patch something together from the cases and with the DIBOND I just drilled the ed to rout out the new pieces to match stray magnetic field The days of steel caps for spray cans are long gone so I needed to of some old forlorn cassette deck motors T MOTORBOARD PLINTH thick around a pretty high density poly mer what kind I don t know Sign mak machine screws for the spring hangers FIGURE 2 Section
13. a protractor disk instructions and an oscilloscope I already had the oscilloscope and obtained the rest of the items from the Old Colony Catalog at www audioXpress com Their test LP from Hi Fi News part number the skating force is also not linear _ There are two scales one for conical styli and one for elliptical The owners manual states that one scale is white and one is red However on my unit one scale is black and the other is red I used the red scale that had a symbol for an elliptical stylus According to the manual you should set the anti skating level to the same number that you have _ for tracking force In my case my track _ ing force was 1 5 grams so that was the i setting I used in the anti skating dial LP2 produced by Len Gregory also includes the required protractor and in structions In addition as a comparison for the anti skating test I used the blank band 4 of the Shure Audio Obstacle Course TTR 101 LP The first step was to level the turn table and connect the audio leads to a standalone phono preamp that I built I x then fed the output of the preamp to the oscilloscope Next I checked the cartridge align ment in the head shell with the protrac tor The cartridge had originally been mounted using the gauge supplied by Dual You mount the cartridge so that the stylus tip is centered in a V shaped cutout in that gauge
14. box away from the side of the board that is in the slot and lifted the board out Next I turned the board over and re moved the two capacitors The 68nF x capacitor is the same size as the original and you can simply solder it into place The 47nF capacitor has a lead spacing that is less than the original Instead of bending the leads at a sharp angle to fit wez die ae l k za ak V ae PHOTO 7 Connections on mercat board I the existing spacing I decided to drill two new holes centered between the old ones I inserted the capacitor into the new holes and used hook up wire to connect the leads to the old pads as shown in Photo 7 The board with the new capacitors is shown in Photo 8 I x then reinstalled the board reconnected the leads and replaced the cover through the box and the other end fits LUBRICATION It always amazed me that the Dual turntables seemed to be able to do the same functions as their British coun terparts using about half the number of components However even the fewer parts in this design occasionally need _ lubrication I was actually quite surprised that the turntable worked for as long as it had with my neglect of lubrication x The service manual was quite helpful x THE WINGS OF MUSIC The Airborne line of drivers was developed to fill the gaps left by the industry in the use of exotic and unconventi
15. especially the Samsung Gal http GalaxyS SamsungMobile com Heiss called it a very good An axy droid based tablet Crestron offers an iPad sleeve that adds hard buttons to complement the iPad s soft buttons The Radio Frequency for Consumer Electronics RF4CE consortium has merged with the ZigBee Alliance www ZigBee org to push for inclusion of RF remote control in consumer electron ics devices to make multi room and hidden systems easier to control from afar They pointed to wireless and net work Internet connectivity as critical to new and retrofit installations Nuage Nine www NuageNine com has partnered with Crestron www Crestron com to offer remote moni toring and error prediction discovery for home systems A competitor is ihi jis pronounced eye he gee www ihiji com invision which is a cloud based remote monitoring solution With respect to distribution net working and connectivity not ev erything can be accessed from the cloud Because of the complexity of home networks A V systems and the desire for wireless integrators should seriously consider enterprise grade wireless network solutions over consumer grade models Powerline networking such as products from Russound www Russound com and Nuvo Technologies www Nuvolech nologies com and MoCA Multimedia over Coax Alliance www MoCAAI liance org offer other ways to network a home with minimal additional wiring E2 audi
16. who decide about advertising in our pages and those of you who are sending your renewals We are all asking each other How are you doing or Hope all is well with you It is a hard time and one which often appears endless I think we are all tempted in our frustration to look for scapegoats or people to be mad at for causing all this We would do well to step back and give some calm thought unaffected by our feelings about where we are and why My answer to people who inquire about the situation at Audio Amateur is to reply that we are responding in positive actions Some of our people are work ing off site and in a case or two fewer hours We have been cutting costs in a number of ways We are using less paper we use heating oil more sparingly We work four days a week We have been using interns occasionally We are encouraging readers to seriously consid er digital versions and delivery of all our periodicals This is working and we are seeing lower printing bills every month AudioXpress is now being distributed on newsstands in Europe and Britain Our office has been helped enormously by a local IT company and the addi tion of Google s wonderful apps Docs g mail and calendar This links all of us together as editors customer servants marketing and advertising We are in sofar as possible using open source soft ware believing that such widely used capabilities should not be monetized indefinit
17. 14 It took less than a quarter i turn of the screw to achieve proper op eration Using more than that resulted in that links the automatic start and stop lever on the top of the platform to the actuating mechanism is shown in Photo excessive force on the arm which caused The levers that control the manual lift and 17 They needed to be cleaned and lubricated Photo 17 also shows the link ages for the anti skating section The lever 18 As with the others I cleaned then lubricated them I then reassembled the actuating cam and tested the operation of the mechanism At this point the opera AUDIO TRANSFORMERS AMERICA S PREMIER COIL WINDER Engineering e Rewinding e Prototypes McINTOSH MARANTZ HARMAN KARDON WESTERN ELECTRIC TRIAD ACROSOUND FISHER CHICAGO STANCOR DYNACO LANGEVIN PEERLESS FENDER MARSHALL ELECTROSTATIC TRANSFORMERS FAIRCHILD 660 670 RCA LIMITERS WE DESIGN AND BUILD TRANSFORMERS FOR ANY POWER AMPLIFIER TUBE PHONE 414 774 6625 AUDIO TRANSFORMERS 185 NORTH 85th STREET WAUWATOSA WI FAX 414 774 4425 53226 4601 E mail AUTRAN AOL com NO CATALOG CUSTOM WORK audioXpress December 2010 13 PHOTO 14 Tonearm actuator assembly tions under the deck were complete The remaining parts to be lubricated were the hinge assemblies that operate the dust cover To remove them from the base first release the spring tension by x using the knur
18. 5 Record noise hypothesis www audioXpress com 10000 20000 VERTICAL CUT GROOVE ing force of the stylus on the groove wall which is pro portional to the sine of the angle of the groove walls as measured from the vertical centerline of the groove On the other hand a ver tical cut record has a nearly rectangular groove because all of the signal is in the groove bottom A small relief angle is necessary so both the freely in the groove If the output noise is proportional to the sine of the groove wall angle then a vertical cut recording will have less groove wall noise Of course the bottom of the groove can still be noisy but this would be present in both the left and right out puts so blending would not be helpful The authors welcome questions and comments ei ther directly or through Let ters to the Editor You can contact Don at ecg conway corp net and Ron at RTip ton tdl tech com aX REFERENCES 1 You can find the Model 4010 datasheet and user guide at http www tdl tech com data4010 htm See also Product Review The Restoration Preamp aX 4 09 p 36 2 The graphs in Figs 1 4 were made using the TrueRTA Real Time Audio Spectrum Analyzer software from True Audio 387 Duncan Lane Andersonville TN 37705 http www trueaudio com 3 The Headshell graphics Mag _cartridge png in Fig 5 was borrowed from the Wikipedia web page on Stereo Pickup Cartridges Oatl
19. April 10 issue CEDIA published a 2010 Electronic Sys tems Contractors Licensing and Regulato ry Reference Directory which delineates by US state and Canadian province the licenses needed to legally perform cus tom installation work and licensing or ganizations that issue them There was no new hardware or soft ware that stood out from the crowd Display marketing focused on 3D At least one manufacturer had universal 3D glasses but would not lend them for a floor tour to see how universal they were Naturally 3D panels and projectors were widely displayed However there are four mutually exclusive 3D display technologies under development three of which require each viewer to wear glasses that only work with one of them Psychovisual focus distance conflicts cause headaches and nausea in some viewers which 3D movie creators will need to learn to avoid Many consumers have recently bought new high defini tion displays Blu ray players and HDMI cables and they likely will be reluctant to replace those so soon and at higher cost than their previous purchases Thus 3D is an unsettled landscape that needs domesticating and stan dardization before the risk of planting the soon to be rejected technological seed in your home is low enough to warrant the expense Embedded com puters have become commonplace as has consumer acceptance of networks wireless audio and video and so on PRESENTATIONS AND COURSES Th
20. I DEPARTMENTS EDITORIAL XPRESS MAIL CLASSIFIEDS AD INDEX BONUS ARTICLES FOR DIGITAL SUBSCRIBERS To become an aX digital subscriber send your name and e mail address to Sharon at custserv audioXpress com WEBSITES YOU SHOULD KNOW www audioamateurinc com Www audioxpress com www voicecoilmagazine com www audioxpress com or call 1 888 924 9465 to order 4 amateur incorporated LEGAL NOTICE Each design published in audioXpress is the intellectual property of its author and is offered to readers for their personal use only Any commercial use of such ideas or designs without prior written permission is an infringement of the copyright protection of the work of each contributing author audioXpress 12 10 SUBSCRIPTION CUSTOMER SERVICE INQUIRIES A one year subscription to the printed edition is 50 for 12 issues Canada please add 12 per year Overseas rate is 85 00 for one year A one year subscription to the digital edition is 25 for 12 issues worldwide All subscriptions begin with the current issue To subscribe renew or change address write to the Customer Service Department PO Box 876 Peterborough NH 03458 0876 or telephone toll free US Canada only 888 924 9465 or 603 924 9464 or FAX 603 924 9467 E mail is required for the digital edition E mail custserv audioXpress com Or online at www audioXpress com www multimediamanufacturer com For gift subscriptions please include gift recipient s name and
21. When I checked it with the protractor it was right on No _ ward the center of the record To get the i arm to remain stationary on the blank contains identical 300Hz tones in both the left and right channels that are out of 2 phase You can test this without instru the bias bands of the Hi Fi News test LP Bands 6 9 on the front side each contain a 300Hz tone but recorded at four dif a sum function on my oscilloscope that ef ferent levels of 12dB 14dB 16dB and 18dB respectively A simple test _ requires that you listen to the tones from each channel and identify any distortion You can then adjust the anti skating force to minimize the distortion For a more critical test you can direct the left and right cartridge outputs to two differ adjustment was needed but it was good to have confirmation of a correct setup With a pivoted tonearm distortion x ing force of 2 5 on the dial PHOTO 23 Operating view of strobe 16 audioXpress 12 10 i PHOTO 22 New neon in housing will occur due to a vector force that tries to move the stylus in toward the center of the record This is commonly called skating The Dual 701 like most turn tables has the ability to apply a force to help offset this skating force On the 701 it operates in a nonlinear manner as the arm moves across the record because reached At that level the distortion
22. acronym standing for Yet Another Hybrid Amp A German friend of mine has built one and says Although the circuit is all wrong from an engineering per spective It sounds good Moreover a tube microphone from Audio Technica www audio technica com with a 600 price tag Photo 1 employs a single 6814 as the ac tive element Thus thought that the K272A was worth trying The proof of the amplifier is the listening CONSTRUCTION The K272A is packed in a plastic bag con taining a printed circuit board PCB all elec tronic parts and a construction manual The PCB looks gorgeous It is plated through dual layered solder masked and screenprinted Very nice The parts supplied correspond exactly to the bill of materials in the manual Even rubber grommets are provided though the manual specifies that these are optional and should be bought separately The active devices are from well known manufacturers two Raytheon 6418 valves in date stamped original boxes an L4949 IC from SGS Thomson a PT2308 from Princeton Technology Corporation and a C8050 transis tor from India Compared to the PCB and ac tive devices the passive components were a slight disappointment My bag contained quite ordinary generic parts carbon film resistors radial electrolytics and foil capacitors How ever the values of all resistors deviated less than 2 and those of all capacitors both foil and electrolytic less than 10 from
23. and many other sources He cautioned that many of the adjustments interact so it re quires an iterative process to get the best image from a display Silver said that the gamma the curve of each color s transition from black to white is quite variable even among the pixels of a display making it difficult if not impossible to get a uniform gray field over the whole screen LCD tech nology typically displays an S shaped gamma that should be but is not always corrected by the display s manufacturer because such correction tends to reduce the screen s maximum light output HOME THEATER Floyd Toole repeated his three part se ries Home Theater Audio and Acoustics with much of the content also in his book Sound Reproduction The Acoustics and Psychoacoustics of Loud speakers in Rooms 47 at www Amazon com Part one started with a review of the physical and perceptual aspects of sound waves in air speed wave length and frequency followed by the complications added by the room and room treatments resonances reflec tions speaker directivity and so forth Graphs accompanied his explanation that because wavelengths get shorter as frequency increases a driver woofer midrange or tweeter becomes more di www audioXpress com rectional toward the top of its frequency range Starting with the assumption that the loudspeaker was designed for the flattest on axis frequency response this causes the lo
24. balanced interface is one in which each conductor is equal in voltage but opposite in polarity to the other is absolutely incorrect He ex plained that the resistor tolerances in line drivers seriously degrade the po tential common mode rejection ratio CMRR for example the CMRR of the widely used Analog Devices SSM 2141 will degrade some 25dB with only a 192 imbalance which can happen us ing even 1 tolerance resistors He also discussed the XLR pin 1 problem s causes and methods of prevention In discussing RFI Whitlock explained the appropriate use of ferrite clam shell cores which provide little help below about 20MHz Also covered was a Straightforward procedure for stepping back through an equipment chain to find the source of noise seen or heard at the system s output He talked about power isolation filters and balanced power explain ing that in his experience treatments to cleanse or purify the AC power feed offer marginal improvement and that even balanced power proponents ad mit that actual noise reduction is usually under 10dB and rarely exceeds 15dB Whitlock is a proponent of series power line noise suppression such as in products by Surge X Photo 3 www SurgeEx com With parallel power line suppression devices which typical ly are MOVs between the hot neutral and ground lines during a power line surge or spike very high current will be induced in
25. by hand put a stethoscope to the bearing and heard nothing The final touch was cutting a couple discs of roofing paper and gluing them to the top using DAP to bring the top surface of the inner platter level with the outer platter And for what it s worth I use a rubber mat from some forgettable Japanese table It weighs about 200gm so it brings the total weight to about 2 4kg 5 3 lb which compares to the x 1 5kg 3 3 Ib stock unit PREPARING AND HANGING THE SUB CHASSIS I ve read about others who have worked around with the XA sub chassis see the work of Galo in Audio Amateur x Press The LP Is Back www audioxpress something eventually occurred to me Nobody seemed to be paying attention each spring saw the same mass I rea soned each would bounce at the same frequency so there would be no ten dency for rocking that is the arm end and platter end would tend to bounce in unison in synch For you modifiers who have had trouble dressing relatively heavy tonearm cabling this analysis would sug gest dressing the cable so its attachment point on the sub chassis is there at the center of gravity again the point being to present the same load both resistive x filled up the inner platter with a mix of x clean sand and DAP Alex Plus caulk and sealed it off with a disc of 4 thick concrete backer board what you screw and reactive to each spring For th
26. clock position lower line This is a _ very audible effect and is also quite vis ible Fig 3 The lower line is the center position response Figure 4 shows this comparison using the Ortofon cartridge The maximum null occurred at the cen ter position lower line The one o clock spectrum is the upper line Again these results are both audible and visible I repeated these tests with several Edi 10000 20000 Frequency Hz FIGURE 2 Comparison of LR blend control full left with full right Ortofon cartridge with utility amp This figure shows nearly perfect channel balance 10000 20000 Frequency Hz FIGURE 3 Comparison of LR blend at the center position lower line with the one o clock position Stanton cartridge with turntable connected directly to 4010 inputs This figure shows the Stanton cartridge channel imbalance Ready willing and offering an extensive range of ready to go toroidal transformers to please the ear but won t take you for a ride G Avel Lindberg Inc 47 South End Plaza New Milford CT 06776 tel 860 355 4711 fax 860 354 8597 sales avellindberg com www avellindberg com State of the art engineering Extreme reliability Joyful sound Auricaps are precision wound If and are considered by many to be the finest capacitors available Stereophile June 06 Peter Breuninger QU o O simply the highest resolution and most cohere
27. decided to check my records and x found that in 1975 I was in the process of drooling over the reviews of this spec tacular new turntable That eventually led to my purchasing one that summer I still had the original product sheet a re view from the spring 1974 HI FI Stereo of excellent listening in the ensuing 30 years of use and proved to be an amaz ing value I did not hesitate to begin the tune up process DISASSEMBLY Before starting the project I searched PHOTO 1 Hinges on back of case 8 audioXpress 12 10 Bual 701 T550 110 125V 0 1 amp lt i Dual Gebr der Steldinger ee ee Made i the web for other problems that may have been common with the turnta ble but I had not yet encountered A great resource is www vinylengine com I found that there were a reasonable tonearm and put it aside in a safe place to prevent damage to my irreplaceable number of failures of a suppression ca tion while working The inside dimen sions of that stand were 1314 x 15 13 16 In preparation for the tune up I re moved the clear plastic dust cover by moving it to the open position and then lifting it out of the two spring loaded hinge clips located at the rear that hold it in place One of the hinges is shown i in Photo 1 Next I secured the turntable to the www audioxXpress com base using the built in shipping screws x and also secured the tonearm to its res
28. dk http www partsconnexion comi t Index burson_reg html Team Burson spent many months developing the Burson Clock The clock is made from the best materials Eina Capacitors extra thick gold plated pcb Without a Doubt the Best Aftermarket Regulator Available DALE military graded resistors Also each of the clocks are carefully assembled and tested Before shipment each clock i fine tuned to ensure it is producing the most ideal square Burson Series 2 Super Regulators are a direct replacement for some of the most wave for the bes performance commonly used TO 220 style 3 pin fixed C based regulators and are based on Burson s advanced PS design technology The performance of this master oscillator ensures much improved jitter specifications which is what translates into improved sonic performance As a result the listener can These vastly superior shunt type regulators constructed with 17 discrete audiophile expect greatly enhanced boss dynamics ambience and soundstaging grade components each also incorporate a noise filtration network which further enhances performance by screening out unwanted upstream PS noise To see the Burson Digital Clocks http www partsconnexion com t index burson_clock html Now with stable noise free and low impedance power the listener will hear bass with more control a more 3 dimensional soundstage with a greatly improved low level detail retrieval PARTS CONNEX Th
29. left eye image above a 1920 x 540 right eye image thus reducing the vertical resolution by half Satellite and cable systems will distribute 3D in the side by side frame format A trade off for home 3D viewing is between conventional panel displays with adequate frame refresh rates 3D processing and active shutter 3D glasses and polarized panel displays which are more expensive to manu facture but use less costly 3D glasses One size of 3D glasses does not fit all people especially kids versus adults Plus none of the 3D glasses are easily worn by people who wear glasses Another problem is that the 3D glasses from one display manufacturer might not work with another manu facturer s display even using the same 3D glasses technology For example one informal test showed that Pana sonic 3D glasses worked with a Sam sung display but Samsung s 3D glasses did not work with Panasonic displays The cost of active shutter 3D glasses is quite high especially considering that you need a pair for each person in your audience Two of the universal 3D glasses are XpanD Photo l www XpanDCine ma com an IR based system 130 on www Amazon com and Monster Ca ble s www MonsterCable com Mon ster Vision Max Photo 2 3D glasses an RF based system 250srp for one pair with transmitter 15Osrp for ad ditional glasses A problem with IR based 3D glasses is that high ambient light can cause them to malfunctio
30. neon night light makes a usable but dim stroboscope lamp are available For my use I built a multiple LED and the wiring is not at all critical much clearer than with an incandes LED Array Stroboscope Lamp PHOTO 7B Inside view of the multiple LED lamp The male power connector mates with the connector from the 12V AC wall transformer The power on off switch is op tional because you can unplug the lamp from the transformer www audioxXpress com 12 VAC wall transformer Part of the AC wall transformer 2 1 of 2 5 mm power connector depends on P1 Mouser Kobiconn 163 4302 E or 163 4303 E SPST toggle switch optional 165 ohms 2W or higher Schottkey diode 1N5819 14 white LED array 12 V such as Marlin P Jones type 17356 OP see note 7 Enclosure PacTec model CM3 100 see note 8 different enough that individual current limiting resistors must be selected for each lamp This makes construction a _ field NJ 07062 908 754 1479 www kabusa com chore so I decided to settle for the mul tiple LED lamp which works very well SOME FINAL THOUGHTS A stroboscope is useful if for no other reason than periodically checking your x 2 Square New Hope PA 18938 800 724 8333 www ultrasystems com turntable speed Many modern turnta bles have strobe bumps cast or molded into the platter rim Photo 8 which are x useful for 33 1 3 and 45 RPM records These may suffice i
31. of the bearing shaft against two plastic pads and likewise with the bottom of the shaft except the bottom pads are on the opposite side of the bearing well voila zero clearance bearings Finally eagle eyed readers may won der at the motor mounting hardware I used It looks suspicious but isn t I just tapped some aluminum bits I had on hand and used them for nuts There is a rubber piece between these odd nuts and the motorboard but I hardly think the rubber functional The motor chas sis is held fast to the aluminum face of the bottom side of the board so there s no vibration isolation involved There s less here than meets the eye Im MORE SUB CHASSIS PREP So much for the theory and the damp T bar you see in Photos 3 and 5 I glued this on using DAP again to add mass and prevent ringing The hangers on in American Phillips Co with their re i spective pulleys both filled with a mix of DAP and lead sand to add a slight flywheel effect They re mounted 180 apart at approximately 12 30 and 6 30 if you take the platter as a clock face This also puts them at the greatest distance from the arc the cartridge traces and clude fiberglass PCB material chunks of concrete backer board on the bottom and hanging on the bottom of the bear ing wells some lead alloy flywheels ac cumulated from decrepit tuners over the years I figure added mass right there at the sources of
32. oscillator frequen cy as follows Repp 1 x 1011 N FOSC 2 2 Ropy versus Desired Output Frequen cy N was selected for a factor of 100 From the graph I then substituted the values for these variables to give a de sired oscillator setpoint resistor of Rspr 1 x 1011 Hz 100 15 360Hz 65 104kQ 3 MM74HC393 datasheet is found at reference 5 while the MAX7480 data mouser com and found a few fairly close resistor values From my proto type experiments I wanted to have a I consulted my Mouser catalog www minimum of 2Hz adjustment in either direction from 60Hz For this reason I selected a standard resistor value slightly less than this 61 9kQ with 1 tolerance I then selected a standard 5kQ value lower THD operating curve see Fig 11 and Table A of MAX7480 datasheet fine frequency adjustments of 2Hz The MAX7480 output is a sine wave 5 10 turn potentiometer to provide Calculations indicate a frequency span A Dynamic Petronmance AW w ga W Wiwaku W Wik A An V When an orchestra a rock band or a Jazz ensemble delivers with every emotion it s a dynamic performance To play with full emotion your electronics needs rock solid power sources delivering pure quiet DC of approximately 58Hz to 63Hz You vides a filter corner frequency meeting ment span and tolerance by using a 64 9kQ resistor and 1kQ potentiometer Note Measure the setpoint resisto
33. potential noise the bear ings will help dissipate that noise For the whole before after story go to Table 1 I should add that I accounted for the weight of an LP pegged at 120gm and a record weight I use steel from some loudspeaker motors I dissected for the magnets about 220gm Given the above maybe it s worth in cluding a word or two about tolerances An LP weighs anywhere from just less than 100gm to 180gm for the high dol lar reissues which introduces a 40gm variation centered 62mm from the center of gravity This variation is less than 1 of 5 1kg so I m not losing any sleep over this In terms of deflection if that 40gm were plopped down on the centerline be tween the two platter end springs you re looking at half a millimeter difference in om u s k I T ki t Ay 4 x i Sei k WY i a Pere G r a ANA y a 3 K Kar S s tines deflection which I can also live with but that s worse case than the reality ers What about the other objects on the THE DRIVE SYSTEM I use two stock AR synchronous mo tors made by A W Haydon Co a N clears the sub chassis The point of two motor one belt drive is that it avoids adding lateral force to the _ platter This lets the bearing settle in and spin concentrically as opposed to mak TABLE 1 COMPARATIVE MASS OF VARIOUS
34. precau tions necessary for working around high voltages This circuit is capable of output x ting hundreds of mA at up to 200V AC As noted I connected the U4 power x amplifier s output terminals via W3 and W4 to the output toroid transformer These outputs are not connected to ground Transformer T1 s 120V AC windings are connected to the output x connectors W5 and W6 Caution Note that W6 is connected to circuit ground The AC Synchronous Motor Controllers 120V AC output is only two wire Follow applicable safety precautions for operating a two wire AC circuit As noted in Radio Shack s operating instructions for the DC AC inverter the ground prong of the three prong AC receptacle is not connected To ensure safety I connected a GFIC ground fault interrupt circuit cord to my turntable motor You can readily ac quire these at the local thrift shop for a couple of bucks I bought a hair dryer and clipped the cord off connecting it to the turntable s motor Final output voltages from U4 x TDA7396 power amp to transform er were measured at 4 35V AC pin 5 and 4 27V AC pin 7 at a frequency of 60 05Hz With the turntable motor connected as a load I measured the input voltage to U4 TDA7396 power amp pin 1 at 0 43V AC for an output of approximately 100V AC at the motor Subsequent to making the final out put measurements and adjusting the ou
35. processor and tweak the setup then use the primary source such as a Blu ray player and test disc for final adjustment He spoke about room lighting the need to keep room light off the screen the need for a little light in an otherwise totally dark room if the display is espe cially bright the fact that colors other than neutral gray within the viewers sight will shift their perception of col ors on the screen He pointed out that PHOTO 2 3D glasses from Monster Vision audioXpress December 2010 E5 a separate calibration setup is required for dark room and for daylight viewing because most people have their display in a multipurpose room Silver and others worked with Spec traCal www SpectraCal com in the development of the highly regarded CalMAN video calibration software that works with a wide variety of color sen sors and PCs it does not run on Mac OS X SpectraCal sells the software alone or in packages with various hardware and will do their best to help it work with your existing hardware A free eval uation copy is available for download There are various licenses roughly 200 2000 depending on the license and included functions for specific pricing request a quote Terry Paulin used CalMAN for his projector reviews in the July August September 2010 Widescreen Review and the data pre sentations as well as the reviews were the best recall in a home theater mag azine Video gurus Charles
36. the bot tom through 3 8 dowels into the wood Photo 7 This presses the motorboard and its cover tight against the wooden lip Fig 2 Because the structure is al most square I use the same size dowels with the same screw spacing all around I used leather to cover the motor board This glues up well with spray upholstery adhesive peel the protective film off the DIBOND first and is flex ible enough that you can turn it over the edges of the holes for the platter spindle and arm It looks rich and isn t too ex pensive if you buy a remnant from an x upholstery shop So much for the table Next month in x the digital edition of aX I ll address the tonearm which I call the Defarge arm aX Electronic and Electro mechanical Devices Parts and Supplies Many unique items www allelectronics com Free 96 page catalog 1 800 826 5432 ADVERTISER ACO Pacific Inc Antique Radio Classified Audience Audio Advancements LLC Audio Transformers Avel Lindberg Belleson Consumer Electronics Association CES DH Labs Audio Cables Electra Print Audio Co 33 Front Panel Express LLC Goldpoint Level Controls Hammond Manufacturing Jantzen Audio Denmark KAB Electro Acoustics Linear Audio Madisound Loudspeakers VENDORS x AudioClassics com Buys Sells Trades Repairs Appraises McIntosh amp other High u End and Vintage Audio Equ
37. the final instal lation step is always done by owners who press the install confirm button in the privacy of their own homes was waiting and watching to see what the music and movie companies would say about this But events have overtaken the issue Imerge has now closed down There was no official announcement but an insider tells me Imerge is owned by a US group called Nortek Nortek filed for Chap ter 22 towards the end of last year and a couple of months ago announced a restructuring downsizing program that involved separating itself from the businesses it owns outside of the US that of course includes Imerge which has been based in Cambridge since the company s formation in the 1990s For the past couple of months Imerge has been attempting to negoti ate a management buyout MBO with financial backing from a Saudi group All concerned fully expected the deal to go through negotiations were at an advanced stage and we were sim ply waiting to hear that the deal had been sealed However out of the blue Nortek decided to pull the plug on ne gotiations and instead enter into an or derly wind down of Imerge Right up until a few days ago Cam eron Wade Imerge s CEO was work ing very hard trying to resurrect a deal but it was not to be will never understand why Nortek decided to pull out of negotiations at the last minute A strong offer was made and all indications were that
38. the safety ground wire substantially raising the ground volt age at the equipment leading to high ground voltage differences between in terconnected equipment plugged into different outlets and potentially caus ing equipment damage White papers and additional information on these and related topics are available on the Jensen Transformers website www Jensen Transformers com VIDEO AUDIO AND SYSTEM CONTROL The CEDIA Technology Council and Harman sponsored the Future Tech nology Pavilion which was to show case and highlight emerging trends and cutting edge technologies in the home from the bedroom to the garage from the CEDIA show directory In addition to home theater the pavilion included areas devoted to home health monitor ing care and energy management The future of displays was repre sented by NanoLumens s www NanoLumens com 112 diagonal 8 wide flexible display LEDs on polymer substrate lt 1 thick 80lbs 75 000 that can be wrapped around poles or otherwise rolled up Photo 4 The company can manufacture these displays in a wide variety of sizes with different pixel pitches the 416 x 224 pixel display in the pavilion had a 6mm pixel pitch pitches can range over 4 10mm in a 16 9 aspect ratio pixel counts depend on pixel pitch and screen size It was designed for view ing from at least 15 This display was adjusted for a maximum white level of 500nits 146ftL but can d
39. was The first anti skating test I did was to use the recommended force and then too low and caused the arm to skate to section required an indicated anti skat In the second anti skating test I used www audioxXpress com ent traces of an oscilloscope and look for waveform distortion on either channel at the different levels of modulation I proceeded with the oscilloscope test During the test it was interesting to note that at the setting suggested by the blank band test there was no vis ible distortion until the 18dB level was only in one channel and increasing the anti skating force further to a scale set ting of 2 75 eliminated it It appears that manufacturer recom mendations may be considerably off from what is truly needed Using the x blank band test is a better method of set ting the force but actually looking at the reproduced waveforms is the best way to set this parameter The large discrepancy in the setting recommended by the man ufacturer could be the result of decreas ing spring tension of the mechanism with old age yielding a force that is actu set the tonearm down on to the blank section of the Shure Audio Obstacle Course record That level proved to be stylus is not perpendicular to the record ally less than that indicated on the dial Band five of side 2 of the Hi Fi LP contains a cartridge alignment test If the surface the outputs of the right and left channe
40. when the filter is used and that the total energy _ is displaced into two smaller outputs at two frequencies You can t get rid of the energy but you can disperse it so that the effect is less intrusive on the signal Figure 3 shows how the system damps resonances by showing outputs for the both filtered and unfiltered arms being dropped on a grooveless record The filter has a profound effect on the amplitude of the signal generated The measured resonance of the arm with my Ultra 500 mounted was 8Hz I have always had excellent bass re sponse with this combination and no problems even with severely warped rec ords The Ultra 500 also has a built in damper in the form of a small pivoting brush attached to the cartridge body that will damp vertical and horizontal movements but I did not use it for this test The resulting resonant frequency is strictly the result of the interaction of the tonearm and cartridge warps and off center holes with cartridges With most tonearms that are rigid from The turntable is now happily back x In my system and I expect many more designed to accommodate compliances of from 15 to 50 x 10 cm dyne x compromise that provides acceptable bass performance without making the arm too years of superb performance If you have an old turntable that is getting a little rickety consider taking the time to give ita tune up Patience and att
41. your own with remittance A gift card will be sent EDITORIAL INQUIRIES Send editorial correspondence and manuscripts to audioXpress Editorial Dept PO Box 876 Peterborough NH 03458 0876 E mail editorial audioXpress com No responsibility is assumed for unsolicited manu scripts Include a self addressed envelope with return postage The staff will not answer technical queries by telephone www audioxXpress com audio ress THE STAFF Editor and Publisher Edward T Dell Jr Vice President Karen Hebert Assistant Publisher Editorial Assistant Graphics Director Marketing Director Customer Service Shipping Manager Dennis Brisson Richard Surrette Jason Hanaford Laurel Humphrey Sharon LeClair Mike Biron Regular Contributors Chuck Hansen G R Koonce Tom Lyle Erno Borbely Richard Campbell Dennis Colin Joseph D Appolito Vance Dickason Jan Didden Bill Fitzmaurice James Moriyasu Nelson Pass Richard Pierce David A Rich James T Frane Paul Stamler Gary Galo Advertising Department Strategic Media Marketing 1187 Washington St Gloucester MA 01930 Peter Wostrel Phone 978 281 7708 Fax 978 281 7706 E mail peter smmarketing us Janet Hensel Advertising Account Coordinator audioXpress US ISSN 1548 6028 is published monthly at 50 00 per year Canada add 12 per year overseas rates 85 00 per year by Audio Amateur Inc Edward T Dell Jr President at 305 Union St PO Box 876 Peterbo
42. 6 Tritschler Joe Borbely RIAA with Tubes Revisited Jan p 27 van Waarde Aren The Modern Homodyne Oct p 16 Review Oatley Electronics K272A Headphone Amp Dec p 39 Walizer Don Review TDL Tuneable Stereo Rumble Filter May p 27 Vertical Cut Blending with Ron Tipton Dec p 36 Weinberg David Future Technological Workforce aX Digital July CES 2010 Changes Abound aX Digital Aug CEDIA 2010 aX Digital Dec Wong Chi C A 50W Pure Triode Power Amplifier Aug p 18 Yeago Tom The Wretched Excess AR Turntable Renovation Pt 1 Dec p 28 E18 audioXpress 12 10 www audioXpress com The design and manufacturing quality of the audio cables you use can go along way towards determining the success of your project Select audio cables where the genetic code is clear SILVER SONIC cables designed by DH Labs and made in the USA Utilizing a synergistic combination of silver and oxygen free copper conductors SILVER SONIC cables are the most transparent way of carrying musical signals between audio components Buy it by the foot by the spool or terminated with our own high conductivity copper connectors Dont settle for cable mutations of questionable lineage Insist on SILVER SONIC cables for all your work think of it as genetic engineering for audio Visit our website for more information or to find a dealer near you
43. Blu ray s allegedly un hackable protection that appealed to the software industry after DVD s allegedly un hackable CSS was hacked by a schoolkid As we in Europe saw when Nelson Riddle s clas sic score for the 1966 Batman movie was released as an audio only extra on a Blu ray disc only in the US re gional coding for video can tie up audio content as well Imerge www imerge co uk pretty much invented the hard drive music store product category We developed the first audio server in the 1990s and lost our way in 2006 7 But we now have a new team and have now sold over 25 000 servers said CEO Cameron Wade earlier this year when Imerge launched its new servers and XiVa online music store in partnership with Digital Owners of Imerge server boxes use a computer to access a web page sign up for the XiVa download service and enter credit card details They can then use the server s remote control to make click purchases from over 8 million mu sic titles Virtually all recorded music is offered with only a few notable excep tions such as Beatles tracks and AC DC because of industry holdouts Pric es range from between 70 and 90p per track and from 5 to 11 per album There is no DRM digital rights management Once purchased and downloaded to the server music can be copied freely to other devices Us ers can also download the same tracks three times The hard disc uses an auto backup system call
44. December 2010 US 7 00 Canada 10 00 PRE A TUNE UP FORTHE Tube Solid State Loudspeaker Technology Rq lt r DUAL TURNTABLE BR ar A PIIN SONNET E gt i Yy WS h h hh Sai Z SWZ UNIVERSAL v N j f K II ae CUMIN IWS Z IN X Ill T mi III W hy N l n G V N Z Y S 14470 84697 L ea a e 7 Ly y au NN Z x Z Y 0 112 dB THD N 1 khz 22 kHz BW e 0 008 dB flatness 200 kHz system bandwidth 24 bit 192 kHz digital audio lt 600 ps residual jitter e Cross domain analysis S RS Stanford Research Systems Ph 408 744 9040 www thinkSRS com Have you ever wanted an analyzer with 112 dB THD N analog performance dual domain analog and digital audio capabilities real time dual channel FFTs impulse response measurements with MLS and log swept sine chirps 200 kHz analog bandwidth jitter measurements and more but couldn t shell out the 20 000 you thought it would cost Well there s no need to wait any longer SR1 gives you all those features and many more at a price that s within the reach of the serious amateur For speaker testing amplifier measurements console testing or measuring room acoustics remember to check out SR1 A world class dual domain Audio Analyzer at a garage band price Call us or vi
45. N Register Now at CESweb org January 6 9 2011 Las Vegas Nevada A a Ce ws S gt e X PRODUCED BY ie CEA A Dual 701 Turntable Tune up New life for an audio classic an you remember what you were doing in 1975 Lately I feel lucky if I can remember what I was doing last week Re cently I decided to do a tune up on an old friend my Dual 701 turntable It pacitor that was wired across the incom ing power line I added replacing that capacitor to my to do list I was also able to download the service manual for the turntable from this site which proved to be very helpful Most of these upgrades required removing the bottom of the case on _ which the turntable rested and work ing on it from below To prevent dam age to the tonearm or switches I built a support stand from some scrap 34 thick by 2 high wood pieces to safely hold the turntable in an inverted posi Buyers Guide and the owners manual plus the unpacking and setup instruction sheets I really am a pack rat Certainly this turntable had provided a whole lot had been a reliable companion Howev er it started giving me a few problems noticeably a failure of the neon lamp that enables operation of the strobo scopic speed indicator and a reluctance of the automatic start function to move the tonearm over the lead in groove I
46. Nov p 26 Oatley Electronics K272A Headphone Amp reviewed by Aren van Waarde Dec p 39 Profiles We Interview Nelson Pass Jan Didden aX Digital May aX Visits A J van den Hul Jan Didden aX Digital Nov Receivers The Modern Homodyne Aren van Waarde Oct p 16 Eliminating Speaker Reflections with Digital Filters Richard K Mains Oct p 24 Show Reports Burning Amplifier 2009 Jan Didden Jan p 31 New York AES 2009 Gary Galo aX Digital June CES 2010 Changes Abound David Weinberg aX Digital Aug Munich Hi End Show Ward Maas aX Digital Oct CEDIA 2010 David J Weinberg aX Digital Dec Sound Solutions Trials of Finding the Music Barry Fox aX Digital May MS on Audio Demos New amp Old Wall Wart Madness Barry Fox aX Digital July Audio On The Avenue David Rich aX Digital July Audio On The Avenue David Rich aX Digital Oct Try Try Again Barry Fox aX Digital Dec Tubes 15 Watts per Channel for Less Than 150 Bruce Brown Jan p 22 audioXpress December 2010 E15 Borbely RIAA with Tubes Revisited Joe Tritschler Jan p 27 A 25W OTL Tube Amplifier Tim Mellow Feb p 12 Portable Tube Preamp Gregory L Charvat March p 16 4D32 SE Power Amp Karin Preeda April p 6 Visiting Thailand s DIY Tube Enthusiasts Karin Preeda May p 9
47. O Pacific Microphones will Manufacturered to meet IEC ANSI and ASA standards Stainless and Titanium Diaphragms Quartz insulators Aged at 150 C Try that with a calibrated consumer electret mic ACO Pacific Inc 2604 Read Ave Belmont CA 94002 Tel 650 595 8588 FAX 650 591 2891 e mail acopac acopacific com ACOustics Begins With ACO audioXpress December 2010 27 BETTIE gt ros oo The Wretched Excess AR Turntable Renovation Pt 1 Bringing a venerable classic into high end contention like turntables I mean what s not to like They grant you access to scads of software LPs which are elusive if not impossible to find on CD although I ve no real complaints about the CD format They re techno logically accessible i e you can actually get under the hood and work on them and their mechanical simplicity is ap pealing to the point of being engag ing charming even I speak here of the iconic AR Acous tic Reseach XA manual turntable a classic not only worth having but worth Bees aya 2 I A screwing around with That is what this PHOTO 1 1 An overall pepee shot of the opici table and Def rg arm The woodwork leather surfaced motorboard and scale approximately 18 x 18 are evident PY Nite ae Set ees Per aes Min PHOTO 2 A perspective shot without the outer platter The twin mator aoii and other deta
48. PM synchronous unit made by A W Haydon Co of Waterbury Conn A81378 and B81339 At a mere 1 5W it doesnt take a rocket sci entist to deduce that it doesn t generate a lot of torque or draw a lot of current which suggests that it doesn t spin off a huge 60Hz field The Haydons bearings arent any thing to write home about but they re OK The outer case is aluminum which is easier to fabricate but doesn t help out in shielding the outside world from the field generated by its two in ternal coils On the other hand torque is evidently adequate the XA passed Ed Villchur s nickel test of torque and the motor s top plate is steel which together with the internal steel bits inherent in a synchronous job con tains that 60Hz field not perfectly or completely but decently Doubling up on the motors doubles the torque and mounting two units 180 apart while still locating them fairly distant from the cartridge s arc and clear of the suspended sub chassis is easily accomplished Other than the torque the two motor drive complete ly relieves the bearing of side load No more lateral pull from the belt mucking up the bearing Instead of a force pulling the top of the table shaft one way and the bottom the other the unmolested bearing is allowed to settle in and spin in a simple uncomplicated manner Other advantages of two motor drive are probably more theoretical than real www audioxXpress com
49. Poynton www Poynton com and Raymond So neira founder CEO president of Dis playMate www DisplayMate com are regular contributors to SpectraCal s free enewsletter Silver reminded attendees that in 8 bit consumer digital video PC vid eo from black to white covers digital 0 255 while video SD and HD via TV DVD Blu ray and so on covers digital 16 235 That must be taken into account during setup if the display is used for both types of sources Many displays and Blu ray DVD players limit their digital video range strictly to 16 235 thus clipping required and al lowed headroom and toeroom His first action was to eliminate al most every display s out of the box overscan typically 1 3 which reduc es displayed image resolution by about a third sometimes this can be correct ed in the user menus but more often access to the service menus is required EG audioXpress 12 10 He then set the black level remem ber that the brightness control adjusts black level the contrast control adjusts white level using the PLUGE pattern picture line up and generation equip ment a name from long ago courtesy of the BBC Using a different pattern one with fine black lines on a white background he adjusted the sharpness to the bal ance point between softening the im age and adding artifacts which look a bit like ghosting or a glowing edge There are additional steps which are available from ISF s test disc
50. SUSPENDED COMPONENTS BEFORE amp AFTER Part Stock Mass Sub chassis 620gm 2000gm Platter inner 500gm 1200gm 980gm 980gm 120gm 120gm 200gm LP weight 225gm tonearm 180gm 350gm Totals 2400gm 5075gm Resonant frequency 3 5Hz 2 4Hz approximately Modified Mass par Nn 2 iv in P _ sn al w F Dy E ih i k d ater 2 i i tei kaqa I IC rem et 4 aoe bey rat A J gt N Te 20 oe r a Eyi ka os a t 5 kami J 3 f a ian k Wee OMI PHOTO 5 A bottom view of the completed table and arm showing the motor layout concrete backer board glued to both the sub chassis and motorboard and lead alloy flywheels on the bottoms of both bearing walls AC wiring at the rear includes the AC filter varistor surge clamps a power switching relay wire nuts and so on Goldp oint LEVEL CONTROLS For best quality and performance when it makes a difference e Precision Volume Controls e Selector Switches e Headphone Amplifiers e Passive Preamps RCA amp XLR visit us online today WUWW goldpt com ELECTRA PRINT AUDIO CO WE BUILD THE MOST COSMIC SUPERCONDUC TING FIRE BELCHING 1 7 WATT TUBE AMP ON EARTH NO THE UNIVERSE 45 Silver Stereo Amplifier Electra Print Audio www electra print com audioXpress December 2010 33 1001128110 BLO u gt9U z af lt oA i y 2 a F PHOTO 6
51. Science Founda tion ISF www ImagingScience com Display Device Calibration stepped through the basic sequence to get the most accurate image the display is ca pable of delivering Silver emphasized that the vividness of the out of the box image is designed to sell the set in the store next to its competitors and that it is not an accurate image He also said that many displays cannot be properly calibrated because of inaccurate pri mary colors red green and blue and or an incomplete set of necessary ad justments He reminded attendees that no matter what the display technology all video standards and production are based on CRI characteristics so other display technologies must be designed manufactured and adjusted to emulate those characteristics or they cannot dis play an accurate image Silver noted that content cannot be used for display calibration because PHOTO 1 XPAND universal 3D glasses MONSTER WAX 320 of the artistic license taken with color by content creators One example is CSI Miami which intentionally gives its images a golden tint Test images and test equipment are necessary for proper calibration Test images can be from a generator or a test setup disc which can be a good idea because it allows compensation for inaccuracies in the player s processing If using a generator it is best to set up the dis play directly from the generator then feed the generator to any external video
52. VAC EUX LABS REV 2 FEB 2010 2009 v ONE INCH FIGURE 2 PCB 1 copper top side Note 1 Thicker traces connected to W3 W4 W6 W7 and W8 are duplicated on bottom copper Note 2 One inch reference marks included for scaling and alignment 26 audioXpress 12 10 www audioXpress com Subsequent to measuring pin 2 of x U3 I adjusted the frequency across its x full span using the 2kQ potentiometer Total frequency range was measured at 58 48Hz to 63 25Hz The sine wave signal output of the MAX7480 filter is coupled via capaci tor C5 to pin 1 of U4 TDA7396 Power Amp Pin 1 of U4 had a measured AC voltage of 0 5V AC following adjustment by VR1 50kQ amplitude adjustment Next I adjusted the voltage on pin 1 of U4 TDA7396 to 0 1V AC I then connected the output transformer s sec ondaries to board connectors W3 and W4 TDA7396 output pins and placed a load resistance of 2kQ across the transformer s 120V AC primaries Note U4 has a protection circuit built into the output Various safety measures including overtemperature short circuit and so on are built into this amplifier see datasheet as well as a bias function that prevents the amplifier from operat ing without a proper load Caution High voltages are lethal and may injure or harm you even causing death Do not connect the output trans former without following all safety
53. adphones reduction by employing feed forward and feedback circuitry Smyth Research www Smyth Research com was back with their Realiser A8 a box with eight analog inputs and outputs that allows calibra tion of your earphones to sound quite close to what you hear from your speakers at your prime listening posi tion in two channel and surround Calibration requires very small micro phones be inserted into your ear ca nals Calibration settings can be stored on a removable SD card plus there is internal storage for 64 room listener measurement sets about 3MB each and 64 headphone listener measure ment sets about 32kB each The box and head tracker sells for 2600 3360 with a pair of Stax SR 202 headphones This is great technology for location recordists and musicians many of whom don t have studios but have had their calibrations performed at one or more of their favorite studios so they can have that sound while cre ating recording or mixing their music It has also proven useful to studio peo ple who take work home so the sound remains the same OTHER PRODUCTS OF INTEREST Disney s World of Wonder WOW home theater calibration disc is avail able in a one disc DVD 30 Blu ray 35 or two disc set packaged with Visions Inspired by Nature disc DVD 35 Blu ray 40 Much additional information is at http DisneyDVD Disney Go com disney wow world of wonder html EPILOGUE I ve reported o
54. al March Dell Ed Why Should You Change Your Sub to Digital June p 26 How Are We Doing Dec p 6 DeMarinis Joseph Book Review Current Driving of Loudspeakers July p 18 Didden Jan Burning Amplifier 2009 Jan p 31 The Cable Caddy Jan p 37 We Interview Nelson Pass aX Digital May Champagne Fidelity aX Digital June aX Visits A J van Den Hul aX Digital Nov Ferstler Howard Comparing Speakers Jan p 38 Review Swans M3 Speaker Feb p 18 Fiakas Anastasios Laminated MDF Three Way Speaker System Feb p 6 Fitzmaurice Bill E16 audioXpress 12 10 www audioXpress com The Low Profile Tuba Sept p 28 Designing Enclosures with Sketchup Oct p 36 Foster Alvin Review DPA SMK 4060 Stereo Microphone Kit March p 24 Fox Barry Trials of Finding The Music aX Digital May MS on Audio Demos New amp Old Wall Wart Madness aX Digital July Try Try Again aX Digital Dec Frane James T Review Bryston BCD 1 CD Player June p 22 Galo Gary Review PS Audio Power Plant Premier aX Digital April New York AES 2009 aX Digital June Review THAT s Balanced Line Drivers and Receivers aX Digital June Review OPPO BDP 83 Blu Ray Disc Player aX Digital Aug Review Jelco JL 45 Cueing Mechanism Oct p 29 Goeuriot Claude The Mustang Speaker Sept p 6 A Power Sin
55. alk of DMM cuts having a certain characteristic sound And by then the record companies were cutting back on LP production in favor of CDs Not daunted Teldec came up with a modified system for direct cutting Compact Disc masters DMM CD was unveiled at the Los Angeles Audio Engi neering Society Convention in Novem ber 1986 But DMM CD also stalled It proved difficult in practice to cut metal masters with a pit shape that accu rately mimics the pits produced by the www audioxXpress com conventional technique of laser cutting and etching a glass master coated with photo sensitive material The differ ence in pit shape can confuse the laser optics in some domestic players Mechanicaly cutting CD masters would now be a pointless exercise But perhaps the time is now right for some one to try DMM LP mastering again STORAGE RIGHTS If you re using a home server to store high quality audio spare a thought for a recent court case in the US The Hollywood studios have won a 4 5 million punishment payment from RealNetworks the US company behind RealAudio compression for selling 30 software called RealDVD that rips copy protected optical discs to hard disc Don t think this doesn t matter to you just because you don t want to rip video Blu ray is a very high quality mu sic disc but its AACS anti rip system and regional coding lock sound and vi sion far tighter than DVD or CD Indeed it was the promise of
56. ant Valley Dr gt In Canada rw R y K Springboro OH 45066 wu u LE Tel 800 338 0531 EER tcorcrun SOLEN pa rts express com axm baysidenet jp intertechnik de solen ca YOUR ELECTRONICS CONNECTION
57. be tween the arm and motorboard so cable load isn t a factor for me If youre using a heavier cable fix it below the center of gravity and dress it from there If stretching the stock springs to 67mm results in binding coils touching under load the fix is to disassemble stretch the springs out some more in the part of the spring that s binding and try again Stretching distance is 67 to 70mm but your springs may vary Cut and try For final leveling I use nickels around the edge of the platter I use a small round bubble level on both the motorboard and the loaded platter fid dling until both are level and I have that nickel s worth of clearance Be cause I use 4mm DIBOLD covered by leather I m looking at a pretty thick motorboard But when set up the di mensions work out fine I have about the same clearance between the motor board and platter rim as I do between 32 audioXpress 12 10 ently unstable i e tippy without the and under control The foam also damps job one is keeping the sub chassis from the motorboard and sub chassis If you crave more isolation than this setup gives you be my guest Just re member to avoid a resonance near your table s Just guessing this 10kg unit on a 5 10kg slab of stone or Corian on three Spaldeen balls sounds about right WHY TWO MOTORS Well why not What s not to like about doubling up on the motors The classic AR XA motor is a puny 1 5W 300 R
58. bearings about 211mm apart which is PHOTO 4 Jigs and fixtures Front to rear are the spare offset plate and tang for the arm I always make a spare resigned to the likelihood of screwing one up layout plate with offset an gles 35mm drilling jig 2 x 4 jig for extending the sub chassis spindle pivot distance to 293mm and the 2 x 4 fixture for hold ing the 9mm armtube without marring it while working on it fine for an approximately 230mm arm It s best really to start with two AR XA to accommodate a longer arm I cut the T bar and using a bolted in insert ex tended the bearing to bearing distance chassis for the 12 arm Photo 2 You to 293mm I was aiming for a 291 7mm bearing to bearing distance but one thing or another went wrong and I ended up at 293mm which mandated a 306mm arm instead of a 305mm arm 12 304 8mm It is crucial here to build a jig Photo 4 You want the bearings to be exactly parallel to one another and unless you use a jig youre doomed to failure The good news is by jig I mean take a scrap of 2 x 4 and drill two holes in it to ac commodate the two bearing wells the right distance apart clamp the pieces to the jig so they cant shift and you re set Start each hole using a 34 bit to a depth of about 2 then you ll need to file or sand the top out some to get a good fit The castings arent exactly
59. berg has authored articles on various phases of audio for video and film is Associate Editor of Multi Media Manufacturer www MultiMediaManu facturer com and serves as Membership OF ficer for the Boston Audio Society www Bos tonAudioSociety org and Editor of its journal The BAS Speaker Barry Fox Try Try Again reports on the audio industry as columnist for the British pub lication Hi Fi News His commentary appears in every issue of Multi Media Manufacturer audioXpress December 2010 E13 2010 audioXpress Index SUBJECT INDEX Amplifiers Preamp Muting Circuit Mike Danbury aX Digital March The BTO Dick Crawford July p 5 The Metz Preamp Reinhard Metz Aug p 5 LM12 Amplifier J R Laughlin aX Digital Oct The Brick Raj K Gorkhali Oct p 6 Power Amp Kits for Beginners Ed Simon Nov p 16 Audio Aid The Cable Caddy Jan Didden Jan p 37 Bridge to a Voltage Doubler Neal A Haight Feb p 5 Audio News aX Digital April aX Digital May aX Digital June aX Digital Sept aX Digital Oct Book Reviews Current Driving of Loudspeakers reviewed by Joseph DeMarinis July p 18 Circuit Design Tips and Techniques The Sweet Spot Nelson Pass Jan p 8 AC Filters and Other Noisy Issues Darcy E Staggs Jan p 34 Designing for Everyone Bard Kallestad July p 14 Designing Enclosures with Sketchup
60. ble speed so it can be used for all records from 33 1 3 to 90 or higher RPM The published accuracy is 0 05 or 0 1 RPM You can check _ the speed while playing a record if you provide something for the DIGIstrobo to see A small piece of reflective tape on the turntable edge will work and a supply of tape is furnished with the u unit You can also use the device to mea sure speed stability After a ten min ute or so turntable warmup press the DIGIstrobo s memory store button It automatically captures the last speed the maximum speed and the minimum speed It is pictured in Photo 4 x DO IT YOURSELF These days it s not necessary to buy a _ stroboscope disc if you have a computer because you can easily print your own x for any speed and for either 50 or 60Hz power There are two public domain programs one is named strobe exe and it s an MS DOS program which will run under Windows 98SE 2000 and XP It will print up to five strobe bands on a single sheet but the bars are a bit jagged I really recommend the other x runs on 2000 and XP Both programs are available for free from several websites including the TDL site The zip file strobe zip contains both executable programs x with documentation Figure 1 shows an example printout from strobo exe the outside diameter of the bars is over 7 w
61. ce Fs 590 H h DC resistance Re I Sensitivity 2 83 V 1m 93 dB DC resistance Re 620 Sensitivity 2 83 V 1m 87 5 dB CSISIANCES Re 3 0 2 ensitivity m 1 I Voice coil inductance Le 0 02 mH Mechanical Q factor Qms 2 5 Voice coil inductance Le 0 16 mH Mechanical Q factor Qms 4 9 Eflective piston area Sd 9 6 m2 Electrical Q factor Qes 1 5 Effective piston area Sd 119 cm2 Electrical Q factor Qes 0 36 Y 34 Voice coil diameter 29 0 mm Total Q factor Ots 0 9 Voice coil diameter q otal Q factor Qts 0 34 35 5 mm Voice coil height 2 0 mm Force factor Bi 1 8 Tm Voi hei i Aovin CI d oice coll height 17 mm Moving mass inci air m 13 49 Air gap height 2 5mm Rated power handling 100 Watt Air gap height 5mm Force factor BI 6 5Tm Linear coil travel p p 0 5 mm Magnetic flux density 1 0 T Linear coil travel p p 12 mm Equivalent volume Vas 44 8 Itr Moving mass incl air Mms 0459 Magnet weight 0 22 kg Magnetic flux density 1 17 T Compliance Cms 2 23 mm N Net weight 0 5 kg Magnet weight NEO 0 13 kg Mechanical loss Rm 0 5 kg s IEC 3 High Pass Butterworth Filter 2500Hz 12 d amp oct Net weight 1 01 kg Rated power handling 60 watt st are broker For more information or to try Samples of any SB products please contact david sbacoustics com gt gt he DA PQ Editorial HOW ARE WE DOING Il of us are dealing with some effects of the downturn We are not an exception We see these forces every day in those
62. ces More important than the product an nouncements was Speakercraft presi dent Jeremy Burkhardt s report that over the past few years more than 15 of their retail installers and dealers have gone out of business He proclaimed his outspoken belief that in order to survive the custom installation industry must be gin aiming products at a younger con sumer such as products that make lis tening to music a social escapade rather than an isolationist experience As a cor ollary he recommended that dealers and equipment manufacturers change their focus toward individuals music devices as the center of the home music system If they don t change he predicted that high end dealers will survive but mid level dealers installers will disappear He pointed to the commercial marketplace as having great potential for expansion of the custom installer business LOUDSPEAKERS EARPHONES AND RELATED PRODUCTS typically don t listen to loudspeakers at any show because of the unknown variables including the room and unfa miliar source material made an ex ception at the recommendation of as sociates and to follow up on a product had heard at CES last January Atlantic Technology s www Atlanticlechnology com AT 1 H PAS model 81 tower speakers 2500 pr sounded better balanced than my CES recollection taking into account it was in a different room with source material am not familiar with perceived a slight e
63. com XPRESSMai PHASE SPLITTER Chris Paul s letter More Impedance Tests in the October 2009 p 42 issue raises a few questions as well as interpretations x When measuring the active output impedance of a generator or m N G N F m R F D source Fig 1 varying the load is a simple and effective method Measure the voltage across a known load e1 then calculate the TO P F R O R M current il Change the value of the load and repeat the measure oor ments for e2 and i2 Then rg is equal to e1 e2 i1 i2 This method is easily applied to the split load phase splitter Figure 2 A MI T o a Ee www hs devices com info hs devices com illustrates the equivalent circuit for the phase splitter It is very A i similar to Mr Paul s Fig 1 except that the grounds are shown There are many dome connected at point A for clarity _ tweeters out there But none of them sound as dynamic as the AMT RP x Dick Olsher in The Absolute Sound 11 2008 A reference x reviewing a prominent speaker featuring our AMT 2440 RK FIGURE 1 Generator x HOLOG RAPHIC equivalent circuit FIGURE 2 Split load phase inverter SOUND DEVICES by MUNDORF This is a typical feedback amplifier note that if point A is x moved up to the top of RP it is a cathode follower and if A is T H m B F A U TY 00o moved to the bottom of RK the circuit is a standard grounded cathode ampli
64. complimentary 2 054 3 400 Total distribution 8 288 9 333 Copies not distributed 1 045 467 Total 9 333 9 800 I certify that the statements made by me above are correct and complete Publication number 787 840 Edward T Dell Jr Publisher e easiest way fo buy vacuum tu hes audioXpress December 2010 45 CONTRIBUTORS Edward T Dell Jr Editorial p 6 is editor publisher of audioXpress Voice Coil and Multi Media Manufacturer magazines Thomas Perazella A Dual 701 Turntable Tune up p 8 is the Director of Information Systems for a national retailer of professional photographic equipment headquartered in the midwest His prior experience includes work as a Criminalist in the San Diego and Long Beach California Crime Labs and Director of Marketing for a photographic wholesale distributor In addition to speaker design Mr Perazella has designed commercial high powered electronic flash equipment as well as numerous pieces of audio electronics for his own use Other leisure activities include cooking golf scuba diving and motorcycles Ron Tipton All About Stroboscopes p 18 and Vertical Cut Blending p 36 has degrees in electrical engineering from New Mexico State University and is retired from an engineering position at White Sands Missile Range In 1957 he started Testronic Development Laboratory now TDL Technology Inc to develop audio electronics During the 1960s and 70s TDL built a
65. ctive filters and pseudo random noise generators for well known companies such as Distributor Wanted 46 audioXpress 12 10 Bose Corp and Acoustic Research He is still the TDL president and principal designer Joel Hatch Turntable Speed Control p 22 served in the US Navy from 1975 1981 as an electronic technician nuclear He then attended Ohio State University receiving a BA in biochemistry and an MS in nuclear engineering instrumentation While working at OSU s reactor lab Mr Hatch completely renovated and updated the reactor s safety and control system s old 50s 60s era tube nuclear electronics into solid state ICs In 1993 Mr Hatch left OSU and worked several years for the Air Force developing test methods and procedures for electro optic components used in air and spaceflight with emphasis on nuclear survivability Mr Hatch returned to Ohio in late 1997 and continued to work in the fields of space and satellite technology evaluating and testing electro optic and solid state analog digital mixed components for use in cosmic radiation environments Currently Mr Hatch works as a reliability engineer for a large telecommunications company developing tests and verifying operation of telecom amplifiers in extreme environmental stress conditions and continues as a consultant in the nuclear and space radiation effects field D42 1 DIY Kits 2 way design www audioxXpress com W passiv
66. cy lindrical they taper slightly You ll also need to cut into the jig to clear the flanges that are cast into the T bar so the web sits flush against the wood x I should mention that a drill press makes easy work of getting two good parallel holes And if it isn t obvious the holes go into the narrow 2 face of the 24 x Once you have a satisfactory jig you can clamp the two sub chassis pieces to it and have them welded together The offset angle approximately 24 But jig will keep everything aligned despite _ the heat of the welding If youre making do with one sub chassis as I did either you re dealing with two welds or you re bolting in a splint the jig is equally vital LAST Record Preservative Record Preservative F OL WAK AR FOR AL AS ATH OR APT C ANDUN gt FUND OUNCES g TSA Er L A Hear Ye Hear Ye LAST THE LAST FACTORY 2015 RESEARCH DRIVE LIVERMORE CA 94550 3803 925 449 9449 FAX 925 447 0662 www lastfactory com audioXpress December 2010 29 ABOUT THE BEARING The AR bearing is a hard plastic disc at the table spindle which is machined on 0 08 radius The sleeve isn t as tight as Td like the plastic disc can slide about and as smooth as I d like What to do First take both plastic discs from the table and tonearm wells Choose the one with the most pronounced dent in it and clean it and the bearin
67. d ucts we offer a simple and easy return policy If for any reason you re not com pletely satisfied just return the cables undamaged within 30 days and we ll refund your purchase price in full 3D HD 3D TV What You Must Know was Michael Heiss s approach to explaining in home 3D video s his tory status and idiosyncrasies 3D is here whether we like it or not and is a world wide phenomenon Heiss recom mended Mark Schubin s website www E4 audioXpress 12 10 SchubinCafe com as an excellent source of information on video including 3D There are issues with 3D as a concept independent of the implementation Vergence the distance from the viewer where both eyes point to place the object see http en Wikipedia org wiki Vergence versus the focal distance the dis tance from the viewer s eyes where they focus to a sharp image when these don t match nausea has oc curred The conflict comes from the eye focusing at the screen while the stereoscopic image tells the brain that the object is either in front of or behind the screen Changing your viewing angle changes the 3D effect because the left right image spacing changes with angle The among people thus altering the ef interocular distance varies fectiveness of the stereoscopic ef fect Approximately 7 of the popula tion can t see stereoscopically Sports and movies will take the lead in developing 3D conten
68. d to circuit ground The result ing Faraday shield has strongly reduced its tendency to pick up spurious signals In the shielded cabinet hum induction no longer oc curs Yet the use of mobile phones in its close vicinity results in an audible signal Shielding has not abolished the sensitivity to powerful RF signals probably because the intercon nects or the headphone cord act as antennae Third the use of batteries limits the time of operation Oatley specifies that when you use alkaline cells 2 AA for the heaters and 1 E block for B the AA batteries will last 250 and the E block 70 hours It is of course possible to use six series connected AA cells rather than an PHOTO 1 The Audio Technica AT3060 tube microphone e ee ap a ye Af Bae i PEE a Pee A E 3 VY 2 te ope a purpen Foe ee PHOTO 2 K272A circuit board Note the rubber grommets used to dampen valve microphony The AA cells on the PCB supply power to the heaters The additional 9V battery is not visible o i i Y OPPO Digital Inc www oppodigital com se Blu ray 3D SACD DVD Audio Streaming Dual HDMI and More The Future of Universal is Multi Dimensional For product information and availability please visit www oppodigital com 650 961 1118 New Blu ray Player COMING SOON 2629 Terminal Blvd Suite B Mountain View CA 94043 audioXpress December 2010 41 E block which wil
69. d were never designed with sound in mind This is a truly great DIY piece of gear The Burson Audio modules dramatically exceed the performance subjectively and objectively of any monolithic IC bosed op amp period Not only is the distortion low but the higher order products the ones that sound bad are almost immeasurable Featuring a sophisticated Voltage Differential Amplification network audio grade transistors sore at ha n RBI 1 resistors gold plated pcb meticulous hand Y ZK N assembly and stringent testing burn in amp matching In pro use these discrete Op ERO procedures these modules are without peer amp modules should be a great Dual Discrele Op Amp Modis single microphone preamplifier a BURSON 71486 Discret For more info on the Burson Audio discrete op amps Ed Simon AudioXpress October 2009 914 Spa ae ee http www partsconnexion com t Index burson_opam1_ htmi Clock Modules Series 2 Super Regulators BURSON 72012 locks Available in these Frequencies LM7815A 15V 250ma REGULATOR adjustable 10 20V k sa 49 95 USD ea 11 2896 mHz 16 9344 mHz BURSON 72762 24 5760 mHz 5V 250ma REGULATOR adjustable 3 9 27 0 mHz 49 95 USD ea 33 8688 mHz 1 BURSON 72015 SENEE ane spt 15V 150ma REGULATOR adjustable 10 20V BURSON Clocks 119 95 each V cloc To see the Burson Series 2 Regulators We Sent yola on ree Ree qea
70. device applications and standardized HDMI cable labeling Category 1 cables will be labeled Standard and category 2 cables will be labeled High Speed For ARC and or HEC to work all of the equipment connected together must support the feature HEC re quires special cables ARC and or HEC might not be supported on all ports on a given product www audioxXpress com Another HDMlv1 4a optional capa bility is consumer electronics control CEC it is not a replacement for home networking it either works or not and what it does will differ among products depending on implementa tion The next HDMI version is under development but is not expected to be released for about two years The Digital Entertainment Content Ecosystem DECE has introduced UI traviolet www UVVU com a brand name for the consortium s cloud based digital rights management DRM sys tem Users will be able to create an account in which to store their Ultra violet licensed digital entertainment content then access it from all their de vices anywhere anytime The system is not yet ready for prime time however the major studios and TV networks have signed up Motion sensing control for gaming similar to motion sensing light switch es but much more sophisticated has arrived no hand held or worn control ler is necessary This technology pulls the gamer off the couch to provide physically active interaction with the game on the scree
71. dge to the midfrequencies plucked guitar strings didn t sound right and cymbals sounded a bit constricted The male voice and tenor sax sounded OK but the piano didn t sound natural still think the bass is too strong but it should be marketable The H PAS tech nology incorporates an internal bass trap and a vent to get more apparent bass from two 5 25 midrange woof ers with the range above the 2500Hz crossover frequency coming from a 1 silk dome tweeter They claim that the 3dB low frequency point is at 31Hz The model 82 is a smaller version for which they claim a 39Hz 3dB point from which heard too much low end to a female singer s voice and a some what boxy sound Sandy Gross has founded his third speaker company GoldenEar www GoldenEar com Gross had made quite a name for himself over the decades having cofounded Polk Audio in 1972 and been the key designer for some of its most respected speakers He repeat ed that accomplishment by cofounding Definitive Technology in 1990 serving as its president until he retired in 2009 Circumstances and his enjoyment in de signing speakers led to the creation of GoldenEar which offers seven models two of which are horizontal versions of two others and three different 5 1 channel systems with and without separate powered subwoofers 1750 3500srp All of the products are de signed and engineered in North Amer ica but built in the Far East In the US
72. did not ro tate at 33 1 3 RPM I looked into ad come with a speed or pitch adjustment to set the running speed for 33 1 3 RPM Although VPI www vpiindustries com offers an accessory power control ler to provide this function the price was a bit steep I decided to design and plying the motors rated output power and driving a step up transformer I would bust and reliable over the years for gen Substituting a resistor to simulate a load and an old transformer I had lay _ ing around I went through a few itera tions of the circuit design to prove the concept and ensure the output was a pure sine wave and free from noise with minimum harmonics After prototyping a few other application notes using the same method scheme for generating build a variable frequency AC supply to control the turntable s speed rather than use a Triac or similar type of solid state control circuit Although these circuits are readily available at the hardware store they are prone to generating noise that may be picked up by the cartridge I consulted my notes from sever al years ago when I rebuilt a General Radio Model 1311 A Audio Oscilla RadioShack AROW INVEATEA PHOTO 1 Radio Shack inverter 22 audioXpress 12 10 tor This circuit with minor modifica tions formed the basis for designing and x building a Variable Frequency Synchro nous Motor Controller VFSMC suit ab
73. e Authority on Hi Fi DIY No matter what your requirements are re pcx has what you r need Whether it be vacuum tubes NEW New Old Stock or O sockets transformers capacitors resistors connectors hook up wire etc Visit our new e Commerce website and sign up for our eConnexion Newsletter sn E nX cop MEN EAT Bamon EBS Ar Wt di u www partsconneXion com TT audioguest PS TAKMAN m CADDOCK order partsconneXion com ee MW C oncuran CNS ie coe i AR H oe B Beaty QUN punin 0 A a I ONSEN ie S krAudio f MultiCap International Audio Group Ren pae agence VIBRAPOD Marineo We ve got a world class selection of all the best brands dnd more arriving every month AM Toll free order line 1 866 681 2602 Tel 905 681 9602 Fax 905 631 5777 r pe Paypal US money order bank draft cashier s check REAG NEGTECH FURUTECH ELMA Hiie We s jaaaj Pe CHAKO e Jennsen Sea amp 5109 Harvester Rd Unit B2 Burlington Ontario Canada L7L 5Y4 te w a is W Se M a Deam iar Sta a bladed screwdriver to start lifting each damage the underlying particleboard Be cause the signal leads are attached to the process Photo 4 shows the open inverted turntable resting on the stand Whenever I disassemble a component for which I don t have assembly draw FIGURE 1 Power supply schematic 10 audioXpress 12 10
74. e Generator for Turntables Nov p 10 Gorkhali Raj K The Brick Oct p 6 Haight Neal A Bridge to a Voltage Doubler Feb p 5 Hansen Chuck Measurements for OPPO BDP 83 Blu Ray Disc Player aX Digital Sept Hatch Joel Turntable Speed Control Dec p 22 Johnson Rich Low Frequency Horn Speaker Sept p 18 Kallestad Bard Designing for Everyone July p 14 Koonce G R Tang Band Full Range System May p 4 A Tang Band 3 System Aug p 23 Laughlin J R LM12 Amplifier aX Digital Oct Levkoff Keith Review Personal Digital Recorders Part 1 March p 10 Review Personal Digital Recorders Part 2 April p 14 Review Personal Digital Recorders Pt 3 aX Digital Sept Lyle Tom Review Lehmann Black Cube SE Phono Preamplifier April p 26 Review Emotiva XPA 2 Power Amplifier July p 24 Mains Richard K Eliminating Speaker Reflections with Digital Filters Oct p 24 Mass Ward Munich Hi End Show aX Digital Oct Mellow Tim A 25W OTL Tube Amplifier Feb p 12 Metz Reinhard The Metz Preamp Aug p 5 Morton Cornelius Stuffing and Sound Speed April p 12 The Split Load Phase Inverter Revisited Nov p 20 Nousaine Tom Review Dayton T1503A Subwoofer Feb p 23 Review JBL LSR6325 Biamplified Studio Monitor Nov p 26 audioXpress December 2010 E17 Pass Nel
75. e equations for the cartridge outputs are the same for both the lateral and vertical cut cases a mathe matical analysis will not be helpful Instead we looked at the mechanics of the two cases to arrive at a hypoth esis that may explain why LR blending does not provide any benefit for vertical cut records This is illustrated in Fig 5 38 audioXpress 12 10 VEE GROOVE probably be different Hence LR blending may produce a definite noise null depend ing on the physical condition of the disc We hypothesize that the key point here is the angle the stylus makes with the groove wall Pos sibly the output noise is proportional to the track 1000 Frequency Hz FIGURE 4 Comparison of LR blend at the center position lower line with the one o clock position Ortofon cartridge with turnta ble connected directly to 4010 inputs The Ortofon cartridge has very good channel balance Ina lateral cut recording the grooves are vee shaped The pickup stylus rides on the two groove walls which contain the left and right signals plus cutting and playback styli can move signals will ideally be the same while the left and right noise signals will noise With a mono record the music Headshell Terminal pins x Tracking force on groove wall is proportional to sine a Is the groove wall noise also proportional to sine a FIGURE
76. e radiators Tom Yeago The Wretched Excess AR Turntable Renovation Pt 1 p 28 who obviously has too much free time reports that he has been a buff since puberty or thereabouts A Virginian the Shenandoah Valley Tom s formal training is in economics a k a the dismal science Besides noodling about in hi fi matters he also devised a complete reorganization scheme to fix the shamefully inadequate public school system in case you re interested Don Walizer Vertical Cut Blending p 36 resides in Arizona Aren van Waarde Review Oatley Electronics K272A Headphone Amp p 39 is a biochemist working in the field of medical imaging positron emission tomography He has worked as a Ph D student and a postdoc at several universities including Leiden and Yale Universities before accepting tenure at the University of Groningen His passion for audio started on his ninth birthday when his parents gave him a Philips kit Most of his current audio equipment loudspeakers radios tuners pre and power amps both tube and solid state is homemade DED CEDIA 2010 Value on Display in Inree Dimensions By David J Weinberg EDIA www CEDIA net claimed 20 00 attendees the audited count is not yet available com pared with 22 000 last year and that al most 20 of the attendees were at their first CEDIA which means that many who attended last year did not return These numbers included
77. e slightly different Indeed no ticed that identical tubes showed a 15 to 20 difference in anode current in the V1 and V2 positions The resulting difference in voltage gain between both stereo channels can be easily trimmed away by carefully adjusting in put potentiometers VR1 and VR2 Yet the dif ferent bias could result in different distortion characteristics of the left and right channels 2 questioned the rationale of the design What s the use of valves running at 9V B and anode currents of 10 to 15uA Will such valves not sound as noisy transistors And what s the use of a class A triode stage fol lowed by a class AB CMOS chip Will the sonic advantages of the triode if any not be offset by the sonic disadvantages of the solid state circuit odd order harmonics 3 Finally will such battery valves not pro duce huge amounts of harmonic distortion The 6418 is not very linear Tung SolClike Raytheon a manufacturer of these tubes specifies a total distortion of 12 yes twelve percent at the standard operating point However similar designs valve stage run ning at low B plus solid state output buf audioXpress December 2010 39 fer circulate on the Internet They appear to originate from Korean headphone enthusiast Shin Jeob Shin nicknamed Sijosae but were tried by many others including audiophiles from the US and Germany In Germany the circuit topology is known as the YAHA amplifier the
78. e third annual Pre Game Show featured the dynamic duo of Michael Heiss CE industry consultant and mem ber of CEDIA s technology council and Richard Green integrator and director of CEDIA s technology council During this preview session Heiss and Green discussed the show s purpose and what to look for on the show floor to keep the custom installer integrator busi nesses healthy and profitable These businesses need to focus on what they can offer that justifies the extra cost at a time when most of the equipment is commoditized and the economy has severely limited corpo rate and personal discretionary expen diture Businesses need to effectively aim at the right market Custom install ers can install those readily available boxes and set them up to deliver the multimedia experience that the con sumer can t get by himself Heiss Green agreed that for survival and growth custom installers integra tors should focus on retrofits com mercial jobs and energy management Green said Energy is the new audio and is what s changing our industry audioXpress December 2010 E1 Heiss added that achieving higher green credits for the homeowner will require looking beyond energy efficiency to other product aspects such as pack aging and installation elements all of which can add or subtract LEED points For A V and whole home control and automation there were many iThings and Android based touch pads and apps
79. ed RAID to prevent content loss and if the whole server is stolen the owner can cancel its credit authorization and download the pur chased tracks again But the music is MP3 at 320kbps or below which is CD quality or below So the option to rip is vital The key difference said Imerge about the server is the new Blu ray drive which also allows users to store and play back content from Blu ray discs The integral drive reads content from CDs DVDs and Blu ray discs to store on hard drives for convenient access Is this legal though We ship the product without the ability to record as the manufacturer cannot be seen to be actively advo cating 3rd party software that can be construed as contentious We run a comprehensive certification program for our dealers and partners world wide which runs through the setup and installation of the product Part of that installation training walks the dealer through adding 3rd party software on behalf of the end user Once this is complete the unit is then ready to rip DVDs from the slot loading drive and also Blu Ray in the same manner Imerge reckons that Real came un stuck because the company took a CSS license and the ripped copy was still protected Because the Imerge server does not come with pre installed rip software it is legally clean as sold Although dealers and custom installers may advise customers on the installa tion of ripping software
80. eks This article offers a description of the K2 2A my experiences in wielding the soldering iron and a subjective evaluation of the sonic results K272A Circuit The schematic of the K2 72A Is shown in Fig 1 As you will notice the actual amplifier cir cuit is quite simple but a few compounds have been added to provide DC power to the tube heaters and the output buffers The gain stage of each stereo channel con sists of a single 6418 wired in triode mode V 1 and V2 Wired in this way a 6418 will provide a voltage gain of about Because the valves run at very low anode currents between 10 and 16uUA they are not capable of driving headphones directly The amplified signal at FIGURE 1 Schematic of the Oatley Electronics K272A their anodes is therefore fed to a stereo head phone driver chip utilizing CMOS technology IC 1 This compound is configured as a unity gain buffer Because it combines a high input impedance with output current drive capability the preceding 6418 gain stage is hardly loaded and you can connect headphones with imped ances of 8 to 80Q to the output terminals Volt age amplification is provided by the valves and current amplification by the integrated circuit The 6418 tube is a directly heated pen tode designed for low anode voltages 30V maximum and low power consumption The valve heater requires only 10mA at 1 25V For this reason and to eliminate mains induced noise Oatley Electro
81. el discus sion was moderated by Michael Heiss Jim Chase HDMI Licensing director of technology www HDMI org Eric Bodley Perfect Path s consumer elec tronics VP and GM www PerfectPath com John Marshall Wireless HD Con sortium chairman www WirelessHD org Leslie Chard WHDI president www WHDI org and Mark Stockfisch Quantum Data VP and CTO www QuantumData com discussed and de bated various problems and solutions Heiss declared that despite claims for DisplayPort which is primarily for computer system applications HDMI is not in danger of extinction Chase emphasized that for each piece of equipment such as a Blu ray player A V receiver or display it is more important to understand which HDMI features are supported than the version ID This is especially true since the release of HDMI 1 3 because the specifications for that and newer ver sions include optional functions many of which are not included in a manufac turer s model by choice giving manu facturers a way to manage the costs of their products and differentiate them from those of their competitors It also can easily cause two products to legiti mately claim compliance with the same HDMI version but be incompatible be cause optional features needed by one are not supported by the other This problem led to a change so that by the end of 2010 HDMI version IDs will no longer be used instead employing lo gos to identify the speed and op
82. eliver up to 1100nits 321ftL which is necessary for outdoor viewing The pavilion housed a custom built home theater about 16 D Box motion chairs a Digital Projection 2D 3D projector a Stewart screen XpanD 3D glasses a 9 1 channel au dio system and more to give attend ees a taste of the possibilities the im age looked nice but the sound was far too sibilant Procella Audio www Procella Audio com and THX sponsored a small THX certified screening room that was built off site by Epic Home Cinema then dismantled and resur rected on the show floor believe it housed two rows of five large leather bound seats they can scale the room design from 2 40 seats Sitting in the front row right seat the sweet spot was second row center heard too much bottom on voices and too much A strummed bass didn t sound realistic sibilance Da lite and Joe Kane Productions JKP www www DaLite com VideoEssentials com have expanded the JKP Affinity screen series to three models with gains of 0 6 0 9 and 1 1 The smaller the screen the more con centrated the light from the projector so a lower gain screen should be used to keep the black level down resulting in higher effective contrast Also if a digital cinema projector which gen erates much more light output than a home theater projector is used a lower gain screen is necessary even for large screens to keep the black level down to an acceptab
83. ely AudioBytz is our new newsletter free to anyone interested in excellent sound David Ranada is one of the most in formed and experienced commenta tors on the audio scene anywhere Go to our website www audioXpress com and join the thousands who are reading David every other Thurs day Watch for a new blog from the publisher on life here at Audio Ama teur We have a lot going on in this 40 year old enterprise dedicated to hands on audio craftsmanship Blogs require snappy titles so we decided on Ed Dell s deciBels Watch for an an nouncement on our website A lot more than I have detailed here is going on in our corner of Peterborough I ll be sharing a lot of that in my im pending blog E T D JANTZEN AUDIO DENMARK realize your audio dreams using Jantzen Audio Z caps Superior Silver and Silver Gold www jantzen audio com 6 audioXpress 12 10 www audioXpress com t Pie MEET THE FUTURE AND NEW MARKETS gt y The International CES is the trade only event that sets the stage for consumer spending all year See what they can t live without and what will drive your bottom line from 2 500 of the most innovative global companies Register with priority code M1 by 5 p m EST December 31 to save 100 off the on site registration fee tional Exhibitors Reach an international audience in one trip Reserve space at Exhibit CESweb org THE GLOBAL STAGE FOR INNOVATIO
84. ember 2010 35 WeWPIIII G IXIYIIIIIIIISHMIAI IK By Don Walizer and Ron Tipton Vertical Blending Can a blend control help vertical cut recordings MODE L R MONO L R VERT LR BLEND DISABLED 6 EXT CONNS ENABLED LR BLEND LEFT The Restoration Preamp PHOTO 1 Model 4010 front panel showing the Mode and Blend controls he TDL model 4010 The Res toration Preamp Photo 1 has a control a single turn po channels for lateral cut records This fea ture which you select with the mode switch can help maximize the output signal to noise ratio S N because the tentiometer for blending the x playback signals from the left and right noise from the left and right groove walls is usually not the same We Don and I have been asked whether a blend control x is useful for vertical cut records In both cases a stereo pickup is used to play a mono record This article describes our x and the HF filter to 24 The pickup cartridge outputs will in both cases be S N and Sp Np mode control set to L R mono or LR blend With the wide groove records non Edison a setting of 10 from the center of the LR blend control had no discernible effect on the noise or dis tortion As I rotated the control further to the right or left the sound became noisier but there was never a change in perceived distortion In all cases full left and full right settin
85. en you that direct the light to the strobe pattern printed on the bottom of the platter and ment for the neon It would probably outlast whatever life was left in the turn table However that would require a power supply and additional circuitry Photo 19 Clean all the parts and lubri that would not only add complexity but _ cate the hinge pins and cam surfaces with return the image to the viewing window The assembly is fastened to the turn table by two screws that also provide for mounting in two positions one for op eration at 60Hz and the other for 50Hz Removing the cover gives access to the lamp Once the cover was off I lifted the lamp from the clips that held it in place ubiquitous NE 2 lamp would work as a substitute I had quite a few in my x Mounting the NE 2 replacement in the housing turned out to be easier than er PHOTO 18 Automatic start actuator I expected I first positioned the lamp in the housing at the appropriate location port and placed it right side up on the base I replaced the platter and the car covered with shrink tubing leaving only tached After releasing the lockdown inserted the lamp in the housing being the cartridge tracking force and anti skate setting plugged in the power cord the project and measured the required lead length The leads were trimmed tinned and the ends to be connected exposed I then
86. ention to cies for the arm cartridge combination while at the same time reducing sensitiv detail may very well return an old friend to former glory aX audioXpress December 2010 17 All About Stroboscopes Use a stroboscope disc to determine whether your turntable Is set to the correct speed serens POS OTT Sle ae ee el r s ALO RN an FO 8 Y Be ag 5 4 7 D SI AA 77 Bee a On Or ee oes Be cee he ee ee z Aana aa ee ep LOPETA gene A ar ee PPE R BRI SL 2 gt gt ES ES b A ara pon s z gt 6 se b D Cu W K E W 7 rL z ae os ese ge ai M i Se lt ESS a lt Stee SMM p l NWI a SAW Za K K WW 7 sss eer NENEA O SSS EBX s II_ x0NS T 2 ec wass WS PHOTO 1 Commercial stroboscope discs The Esoteric Sound disc is shown right rear o a phonograph turntable user a stroboscope is a paper or cardboard disc with a spindle hole in the center that you can put on the turntable to measure its ro tational speed This works with alter is mP mF P et piid ilk k nSu E i Yf on MAALAA and the pattern of bars on the stro current DC lighting or with sun light u a PHOTO 2 The KAB SpeedStrobe Instead of bars this disc has the rotational speed numbers printed on it The 60Hz light source limits its use to 60Hz powered turntables 18 audioXpress 12 10 www audioXpress com Strobosc
87. er had a measured AC square wave operating frequency of 15 962kHz x Pin 2 of U3 input MAX7480 Filter had a measured AC Voltage square wave signal of 1 25V AC at a frequency of 62 25Hz PHOTO 4 Frequency adjust potentiometer mounted to endcap and circuit board KOUNTEK Fountek is well known for its line of high end ribbon tweeters which are used in many commercial speakers and DIY kit speaker systems worldwide In expanding its offerings Fountek has developed a line of full range drivers This line of speakers has become instantly popular and has drawn the attention several online DIY web sites and discussion forums Fountek is a perfect choice for any little speaker project FR88EX 3 Full Range Response from 100Hz to 30 000Hz FR89EX 3 Full Range Neodymium magnet 4 or 8 ohm Response from 70Hz to 20 000Hz FR135EX 5 Full Range Neodymium magnet Response from 50Hz to 26 000Hz Complete specifications and curves are available from our website at www madisound com Madisound Speaker Components Inc P O Box 44283 Madison WI 53744 4283 U S A Tel 608 831 3433 Fax 608 831 3771 info madisound com madisound com audioXpress December 2010 25 PHOTO 5 Motor controller no 8 countersink hole for securing TDA7396 to heatsink visible on right side and frequency adjust knob visible on front PHOTO 6 Top view of controller AC SYNC MOTOR CONTROLLER 55 65Hz 98 115
88. exhibitors and members of the press The show floor with more than 450 exhibits 90 were first time CEDIA ex hibitors was never heavily crowded According to reports many dealers and custom installers were searching for ways to expand their businesses be yond their core offerings About 150 courses were offered with a special deal instead of paying for each course you could attend all the courses you wanted for 400 About a third of the courses were business re lated covering all facets of how to build and manage your custom installer busi ness such as design management cus tomer documentation how to relate to and work with customers architects builders interior designers and so on customer service social networking and selling What Women Want Selling Home Entertainment Systems That Benefit Her Lifestyle Technical courses included basic math for technicians various aspects of home theater and home control design build adjustment certification prep courses wired wire technician less technologies troubleshooting AC power including grounding and condi tioning and more attended about half a dozen none of which had atten dance as large as perceived at previ ous CEDIA Expos learned that a second edition of the CEDIA Technical Reference manual is under development strongly suggest waiting until that second edition has been released See my review of the first edition in the May
89. ey Electronics www oatleyelectronics com which sells electronic parts and used equipment in New South Wales Australia has launched a small range of audio kits based on tube technology My interest was raised by glowing reviews written by Mark Houston DIY convener of the Melbourne Audio Club1 The kits employ subminiature valves pentodes type 6418 made in the 1970s by the American company Raytheon for military purposes use in cryptographic equipment 2 Such valves have also been employed by the Royal Dutch Navy and as outdated navy stocks are sold by local dumpstores at rock bottom prices many 6418s ended up in my junkbox intended to use these tubes for building a regenerative receiver but never considered them for audio purposes until discovered the Oatley products Currently the following vacuum tube kits are available K261 Tube Preamplifier single gain stage for piezo transducer e g of elec tric guitar AUS 22 K270 Tube Preamplifier like K261 but dual gain stage and volume control AUS 29 K272A Stereo Tube Pream olifier Headphone Driver AUS 30 K281 Tube based 5 1OW Power Amplifier AUS 29 and K282 Tube based Stereo RIAA Preamp AUS 47 ordered the K272A and the K282 The website allows secure ordering by credit card Customers are treated courte ously by first confirming receipt of the order and receipt of payment and then sending the goods with package number My kits ar rived within two we
90. f you never play 78s u number TT RB 06H 12 A similar tubing but with a 0 405 OD is available from McMaster Carr 9630 Norwalk Blvd Santa Fe Springs CA but 78s were recorded at so many differ ent speeds that multi speed strobe discs or a DIGIstrobe is essential How important is it to set the speed while actually playing a record That is how much does stylus drag slow the 530400 Lake Park FL 33403 800 652 6733 Www mpja com speed With today s high torque motors and low tracking force cartridges the answer is probably not much Perhaps if you have golden ears you can hear the difference but for most of us all we need is to get the speed as initially close as we can ax 14 white LED Array FIGURE 2 White LED array strobo scope lamp Drill a 34 diameter hole and ream it slightly larger to mount the array Epoxy the array plastic case to the PacTec enclosure he Splatter rim are useful at 33 1 3 and 45 RPM only If the turntable plays 78s you will need a way to measure the speed REFERENCES You could also build a multiple neon lamp but the lamp firing voltages are x ton IL 60189 630 933 9801 www esotericsound com 1 Esoteric Sound 1608 Hemstock Ave Whea 2 KAB Electro Acoustics PO Box 2922 Plain 3 Contact Music Direct for Clearaudio prod x ucts 318 N Laffin St Chicago IL 60607 www musicdirect com 4 Contact Mu
91. fier as shown it is a feedback amplifier To O F M S C E n determine gains plate or cathode currents and output imped e Ludwig v Beethoven ances some things need to be defined 1 B feedback factor B RK RK RP Negative feedback B is negative Rit total plate load Rit RK RP A gain without feedback A u Rit rp Rit A gain with feedback A A 1 B A Because B is negative the denominator is more easily written as 1 B A Ak cathode gain Ak A B plate gain is then Ap A Ak In a triode when grid current is not drawn ik ip ek cathode voltage ek ei Ak and ep ei Ap ik cathode current ik ek RK ip ik c PY co I o o This will allow a full low frequency evaluation of the phase inverter at the plate current and voltages that the tube charac teristics are given For example using the characteristics given x for a 6SN7GTB u 20 rp 7700Q and gm 2600S With RP 10000Q RK 10000Q and ei 10V x 1 RK RP 100000 2 RK RP 90000 i i k nn b x MCap Supreme Silver Gold Oil 2 A 1444 2 A 14 0078 3 1 75669 3 A 1 750124 2 OE eam tag 4 Ak 0 878345 4 Ak 0 875062 5 Ap 0 878345 5 Ap 0 875062 6 ek ep 8 78345V 6 ek ep 8 75062 7 ik ip 8 78345 104 a 7 ik ip 9 72291 10 a 2009 s Global Premium Capacitor Comparing the cathode or plate voltages of 1 and 2 t
92. fine when a signal is 3 available but is useless when it isn t as with x amplifier inputs The solution that works for both inputs and outputs is to shut off all sig x nal sources and to then route a test current x signal through the circuit points under test The ratio of the voltage that arises across x those points to the test current is always the impedance between those points aX STATEMENT OF OWNERSHIP MANAGEMENT AND CIRCULATION Required by U S C 3685 Date of filing September 30 2010 Title of Publication AUDIOXPRESS Publication Number 1548 6028 Frequency of Issue Monthly Annual Subscription Price 50 00 Location of the headquarters or general business offices of the publisher Audio Amateur Inc PO Box 876 Peterborough NH 03458 0876 Publisher Edward T Dell Jr PO Box 876 Peterborough NH 03458 0876 Assistant Publisher Dennis Brisson PO Box 876 Peterborough NH 03458 0876 Owner Audio Amateur Inc PO Box 876 Peterborough NH 03458 0876 Stockholders owning or holding 1 percent or more of the total amount of stock Edward T Dell Jr PO Box 876 Peterborough NH 03458 0876 Known bondholders mortgages or other securities None Average copies each issue during preceding 12 months Single nearest to filing date Total copies printed 9 333 9 800 Mailed Subscriptions 3 220 2 832 Sales Through Dealers Counter Sales and other Non USPS distribution 3 014 3 101 Free Distribution
93. g HDCP v2 0 and presum ably audio to displays throughout the home from the WHDI website They claim lt 1ms latency end to end audioXpress December 2010 ES The WHDI website clarified the dif ference between WHDI and DLNA Digital Living Network Alliance trade organization WHDI and DLNA are complementary protocols DLNA de fines the delivery of compressed media over an IP network wired or wire less whereas WHDI enables delivery of uncompressed HD content video from HD video sources such as gaming consoles PCs BD players and set top boxes to displays In both cases wire less latency might become an issue for time sensitive interactive applications such as gaming There was no discussion of how the consumer can select an HDMI cable to ensure it will work Some assurance can be inferred from the presence of an official HDMI logo on the cable but that still doesn t prove that the length of cable purchased was compliance tested There have been cases where a shorter length cable passed compli ance testing and the certification was extended by the cable manufacturer s marketing to all lengths in that series A source of reasonably priced possibly well made HDMI cables and adapters is Blue Jeans Cable www BlueJeansCable com They use Belden Canare or Tartan cable clearly iden tifying which for each product having the assembly performed in China From their website As with all of our pro
94. g wall to remove every trace of oil Soak both overnight in rubbing alcohol and clean again You want to fix the disc on the bot tom with the dent exactly in the center so that the shaft rides without touch ing the sides at least on the bottom How With RTV silicone hi tempera ture gasket maker available at any auto parts store in 3 35 oz tubes for about 7 Im partial to Permatex s Ultra Black which ll do the job happily oblivious to the oil Now you just need to get the disc down there centered I use the bearing shaft for this silicone on the end of an unsharpened pencil and dab it on the bottom of the Nye Sik RW 4 well Then stick the dented side of the bearing disc to the eraser dab another the bottom of a babbitt sleeved well filled with oil into which fits the steel post of _ the disc on the bottom of the bearing well the bottom into a round nub of about mote of RTV on the undented side of the dented side up Next drop the inner plat The next item on the bearing agen FIGURE 1 Modifying the main bearing First locate the dimple on the plastic disc exactly in the center with some Teflon thread sealer tape and silicone RTV Next eliminate any clearance at the mouth of the bearing by deforming the lip 30 audioXpress 12 10 www audioXpress com top of the sleeve constricting the bear ing The sleeve is about 3 8 so you re looking for a ball of about 0 75
95. grease I used Panef white lith modern lubricants that will work as well components I had to release the tone arm to do this All of the mechanism is driven through a large plastic cam wheel connected to a gear at the bottom of the PHOTO 10 Cam wheel rest position 12 audioXpress 12 10 PHOTO 9 Lubrication points motor assembly Photo 10 At rest the cam wheel sits with an open space in the the actuating levers is shown in Photo 12 teeth opposite the motor gear To begin operation while the motor is running a pivoted arm on the cam wheel moves against the motor gear _ which rotates the cam wheel to a point _ where its teeth engage the motor gear It will continue to rotate until it again reaches the rest position where there are drag on the tonearm It originally was no teeth During that rotation depend ing on the function selected levers move through various slots in the cam wheel I will not try to describe all the move ium grease I am sure there are many other cause you can see them in action better Before beginning the disassembly of the turntable I manually ran it through its cycles while watching the action of the ments for the different conditions be than I can describe them a C clip as shown in Photo 11 After re moving the wheel I cleaned the old grease www audioXpress com from the wheel and applied a new lubri cant The bo
96. gs sounded identical These listening tests gave no support at all to the need for a vertical mode blend ing capability at least for wide groove x records effort to answer this question 10000 20000 Frequency Hz FIGURE 1 Comparison of L R mode with LR blend control at the center 12 o clock position Stanton cartridge and utility amp The difference between the graph lines is because the LR blend gain at the center position is 1dB lower than L R 36 audioXpress 12 10 www audioXpress com where S is the signal and N is the noise so at first glance it would seem that vertical blending would be useful However our measurements do not sup port this premise THE MEASUREMENTS We modified a TDL model 414 Stereo Utility Amplifier to a low noise unity gain inverting amplifier with an audio bandwidth equal to or greater than the bandwidth of the 4010 We inserted it between Don s KAB Broadcast Standard turntable with a Stanton 500 cartridge and the left channel input on his 4010 The added inversion converts the blend control to vertical cut blending Don _ reports on the listening tests as follows T listened to a variety of vertical cut records from Edison Pathe Okeh and Rex played at 80 RPM I used a 3 5 mil elliptical stylus with the Edisons and an 8 mil spherical stylus with the oth ers I set the 4010 equalization controls to FLAT the rumble filter to BYPASS
97. he center channel for movie sound plus the envelopment and immersion that comes from adding the side and rear surround channels noting that in a home theater the lateral portion of the reflected sound especially from about 30 110 off axis left and right of the lis tener is more important for the sense of envelopment than a diffuse sound field reflected sounds from directly in front of or behind the listener con tribute little to a sense of spaciousness Toole went into extensive detail He described the variety of sources and lossy lossless codecs including upmix ing from two to multichannel playback Toole talked about various seating and speaker layouts plus the use of in surface speakers he does not rec ommend ceiling speakers even when tilted to aim the tweeters toward the listeners Architects make it diffi cult was his introduction to laying out a multichannel system in odd shaped multipurpose rooms The presentation turned to explaining various speaker designs from electro statics through horns modern horns don t honk they give us some control over where the sound goes they can play very loud with relatively less pow er and the low distortion and power compression allows for comfortable lis tening at very high sound levels Toole spoke about speaker imped ance which is anything but simple and the effect of speaker wire impedance ac knowledging that there is more to wire than it
98. he delta x ws is 0 03283V doing the same for the ik s the delta is 0 93946 10 4 BES ELA LAS tae WM ets ale ELA ATEN les Solving for the output resistance Ro 349Q for the cathode and x plate Ro This is the special case shown in the Radio Designers Z f Handbook 4th Edition RDHB4 page 330 eq 34a and is only Z Z valid when the total impedance of the cathode load equals the total impedance of the plate load resulting in a B of 0 5 Note that High End Components Made In Germany Since 1985 using the values of u rp RK and RP used for 1 above in equa x www mundorf com info mundorf com tion 34a results in a value of 338Q audioXpress December 2010 43 GENERAL CIRCUITS CO LTD QUALITY PCB amp SERVICE PROTOTYPE TO PRODUCTION instant online quote shopping cart ordering system China competitive prices free electrically test web http www pcbcart com E mail sales pcbcart com Tel 86 571 87013819 Fax 86 571 87036705 Add No 76 GuCui Road Hangzhou China WWW PCBCART COM FRONT PANELS _ amp FNCLOSURES bea N SUstomizedifrontipanels can be easily designedjwith OUP SOME was and production runs _ e Wide range of materia customization of pr _ material e Automatic orice calculation e Fabrication in 1 3 or 7 days Sample price 43 78 plus S amp H FRONT PANEL EXPRESS www frontpanelexpress com 206 768 0602 44 audioXpress 12 10
99. here is more useful and reli able information on the side of a tire than in most loudspeaker specifica tions This course is so extensive and thorough that attendees should be given an exam and earn college credits GROUND LOOPS Bill Whitlock s Jensen Transformers president Understanding Find ing amp Eliminating Ground Loops course is even better with his latest revisions and added content From his course handout A cable is a source of E3 audioXpress 12 10 potential trouble connecting two other sources of potential trouble This joke among electronic system engineers is worth keeping in mind Any signal ac cumulates noise as it flows through the equipment and cables in a system Once noise contaminates a signal it s essen tially impossible to remove it without altering or degrading the original sig nal For this reason no system can be quieter than its noisiest link Noise and interference must be prevented along the entire signal path Delivering a sig nal from one box to another may seem simple but when it comes to noise the signal interface is usually the dan ger zone not the equipment s internal signal processing From this concise in troduction Whitlock walked attendees through the ways and paths noise can take to get into a system He explained how to diagnose the source of each problem and how to prevent it As in all his classes he emphasized that bypassing the third wire gro
100. hich makes it easier to see whether the bar edges appear station ary It s a good idea to print on at least 67 pound stock or heavier because you want the disc to lie flat on your turntable You can easily trim your printed stroboscope to a round disc with a pair Of scissors but one problem remains ment accuracy The bundle is pictured in Photo 3 Because the light flashes at table speed One side of the disc is for 33 1 3 RPM and the other side cutting the spindle hole in the cen ter I solved this by building a spindle holecutter shown in Photo 5 Except for the inside diameter of the tubing the dimensions aren t critical I measured the spindle diameters of all my turntables and found they were all nearly 0 28 So I chose brass tubing with an inside diameter of 0 316 I sharpened the lower end of the tub ing with a file and it can be re sharp ened as needed I added the brass top cap soldered on to make it easier to hit with a mallet To cut the hole place your printed disc on a piece of smooth hard board or wood center the cutter over the printed hole and hit the cutter cap with your mallet i Wn III SS FIGURE 1 Sample printout from the free strobo exe program The large diameter makes it easier to see whether the bar edges appear stationary audioXpress December 2010 19 PHOTO 5 The center hole cutte
101. ich a road bump can transmit energy to the car body to resonant frequencies in other me u This is of course a tuned system with the mass of the system and the compliance of the coupler determining the resonant frequency That tuning must be such that it effectively decouples the counterbal decrease If either or both are decreased ance at the expected frequencies of record of various compliances The 701 arm was The benefit of the 701 arm design is its ability to work at lower resonant frequen ity to record warp and off center holes As a result when you work at the low end of the resonance range with this arm you will have better bass performance while retaining high immunity to warps as though the resonance were much higher teresting design The counterweight is _ isolated from the arm with a two stage flexible coupling As a result for steady The Ultra500 cartridge had ex state conditions such as playing a flat and perfectly centered record the full ity Quoted figures were 42cm sec at 400Hz 65cm sec at 1kHz 100cm sec back to the stylus compliance at 5kHz and 75cm sec at 10kHz all at x a tracking force of 1 2 grams Therefore Figure 2 shows the effect of the tone arm with and without the anti reso nance filter Cartridges with three dif ferent values of compliance are charted You can see that there is a reduction of the peak output at resonance
102. iegfried Linkwitz Douglas Self Nelson Pass Tom Nousaine A gt 2 r oy Ka eff wi eo att The foam damps lateral motion of the _ foam to keep the whole mass centered suspended mass which is essential be cause the center of mass is considerably x vertical movement but that s secondary vulnerable foam above the suspension points the bottom of the springs which makes it inher SUSPENSION SETUP Assuming you follow the same route with your suspended sub chassis that I did i e increase the suspended mass and stretch the stock springs to accommodate the heavier spring weight here are some tips you should heed It takes time to get everything settled but patience and a little foresight will be rewarded I assume you ll be doing a trial as sembly or two On your trials be sure to center the sub chassis over your holes cut out for the platter shaft and arm and avoid binding between the springs coils Centering entails attention to de tail Make sure your motorboard is level which will ensure your sub chassis is hanging as it will in use Also load down the sub chassis with the full weight Then make a note of what s off cen ter by how much and which springs you must bend Then do your bending reassemble and repeat as needed This can be a nuisance but getting the sub chassis centered up pays off especially centering the platter between the two motors I used a very light cable
103. ight arm As a result as the cam goes through its cycle ing of the arm are shown in Photos 16 ly and horizontally The other end of the actuating arm rests just above the bottom of the tonearm when viewed in the in the actuating arm is moved both vertical verted position as shown in Photo 15 The tonearm has a coupling pin that provides intermittent contact with the actuating arm When the actuating arm moves vertically it presses against the coupling pin raising the arm When it then moves horizontally it swings the arm over the record to the lead in grooves if it is in a start cycle or to the rest position if it is in a stop cycle The movement of the tonearm in the horizontal direction is the sole result of friction coupling of the pin with the flat surface of the actuating arm The broad flat surface of the actuating arm allows the horizontal coupling to the arm pin regardless of the arm position but de pends on the proper friction coupling In the case of my turntable over 30 years of activity were enough to wear the surface of the pin sufficiently to prevent that friction coupling from occurring properly To fix the problem I first cleaned and then lubricated the actuating arm and tonearm coupling pin Then I adjusted the vertical movement of the actuating arm using the screw shown in the center a Fs PHOTO 13 Cam level actuator of Photo
104. ightly so the shaft turns freely You can do this by burnish ing using a smooth metal rod or you can abrade it open using newspaper wrapped around a round pencil The bearing metal will rub off on the paper just like solder or any other soft alloy would This is an iterative process i e squeeze then burnish again and again until you re satisified the shaft is con tacting a thin ring of metal right at the top of the bearing well It should be close but not binding Fig 1 Now you have a bearing consisting of around nub resting in a dent on the bot tom and a thin ring of contact at the top and nothing in between The only task left is to polish the nub My method here was perhaps crude but it served Using a da is eliminating play at the top of the bearing sleeve To accomplish this I used a ball bearing to press down the 1 8 bit I drilled a very shallow hole nothing more than a dimple really in the end grain of a small block of hard wood On top of that I layered a small square of roofing felt or tar paper then some 300 grit wet or dry paper Then I wrapped three or four turns of masking tape around the inner platter s record spindle chucked it in the drill press and wet the abrasive paper with some water Next I lowered the nub into the dimpled paper turned on the press at x very low about 120 RPM or so revs and settled in for the long ha
105. ils are visible That s a record weight on the left rear 28 audioXpress 12 10 www audioXpress com ii x project is all about screwing around with the AR turntable until it s transmogri fied into something beyond recognition Hence the title Wretched Excess This began innocently as most silly _ things do and grew like topsy Photo 1 I wound up with a table with a moder ately heavier platter but lots of damping a table with a low contact low clearance bearing with a belt drive system that doesnt impose bias lateral force on the bearing And a suspension system tuned a full half octave lower than the stock XA which is simple really same springs twice as heavy I also designed it so that the sub chassis bounces in uni son or reasonably close which wasn t difficult You just need to ensure that each spring sees the same load This wont be a set of instructions so you can replicate this beast I ll provide the photos and occasional figure and describe what it is I ve cobbled together and why If you want to build your own and have a reasonable set of tools and mechanical chops you re all set You ll probably want to make changes here and there according to your own lights or cherished crackpot theories about tables to which I say Have at it PHOTO 3 The splinted sub chassis with stretched suspension springs and the inner pla
106. in Application Note 1999 Sine Wave Generator is Crystal Accurate Maxim has published 1 3 The application note states that sine waves are generated by filtering a square wave A square waveform is composed of odd harmonics Filtering out the odd harmonics leaves a sine wave composed of the fundamental wave The IC filter selected requires a clock frequency at least 100 times the desired frequency Rather than use a separate crystal os cillator and divider network I chose to use a single resistor setpoint type of oscil lator part number LT C17994 manufac tured by Linear Technology www linear com You may consider other options such as using a programmable micro controller or similar logic based device I chose a dual binary counter based on the design in Maxims application note The dual binary counter divides the input square wave by 256 This pro the 100x requirement of the filter Be cause the desired output frequency is 60Hz the equation for calculating the i prior to inserting soldering into the cir cuit If you use a 1 tolerance resistor the value of the setpoint resistor should be okay but if you design for the tighter frequency adjustment span the value may be too large and you may not be x able to achieve 60Hz desired oscillator frequency is FOSC 60Hz x 256 15 360Hz 1 Next I used the equation for selecting the resistor to set the
107. ipment 800 321 2834 x 50W Gainclone modules from US45 ch includes PSU Great sound www designbuildlisten com Mouser Electronics Mundorf EB GmbH OPPO Digtal INe n n 5 41 Parts Connexion Parts Express Inti lin nn n CV4 PCBCart com SB Acoustics SOLE MAN Gites n 11 SRS Stanford Research Systems Tang Band Industries Co Ltd 46 The Last Factory The Tube Store Ing ie 45 Wavecor CLASSIFIEDS All Electronics Audio Classics Lid eee 35 Design Build Listen Ltd 35 amateur incorporated THE 2010 LOUDSPEAKER INDUSTRY SOURCEBOOK is available on line by subscription Audio Amateur Inc Phone 603 924 9464 Fax 603 924 9467 custserv audioxpress com ws here qudiob I SUBSCRIBE TO THE NEW AUDIOBYTZ E NEWSLETTER and stay up to date on everything audio From new technology to product announcements to solutions for everything to do with sound editor David Ranada will keep you informed in this biweekly free email To start your free subscription simply visit our website at and provide your email address Audio Amateur Inc udio Toll free 888 924 9465 amateur incorporated Phone 603 924 9464 Fax 603 924 9467 SUBSCRIBE AND SAVE _TUBES VS TRANSISTORS A CALL FOR MORE TESTING Building A True RMS Voltmeter SAVE NEARLY 50 OFF THE COVER PRICE Call 888 924 9465 or subscribe on line at www audioXpress com audioXpress Dec
108. is table if you draw a line from the midpoint between the two platter end springs and the one out by the tone arm you ll see it s 297mm long You want the two springs on the platter end to shoulder two thirds of the weight so it follows that the center of grav ity should be 99mm one third away from the midpoint I mentioned which puts it 62mm away from the platter and 231mm away from the tonearm pivot Concerning the springs perhaps more discussion is in order Galo and presumably others go in for stiffer springs to cope with a more massive suspended sub chassis I demur What s the point of a heavier suspended mass if youre going to give away the result ing lower resonant frequency by stiffen ing the springs I opted for the stock springs I just stretched them out some to cope with the more massive suspend x ed structure Here s how The stock XA suspend ed mass is about 2 3kg 5 Ib Uncom pressed the springs are about 42mm long compressed they measure about 22mm That s a deflection of 20mm per 765gm one third of 2300gm I wound up with a modified suspended struc ture of about 5 1kg 2 7kg more than the stocker If I want to wind up with a com pressed spring about the same length as a stock XA I need about 25mm more spring So I stretched each spring out to 67mm that s 42mm 25mm which compresses
109. it would be accepted yet Nortek chose to close the company rather than take the deal that was on the table From Imerge s point of view the order books were full the product lineup was stronger than ever and there were many more exciting in novations to come through 2010 The issues that have led to this sad state of affairs belong to Nortek not Imerge the MBO would have put Imerge s des tiny into its own hands but it was not to be It really is such a waste Of course Nortek may still decide to sell Imerge s assets at a later date Personally wonder whether Nortek s lawyers worried about what the music and movie companies might do about the ripping function on which Imerge s business model was based aX CONTRIBUTORS David J Weinberg Tobias Audio Silver Spring Maryland 301 593 3230 Weinberg DJ BostonAudioSociety org is an engineering consultant and technology journalist on audio video and film technology He provides audio and home theater engineering consultation and professional on location digital audio re cording services to companies radio stations and individuals He brings to his work an MSEE a First Class Radiotelephone license and over 40 years of continued study and active involvement in the audio video and computer industries He is Chair of the Audio Engineering Society s DC section and a mem ber of the Society of Motion Picture and Tele vision Engineers DC section Wein
110. l result in longer battery life The two high efficiency LEDS on the PCB L1 and L2 in Fig 1 serve as battery moni tors Normally L1 will light briefly for about 1 second after the amp has been switched on charging time of C14 When the supply voltage drops below 6 8V the LED will re main on continuously A permanently lit L 1 indicates that the E block should be replaced In my opinion it is wise to replace the bat tery a little earlier My ears tell me that with a new 9V battery the K272A sounds better than with a battery whose voltage has dropped be low 7 5V At low battery voltages thus at low anode voltage of the valves the 6418 stage may become overloaded in heavily modulated passages resulting in audible distortion A fel low audiophile from Malaysia runs his K272A from a 12V car battery and claims excellent results with such an overkill power supply If the AA batteries are in good condition LED L2 will be shining brightly Thus L2 serves aS a power on Indicator When the battery voltage approaches 2 0V the LED will extinguish Even when L2 is dimly lit the fila ment voltage is still at an acceptable value You should then replace the AA batteries soon Fourth because there is no resistor run ning from the negative pole of C7 and C8 to ground the amp produces a minor tran sient during switch on and a rather strong transient click in the headphones during switch off It will not damage either your
111. l will be unequal The test band mentation if you have a mono switch on your preamplifier I do not but I do have fectively adds the signals from both traces and displays the sum of those two When I used that function the resulting signal was a null indicating both channels were in balance and the azimuth was correct which is good because there is no easy way to change that parameter in this tonearm After all the adjustments were com oe My FIGURE 2 Vertical tonearm resonance plete I ran tests for tracking ability The Hi Fi LP has three bands numbers 1 4 x and 8 on the second side to test track ing All three contain a 300Hz signal re corded at 15dB Their positions across changes with distance from the outside of the disk to the inside ceptionally high stated tracking abil given those specifications I was not sur prised that the test yielded no mistrack ing on any of the bands The last test was for cartridge tonearm x resonance The test LP has two bands numbers 2 and 3 on the second side that test for the resonant frequency in the horizontal and vertical modes respective ly Each contains a low frequency sweep and a 1kHz pilot tone for audible confir mation of the resonant frequency Tonearm cartridge combinations have a resonant frequency that depends on the mass of the assembly and the com pliance of the cartridge This is similar chanical devices such a
112. le for driving the VPI motor I went to my parts bin and pulled out a few components that were used to develop x justing the turntable motor s rotational speed however the VPI motor does not u the 1311 A rebuild and assembled them on a prototype experimenter s board My calculations showed I needed to design a circuit that would meet the motors power _ requirements 11W and allow for over x head The LM386 power amplifier I used in the 1311 A was satisfactory to prove used the same circuit I previously de veloped for the 1311 A oscillator This the concept however in deference to sup need a more powerful amplifier www audioxXpress com sine waves from square waves I found an AC inverter manufactured by Radio Shack www RadioShack com which provided a suitable enclosure containing aluminum heatsinking case electrical outlets fused inputs on off switch and so on This formed a basis for the VFSMC I could build a circuit board substitute a new transformer and wire it back up to the existing 120V AC outlets I only needed to modify the en closure for my application Photo 1 CIRCUIT DESCRIPTION AND OPERATION circuit which has proven to be very ro erating a sine wave output is based on x an article by Maxim IC for their single chip 8th order low power Bessel and Butterworth switched capacitor filters The article is contained
113. le value The JKP Affinity models are known for accuracy of color rendering over the entire gray scale range black to white excellent uniformity of color and brightness ver sus viewing angle neither color shift s w k r i r P a g L E EF E F L i k m i m a a W s r m a r p Pa 3 p iy a a a PHOTO 4 NanoLumens s 112 flexible display WW WW A December 2010 E9 audioXpress nor visible hot spotting plus freedom from video image noise usually caused by interaction between the pixelated projected image and screen graininess Sharp www SharpUSA com boast ed of the added yellow primary in its Aquos Quattron models Photo 5 which support 3D viewing with active shutter glasses two come with each dis play additional glasses sell for 200srp that can allow one user to watch the 3D video while the other watches the same program in 2D The yellow primary might expand the color palette for pho tos and PowerPoint presentations but it is not correct for video which is strictly based on specific red green and blue primary colors Sharp also boasted that the LED backlighting technique used in these models delivers 1 8x the light output of traditional LED backlight ing this is less than one f stop and will only partially offset the light output lost when viewing 3D Sharp also released a 3D ready DLP projector as
114. led wheel shown on the left side of Photo 1 Removing the two will allow the hinge assembly to be re moved Repeat for the other side as well can disassemble the hinges as shown in the lithium grease Reassemble the hing need to readjust the hinge tension by trial and error after attaching the dust cover PHOTO 16 Manual arm lift lever 14 audioXpress 12 10 THE STROBOSCOPE The final repair was to replace the bad neon lamp in the stroboscope section The original lamp was a special design as shown in Photo 20 At the time I searched the web for a replacement there were very few left and they were Phillips screws and the retaining plates expensive At first I thought about de might also add noise in the low level en vironment of the signal circuit es and install them in the base You will Instead I decided to see whether the PHOTO 17 Manual arm lift lev www audioxXpress com parts bins but would need to deal with the fact that the wire leads were quite different from the flat contacts of the standard lamp Access to the stroboscope lamp is from the top section under the platter A small black housing holds the lamp The cover of the housing has the prismatic lenses signing a circuit that would drive an _LED synced to the line as a replace Once the hinges are out of the base remove the knurled wheels and pull the hinge pins out of the assembly Th
115. leson com audioXpress December 2010 23 CLOCK Generation Ui Le _ J a E uF S FREG DJUST SFRONT PAREL NP GROUND __f H square to Sinewave Conversion 44 Hz AC Motor Transformer Driver WRI 2 AAPL ADT C5 H Cur TOAT ASS SINEWRVE OUT ree Ts LOH CLOCK G J LILI External DC Yoltage ua LPeasi w4 FDBK Y GHD ERROR 6BHz 1 VAC Output to AC SYNC Motor Low Voltage Power Supply former is rated at 15 volt amps which provides a design margin of more than 25 with respect to the motors maxi mum rated power Primary windings are 115V AC and the secondary windings are set for 7 to 8 9V AC depending x upon the load The datasheet for this transformer is found at reference 8 BUILD AND OPERATIONAL MEASUREMENTS I designed built and tested an initial prototype circuit board Photo 2 Except for an error in the PCB layout the de sign worked as planned when assembled x outside the Radio Shack AC Inverter enclosure I noted no other problems I used two potentiometers to fine tune the circuit s final resistor values The Hurst turntable motor operated perfectly over a frequency span of 53 to 68Hz I did encounter a minor glitch when I J connected the output of the TDA7396 to a 10kQ load rather than a transform er The TDA7396 s protection circuitry had kicked in and placed the amplifier
116. m raised and positioned itself over the lead in groove and the arm gently descended to the record Yes Success I then looked at the stroboscope window tridge housing with the cartridge reat screws and tonearm lock I rechecked and placed an LP on the platter The FREE SAMPLE IF YOU BUY SELL OR COLLECT OLD RADIOS YOU NEED moment of truth was at hand I activated the automatic cycle and saw a bright clear pattern Photo 23 All was well for the repair phase of ANTIQUE RADIO CLASSIFIED Antique Radio s Largest Monthly Magazine 68 Page Issues Classifieds Ads for Parts amp Services Articles Auction Prices Meet amp Flea Market Info Also Early TV Art Deco Audio Ham Equip Books Telegraph 40 s amp 50 s Radios amp More Free 20 word ad each month for subscribers Subscriptions 24 for 6 month trial 45 for 1 year 60 for 1st Class Mail Call or write for foreign rates The Collector s Guide to Antique Radios 7th Edition by John Slusser amp Radio Daze 10 000 prices 1 200 color photos 24 95 Payment required with order Free shipping In Mass add 5 tax A R C P O Box 802 A16 Carlisle MA 01741 Toll free 866 371 0512 Fax 978 371 7129 Web www antiqueradio com E mail ARC antiqueradio com audioXpress December 2010 15 PHOTO 21 New neon position ADJUSTMENTS To get the maximum benefit of a tune up 3 you need a good test record
117. mbers BC1616 and BC1879 They have work ing voltages of 275V and 630V respec tively and although both have nearly doubled in price since I purchased them they are currently still relatively inexpen x sive at 0 82 and 1 17 Figure 1 shows another capacitor in that section of the power supply that I used to drive the neon lamp in the strobe section Because I would already This section of the power supply is located in a small metal box on the un derside of the chassis Photo 5 To access the components inside I removed the two small retaining screws that are lo cated at each end of the case and lifted up the cover The two capacitors were now clearly visible Photo 8 Because there are no component labels on the board I took note of the values marked on the capaci tors to determine their identities Access to the bottom side of the board requires that you remove it from the box To do this I first needed to re move seven leads two mains leads two neon lamp leads and three transformer leads You can unsolder the mains and neon leads from the lugs on the board and unsolder the transformer leads from the lugs directly on the transformer As always I made sure to record the con nection sequence of the leads before re moving them One end of the board is held in place by metal tabs punched through a slot in the box Once the cover was off I moved one side of the
118. n Heiss s New Technologies Up date complemented the Pre Game show For over the air DTV Heiss has found that the Philips PHDTV1 Silver Sensor indoor antenna about 80 at www Amazon com designed for UHF 14 51 works well However DTV is not avail channel reception channels able everywhere in the US because thousands of low power analog trans mitters are still on the air How soon they will be required to convert to digi tal transmission is not yet Known 3D will likely come to the home at some point but there are questions about how many consumers will soon replace their recently bought HDTVs with one that displays 3D content and how many people will choose to buy and wear 3D glasses for long stretch es of viewing time There will be little 3D content available to consumers for quite a while Sports is in the lead in creating 3D content for home viewing Sony issued a disclaimer that if you update your Playstation 3 with the firmware version that supports 3D the Blu ray audio will only play back as Dolby Digital or DTS lossy encoded 2 0 or 5 1 channel formats Dolby True HD and DTS HD Master Audio soundtracks will not play back Sony has not explained why this is so but speculation is that the Playstation 3 s processing power is insufficient to si multaneously support 3D video and high resolution audio playback Video distribution is migrating from disc and hard disk drive based systems toward streaming
119. n There are 3D kits for computers that include a 3D video card software an emitter to control the 3D glasses and a pair of active shutter 3D glasses The monitor must have at least 1680 x 1050 or 1920 x 1080 resolution and sup port a refresh rate of at least 120Hz Between alternating the presenta tion of an image to each eye and the inherent light attenuation of the 3D glasses the 3D image is much darker than conventional 2D images requiring much brighter displays that must auto matically lower their light output when switched back to 2D viewing There are two types of polarized passive 3D glasses horizontal verti cal head tilting will cause image cross talk and circular one eye glass clock wise polarized the other eye glass counterclockwise polarized head tilt ing will not cause crosstalk If you can use passive 3D glasses www Ameri canPaperOptics com has low prices MicroVision Optical www MVO3D com offers more stylish passive 3D glasses Three not showed autostereoscopic no glasses needed displays at the IFA Berlin 2010 consumer electronics trade show vendors specified www I IFA Berlin com but the view ing angle was rather limited and it will be years before commercially practi cal large screen autostereoscopic 3D displays will become available Toshiba exhibited an autostereoscopic panel display at CEATAC in Tokyo in early October 2010 DISPLAY CALIBRATION Joel Silver s Imaging
120. n what found interest ing at CEDIA Expo 2010 but there was much more that would likely have in terested others CEDIA Expo will be in Indianapolis September 7 11 2011 FII be there How about you aX audioXpress December 2010 E11 Try Try Again By Barry Fox n 1982 right at the end of the eo age of vinyl Teldec the company jointly owned by Tele funken and Decca experimented with a completely different way of cutting hi fi LPs called Direct Metal Master ing DMM This had spun off from the work done by Teldec at a semi secret lab in North London run by Decca s respected recording engineer Tony Griffiths on TeD a floppy video disc The TeD video disc had a super fine hill and dale groove cut in a flimsy plastic disc about the size of an EP The disc spun at 1500 rpm and played ten minutes of color video when tracked by a mechanical sled shaped stylus Panasonic killed TeD with Visc a rigid 12 LP that worked in much the same way as TeD to deliver an hour of color video from each side of the disc Visc was mind bogglingly clever but was soon killed by JVC s VHD which used a grooveless con ductive plastics disc tracked by a capaci tive stylus and by RCA s CED Selectavi sion which used a grooved capacitance disc Both came to market but were soon killed by Philips Laservision Laserdisc the optical video disc that later spawned CD DVD and Blu ray But when TeD died Teldec adapted the vide
121. neral wool or open cell acoustic foam Rigid boards become somewhat reflective at high frequencies and at grazing angles Absorption and diffusion are ben eficial if applied to the right problem and located correctly Vertically ori ented hemicylindrical or triangular shapes stretched floor to ceiling will scatter sound down to 200Hz if they are about 12 deep Toole cautioned to leave space between adjacent pan els for maximum effect Irregularities along the walls are beneficial Acoustic research has shown that lateral reflections are important for a pleasant spatial sensation In home the aters some of these sounds come from the side and rear channel speakers Toole emphasized that the loud speaker and room it is in are a system and interactions must be recognized and issues addressed At low frequen cies the power response of a speaker is most representative of what we hear while at high frequencies the speaker s on axis frequency response is its most important characteristic assuming it is aimed at the listener Over the range from several hundred Hz to several kHz the bandwidth providing timbral identity for voices and musical instru ments both characteristics affect the perceived sound He discussed room modes acknowl edging that with stud and drywall construction the room mode effect isn t as severe as theory predicts He also stated that there is no ideal set of room dimensions because room
122. nics decided to use bat teries alkaline cells for feeding the K272A The 6418 heaters are fed from two AA type batteries The valve anodes and output buf fer receive power from a small 9V battery The buffer chip is a PT2308 made by Princeton Technology Corporation www princeton com tw a company from Taiwan It is functionally compatible to the TDA1308 and also has the same pin out Because it cannot operate at voltages greater than 5 5V a low drop series regulator IC2 pro vides a clean 5V supply to IC 1 The valve heaters are fed by a one transis tor circuit D1 D2 and LED L2 receive 2mA current from the 9V supply via resistor RY They provide a reference voltage to transistor Q1 which supplies 2 4V 10mA to the series connected valve heaters Transistor Q1 is only turned on when the 9V supply is present Thus you can turn the entire amplifier on and off with a single switch in the 9V supply rail LED L1 serves as a battery voltage monitor see below DESIGN CRITIQUE The K272A circuit raised a few doubts in my mind Note that am a home constructor not an EE and my experience with tube technol ogy Is limited Don t shoot the biologist 1 The series configuration of the valve heaters seems a bit odd Because the 6418 is directly heated heater potential determines cathode bias voltage V2 will always run at higher bias voltage and lower anode current than V1 and the voltage gains provided by V 1 and V2 will b
123. nson curves Such playback calibra tion in the studio and in the home will help the consumer hear the same tonal balance as created in the studio Part two of his course covered mul tichannel sound and system configu rations with a section on amplifiers and speaker characteristics In Toole s words at its conclusion participants should be able to express in general terms the requirements for a sur round sound system optimized for a given room and audience size summa rize the requirements for specific loud speakers to deliver good sound and the appropriate directional and spatial illu sions of multichannel music and mov ies distinguish between those specifica tions that are important and those that are not informative and decide on the key elements of a home theater system such as loudspeakers amplifiers wir ing based on an analysis of the custom er s needs and the restrictions imposed by the realities of the room Toole broke down the basic dimen sions of listening into sound quality timbre bandwidth spectral balance dynamic range freedom from distor tion localization horizontal vertical and distance including phantom sourc es for all listeners and spatial dimen sions apparent source width ASW listener envelopment LEV and im mersion He discussed the similarities and differences between what we want in home theaters versus concert halls He emphasized the importance of t
124. nt capacitor ever made oudience OEM amp dealer inquiries invited Call 800 565 4390 www audience av com audioXpress December 2010 37 sons and always got the same results I checked the Stanton s channel balance with the 8 mil spherical stylus and it was nearly perfect so that s why the wide groove verticals didnt show the best blend effect at one oclock I did not think that the Stanton car tridge was as unbalanced as it appeared to be in Fig 3 I tried some other styli with interesting results A 3 7 mil truncated elliptical stylus from ExpertStylus in the UK on a genuine Stanton cantile ver and housing had excellent channel balance and sounded great with the Edisons I also discovered that what I thought as a genuine Stanton 78 stylus x was a counterfeit and had poor channel balance and a 6dB lower output than my two genuine Stanton styli both of which had very good to excellent channel balance Overall I found no sup port for the use of a verti cal blend control other than to compensate for cartridge stylus channel imbalances My listening tests suggest that vertical recordings es pecially the narrow groove Edisons are more sensitive to these stereo cartridge im balances than lateral record ings I think that anyone who is doing restoration of vertical recordings should ensure accurate channel bal ance before converting the signal to mono DISCUSSION Because th
125. nt circumstances will favor the use of Comparing the plate voltage and current with those of 1 above the delta ep is 0 84358V and the delta ip is 0 03995 10 i then the plate Ro 211159Q This approxi mates the results of equation 30 page 330 i of the RDHB4 which applies when only the plate output impedance is under test Note that in this case B is no longer 0 5 and i the plate circuit acts as though the feedback i was a current feedback When using the val ues used in 1 above equation 30 results in i a value of 190000Q for the plate Ro Repeating the above for changes in RK only by setting RK to 9000Q and leaving RP at 10000Q results in a value of 846Q for the cathode output imped ance Equation 31 on page 330 of the RDHB4 results in 843Q either the AM or N amp FA as the user sees fit Recall that a general definition of the impedance between two points in a circuit is the voltage change across those points caused by a test current flowing through them divided by that test current This is in accord with Mr Morton s e1 e2 i1 i2 He creates a test current in a circuit with voltages already present by combining 90K i loads with 10K Rps and Rks to make 9K But the 11 12 change in test current he uses is not that through the 9OK load re sistor but rather the change in total triode current This means that the impedances he calculates are those looking into the
126. nt two rubber grommets on each 6418 to damp resonances Photo 2 Do this before you solder the tubes on the PCB not afterward Although the grommets are effective this treatment is only partially suc cessful Touching the PCB or hitting the table on which it stands results in a high whistling sound which persists for more than 30 seconds Ap parently this peculiar form of microphony is typi cal for subminiature hearing aid valves have encountered it in DIY projects of my own which used German Telefunken 56 72 American Raytheon 6088 6418 and Russian 1SH18B 1SH24B 1SH29B 1SH37B subminis In order to reduce microphony further you could mount the PCB and tube assembly on springs or Suspended in soft plastic foam Also you could internally damp the cabinet with bi tumen pads If the board is securely mounted well screened and not touched the amp is dead quiet and does not produce any audible hum or noise in the absence of a music signal Second the K2 2A is susceptible to hum induction when the valves are out in the open or the PCB is placed in a wooden cabi net During initial listening tests involving the bare PCB on my desk close to two comput ers had to carefully orient wires in order to avoid interference Small movements of a wire could transform a quiet amp into a hum ming bastard and vice versa Thus decided to mount the amp in a plastic cabinet internally covered with copper foil connecte
127. o disc cutting system to audio mastering The object of DMM was to eliminate the perennial problems with master lacquers such as faulty blanks and blemishes caused by the first stages of electroplating With DMM a diamond stylus cuts the groove directly into an amorphous copper metal coat ing on a blank stainless steel disc There is no memory effect relaxation of the E12 audioXpress 12 10 plastic with high frequency loss and the first stage of electroplating is taken out of the process which reduces the risk of plating errors DMM also made it possible to pack grooves tighter thereby increasing playing time by 15 The heads which cut soft lacquer need several hundred watts of driv ing power so you can imagine what it takes to cut copper metal Teldec used a modified Neumann stereo cut ting head and to help the stylus cut through the metal superimposed an ultrasonic signal of around 70kHz on the audio signal being recorded This acted in much the same way as the bias in a tape recorder which shakes up the magnetic particles The bias signal used for the DMM process mechanically ex cited the diamond cutting stylus In July 1982 Teldec offered to license the system to any record company for a one off fee Between 1982 and 1986 Melodiya Virgin and PR records each signed to use the system By 1985 the hi fi press was already worrying that the high frequency bias might cause audible beat effects There was t
128. oXpress 12 10 especially because so many products require live Internet access Naturally 3D will be everywhere but there are still questions about when 99 how and where There are some universal 3D glasses but each of the 3D technologies suffers from problems that can confuse the 3D glasses such as crossed sequencing each image to the wrong eye or image crosstalk when tilting your head to the side There is no source for 4k 4096 x 2160 con tent to reach the consumer HDMI is changing how they iden tify capabilities see HDMI Hot Seat below Look for the feature list not the version ID You need HDMI 1 4a compliance for 3D but only for send ing control data to the display the metadata not for the 3D video data Also every device in the HDMI chain must support the features required for a function or it probably will not work Be aware that some of the HDMI ex tenders on the market employ lossy video compression degrading video image quality HDMI v1 4a added the ability to send 3D video control signals to tell the display the 3D video frame format and to control display and 3D glasses switching some 3D signaling might work on HDMlv1 3 compliant devices but it is not guaranteed an optional audio return channel ARC sends the audio from the display back to an A V receiver or audio processor an op tional HDMI Ethernet channel optional features for automotive and portable
129. onal material to reproduce sound For example the use of real wood as a cone material gives you very natural and worm sound the use of Bamboo which is very light and strong which translate in very fast reacting driver and the use of Carbon Fiber which is extremely light and strong gives you a very analytic and very detailed sound 12cm Midrange Wood Cone 88db HR124B8 10L 31 62 15cm MidBass Wood Cone 86db FR148B6 11L 59 84 Wood Cone 85db 59 84 FR148B6 17L Bamboo Cone 87db FR148B6 18L 45 90 Carbon Fiber 87db FR148B8 10M 59 50 17cm MidBass Wood Cone 89db FR173B6 16L 79 90 Carbon Fiber 90db FR173B8 10M 79 90 e 2 audioXpress December 2010 11 SOLEN lectronique Inc 4470 Av Thibault St Hubert QC J3Y 7T9 Canada Tel 450 656 2759 Fax 450 443 4949 Email solen solen ca http Awww solen ca 4 pw l L r I T PHOTO 8 B in doing this job showing two exploded parts views with a photo of the bottom mechanism and callouts for each point of lubrication indicating the type of lu bricant to use Photo 9 The service manual called for three brands of lubricants that are no longer generally available a high performance oil a silicon lubricant and a high per formance lithium based grease I had on x hand modern replacements for all three x For the oil I used Mobil 1 for the silicon lubricant I used CRC heavy duty silicone and for the
130. opes have probably been around since the first turntables were produced that is over 100 years How _ ever the earliest one I have has a copy right date of 1934 It was printed and given away by the Universal Micro phone Company Inglewood Calif It contains four bands 78 RPM 25 or 50Hz 78 RPM 60Hz 33 1 3 RPM 25 or 50Hz and 33 1 3 RPM 60Hz The disc came in a cardboard folder and is shown on the left side of Photo 1 power mains frequency 50 or 60Hz OTHER COMMERCIAL STROBOSCOPES _ boscope disc appears to be stationary _when the turntable speed matches the _ speed printed on the stroboscope A _ stroboscope does not work with direct nating current AC lighting because the light flashes depending on the Esoteric Sound sells a 12 band strobo scope covering 16 67 to 90 RPM for 60H72 This disc is also shown in Photo 1 Pm not sure where the other disc in the photo came from because it has no company name It is for 78 and 80 RPM at 60Hz KAB ElectroAcoustics offers a turntable speed tester the KAB SpeedStrobe It consists of a stro x boscope printed on a 10 diameter 20 mil thick PVC disc with a quartz crystal controlled illuminator 60Hz that is said to be 99 99 accurate The illuminator is battery powered so you can use it anywhere The strobe disc is unique because instead of bars it has the rotational speed printed as number
131. pre cious ears or cans but it Is slightly annoying Fifth the K272A can drive sensitive head phones nicely but it is less sulted for power hungry cans The Grado SR 125 329 98dB mW and Sennheiser HD465 60 worked well but a third headphone which tried an orthodynamic Yamaha HP1 150 93dB mW performed suboptimally Although ad equate volumes could be reached the amp worked close to its limits and it sounded rath er strained In contrast to the Grado SR125 the Yamaha HP1 performed better on the Stor amp than on the Oatley product Maximal bandwidth of the amplifier is 1OHz to 5OkHz 3dB The square wave re sponse looks nice with no signs of instability or visible ringing some tilting at low frequen cies because of the capacitor coupling and some rounding of the edges at high frequen cies 1OkHz or greater Voltage gain is 7 in put controls turned fully clockwise and the output is limited to 3V peak to peak With Grado and Sennheiser phones very high vol ume levels are possible higher than my ears will tolerate Oatley Electronics writes This low cost tube preamplifier lets you experience tube sound They could also have written great sound For the asking price of 30 Australian dollars the K2 72A is an absolute bargain And it does not involve any dangerous volt ages But switch off your mobile phones or move to the Australian desert Notes 1 Mark Houston s review of a pre
132. procedure each time you But immersion in a spreadsheet still leaves sons for this First Ro is a TCZ not an EZ Sec ond Ro can be shown by derivation to be ex actly half the TCZ from plate to cathode This i should not be a surprise since RDHB4 does not claim that Ro is the impedance between the plate and cathode Third the voltage term in the N amp FA Zpk should actually be delta_e x ep1 ek1 ep2 ek2 the change in voltage between the plate and cathode And for that expression to work properly Ap in the spreadsheet would need to be changed to the negative of what was given to reflect the fact that ek and ep are in fact negatives of one another in a balanced cathodyne For a choice of ik1 ik2 ip1 ip2 for x i1 i2 the result of this Zpk EZ calculation equals 2rp u 2 If the change in test load current O ep2 ek2 2 x 90K were cho x sen instead the TCZ result Zpk across the plate and cathode would be in accord with x 2rp 2 u Rk Rp as long as Rk Rp strongly urge anyone employing N8FA to use a spreadsheet to avoid the accumulation x of numerical errors that occur with the trunca tions of intermediate results that are so tempt ing with hand calculations If one is not avail x able you should at least retain all intermediate calculations to a good degree of precision Finally measuring Impedances by con x necting a load works
133. r MAX7480 filter is run through a 50kQ can achieve a tighter frequency adjust The two logic outputs Fig 1 are taken from the counter HIGH CLOCK and LOW CLOCK The In reviewing the application notes Fig quency of the MAX7480 8th order _ low pass Butterworth Switched Ca i pacitor Filter and the second stage bi nary counter D output sets the LOW CLOCK output frequency of the MAX7480 filter and is the frequency the VFSMC s AC output is set to HIGH CLOCK sets the corner fre The Dual Binary Counter sheet is at reference 6 The MAX7480 datasheet shows the input signal to the MAX7480 within its with very low harmonic distortion and does not have the noise content that the truncated or modified sine wave type DC AC inverters have Finally the sine wave output of the potentiometer with the wiper AC cou pled to the output power amplifier s in verting input via capacitor C5 I looked at several output amplifiers before finally settling on a bridge type audio amplifier TDA7396 The attrac tive feature about this amplifier is that it is a self contained bridge type of am plifier operating off a single voltage sup ply capable of driving low impedance loads like a transformer This keeps the x parts count down and makes the circuit _ easier to troubleshoot You can drive the TDA73965 pair of output
134. r which I built from a piece of brass tubing with a piece of 34 diameter brass rod for the mallet cap STROBOSCOPE LAMPS Incandescent lamps ordinary light bulbs with a filament work but not too well The filament does not cool erating on AC power work well be cause both produce pulses of light even _ This lamp operates from a 12V AC x wall transformer and the bars are very much between cycles of the AC power so the light output is rather constant Fluorescent lamps are about the same The phosphor coating on x the inside of the tube continues to radiate light between the AC power ful unless the room is dark Better lamps cycles You can see the stationary PHOTO 7A The DIY multiple LED stroboscope lamp The 14 LED array is epoxied to the inside of the PacTec en closure The four rubber feet included with the enclosure ensure the LEDs do not touch the tabletop 20 audioXpress 12 10 appearing bars but their edges look fuzzy so it s difficult to set the speed lamp Photos 7A and 7B A circuit x diagram with parts lists follows in Fig 2 As you can see the circuit is simple right on Neon lamps and white LEDs op though your eyes cant really see the pulses at least not with 60Hz power You can use a neon nightlight Photo cent light The cost of the parts was under 20 6 but it s rather dim so it s not too use PHOTO 6 An ordinary
135. rough NH 03458 0876 Periodicals postage paid at Peterborough NH and additional mailing offices POSTMASTER Send address changes to audioXpress PO Box 8 6 Peterborough NH 03458 0876 CLASSIFIEDS amp WEB LISTINGS Contact Janet Hensel Advertising Department audioXpress PO Box 876 Peterborough NH 03458 603 924 7292 FAX 603 924 9467 E mail janet audioXpress com Printed in the USA Copyright 2010 by Audio Amateur Corporation All rights reserved TM Satori oy SACOUSTICS Introducing the SATORI line Satori isa Buddhist term for enlightenment The word literally means understanding Satori translates as a flash of sudden awareness or individual enlightenment and while satori is from the Zen Buddhist tradition enlightenment can be simultaneously considered the first step or embarkation toward nirvana ri 6 Midwoofer Just a few features e Egyptian Papyrus cone epc e Fully optimized Neodymium magnet system Low FS e Customizable for OEM use Salt MW16P satori 29mm Ring Radiator TW29R Just a few features e Fully optimized magnet systems e Cast housings e Customizable for OEM use e Patended We have spent a lot of time trimming the fine details of these magnificent drive units and we are certain you will achieve Specs Specs ming 4 sonan s 590 Hz Nominal Impedance 8 Q Free air resonance Fs 29 Hz Nominal Impedance 02 Free air resonan
136. s are not perfectly rectangular and not all types of room modes are equally au dible due to construction differences Multiple speakers such as in a stereo or multichannel system tend to at tenuate the overall severity of room mode effects although there likely will be differences in the sound from each speaker Toole showed that in a room with the listener centrally located and speakers placed in compliance with the ITU R BS 775 circular layout there will be three different bass responses one from the center channel one from the left and right channels and another from the left surround and _ right sur round channels thus the sound varies as its location is panned Toole explained why he recommends using multiple subwoofers and that his research has shown the simplest place ment is in the four corners to improve the uniformity of bass for multiple listeners He described blind listening tests of speakers in small rooms and that while people like different sound they tend to like the same speakers in well designed and run blind listening tests preferring those that have a relatively flat on axis frequency response plus 30 and 60 off axis responses that is fairly similar to the on axis response and not much lower in level He is of the opinion that audio play back systems should have calibrated playback levels because our perception of bass and treble loudness changes with level as shown by the Fletcher Mu
137. s dynamic drivers or even automobile suspensions If the mass or the compliance of the system is increased the resonant frequency will the resonant frequency will increase the cartridge through the counterweight a resonance in the 8 16Hz range is a good susceptible to record warp If the reso nance is higher bass performance will be FIGURE 3 Anti resonance filter damping lost If it is lower warps will cause exces sive movement of the stylus with respect to the cartridge body leading to the gen u eration of large low frequency signals dis tortion and potential mistracking the face of the disk allow you to test cartridge performance as the geometry The tonearm on the 701 is an in mass of the counterbalance is reflected However unlike conventional fixed counterweight arms when the 701 arm encounters a record warp the flexible cou pling effectively reduces the effect of the counterbalance mass It is as though the mass of the counterbalance is not reflected back to the stylus for a fraction of a second while the warp is occurring This makes the arm act as though it had a higher reso nant frequency that does not respond to the low frequency warp During the large _ transitions caused by the warp the flexible x coupling slows the rate at which the force _ of the warp is transmitted to the counter balance much as the springs on your car limit the rate at wh
138. s resistance in that there is the audioXpress December 2010 E7 profit from selling exotic wires wire never fails so there is no warranty con cern the performance claims for exotic wires are boundless and explanations stretch the laws of physics and if the customer believes he or she will hear so satisfaction is almost guaranteed He said that almost all power amps can re veal audible differences between speak ers but others can cause audible differ ences that should not be there He dealt with the damping factor and amplifier power requirement calculations Part three expanded on room acous tics choosing loudspeakers subwoofer number and placement and other relat ed topics including problems with cen ter channel horizontal MTM designs the origin of the dipole surround speaker design and how to minimize seat to seat bass variations He showed a graph of an audio journalist reviewer s room not mine that with a single subwoofer exhibited wildly rough frequency re sponse over 20 80Hz with seat to seat variations among the five seats exceed ing 10dB With four corner located sub woofers and sound field management the seat to seat variations dropped to a maximum of about 3dB and the much smaller frequency response anomalies could then easily be corrected with rela tively simple equalization A point he emphasized a sad state ment about a mature audio industry is that t
139. s that you can read directly from the disc It covers the following speeds 16 66 33 33 45 and 70 59 to 90 RPM in 15 bands The published specifications note that the speed ac curacy can be measured to 0 03 by timing the drift of the display for one minute Photo 2 shows the disc and illuminator Clearaudio has a speed strobe test program strobo exe which was origi nally written for Windows98 but also uay SNTC SRU pie P 7 Ta HAA fA Al HAAS TEAL RTA NENS xS PHOTO 3 The Clearaudio LP and 300Hz light source which are available separately Because it s 300Hz you can use the light source for both 50Hz and 60Hz turntables LP and light bundle You can play the into account when setting the turn is for 45 RPM It does not work for quartz crystal controlled 300H2 bat tery operated and sold separately so FLI MUSIC PHOTO 4 The battery powered DI Glstrobo directly reads the rotational speed of the turntable you could easily use it with any stro two sided strobe disc like a regular LP so that stylus drag can be taken boscope disc for improved measure 300Hz you can use it with any strobo scope disc on turntables operating on x 50Hz or 60Hz power 78 RPM records The illuminator is Hifi4music markets the DIGIstro bo which is a rotational speed mea suring device adapted to audio use that is it directly reads and displays the turnta
140. s to a level of 45W which is more than adequate for the motor s required x 11W Additionally the TDA7396 device x has several built in protection features The LED fault indicating logic output _ circuit was not used in this design The DIY VPI HW 19 turntable I x have uses a Hurst Model PB 600 RPM LOW CLOCK output amplitude is too high A resistor divider network composed of R2 and R3 divides the 74HC393 s output voltage by two or about 2 5V peak to peak This keeps the from the TDA7396 power amplifier are 115V 60Hz 11W AC Synchronous Motor with part number SP 2871 The datasheet for this family of AC syn chronous motors is found at reference 7 Complementary outputs and connected to the secondary windings of an Acme Electric Amveco Toroidal Transformer model 62050 The trans Why are 60 of Superpower sales repeat orders or referrals Ask our customers I am speechless Really jaw dropping improvement Dynamics is superb Instruments more defined voices also better soundstage and also the bass Thank you once again for your excellent Support v Extremely low noise v Very low drop out v Infinitesimal Zout v Real specifications Above is a 1 2A step in less than 5us with only minor transients on Vout Dynamic You never heard it so good v Vout from 3 3 to 400V vy 2 amps output current Belleson www bel
141. services as the in dustry recognizes that they are in the content consumption business How ever DVD and Blu ray discs will not become extinct any time soon as they deliver the highest quality video and audio available to the consumer Wireless cutting the cord re quires a broadband Internet connec tion and has led to over the top no computer required access to stream ing content There are many free fee boxes services that support catch up viewing including Hulu www Hulu com Chumby www Chumby com Zinc V www Zinc tv Boxee www Boxee tv Verismo s VuNow STB http VerismoNetworks com Popcorn Hour www PopcornHour com and Sezmi www Sezmi com There are limits on what program ming each service delivers Much of the content is standard definition video and much of the HD content offers two channel audio instead of surround sound Connection speed and each ser vice s server farm capabilities affect the quality of service Caution is suggested because some of these and other com panies offering such services are likely to go out of business Sezmi is especially good for time shifted viewing A Sezmi TV every where subscription gives access to the supported channels and programs on all of the subscriber s devices It is a cleaner variation on the Slingbox www slingbox com especially when multiple simultaneous viewing is the household rule HDMI The HDMI Hot Seat pan
142. sic Direct see above or Ultra Systems Inc for the DIGIstrobo 127 Union 5 www tdl tech com strobe zip 6 The brass tubing is available from Small Parts 800 423 9009 www smallparts com as part 90670 562 692 5911 www mcmaster com as part number 4501K71 7 Marlin P Jones and Associates Inc PO Box 8 This PacTec enclosure type CM3 100 is available from Mouser Electronics 800 346 6873 www mouser com as part number 616 71914 510 039 EUROLAB Turntables since 1998 Design and manufacturing of custom TURNTABLES made from Slate amp Finland Birch Call for details CARTRIDGES Allaerts AT Ese Lab ARMS Jelco Rega e RS Scheu PHONO STAGES Ese Lab Nibiru PhonoMax Brocksieper Also available custom armboards feet VTA adjusters stone TT supports We rewire tonearms ATTENTION DlYers We sell bearings platters motors and even supply miniature lathes and milling machines for those with machining experience AUDIO ADVANCEMENTS LLC PO Box 2090 Branchville NJ 07826 USA 973 875 8705 audadv earthlink net www audioadvancements com audioXpress December 2010 21 Turntable Speed Control Build this variable frequency synchronous motor controller to control turntable speed ecently I acquired a VPI HW 19 motor platter bearings and other parts to build my own DIY turntable Subsequent to assembly I connected it to a strobe disc and noted that the turntable
143. sit our web site for further details HAMMOND MANUFACTURING v USA UK Tel 716 630 7030 Tel 01256 812812 Fax 716 630 7042 Fax 01256 332249 Canada Australia Tel 519 822 2960 Tel 8 8240 2244 Fax 519 822 0715 Fax 8 8240 2255 Tube Output Enclosed Plate amp Filament Open Transformers Chokes Transfomers Chokes IN STOCK Trar sformers amp Enclosures pr j j Tes Ventilated Bottom Chassis Rubber Chassis Covers Plates Feet Contact us for free catalogs amp a list of stocking distributors www hammondmfg com CONTENTS VOLUME 41 A DUAL 701 TURNTABLE TUNE UP Bring your turntable in for a tune up to extend its usefulness By Tom Perazella ALL ABOUT STROBOSCOPES Stroboscope solutions to determine correct turntable speed TURNTABLE SPEED CONTROL Building a variable frequency AC supply to control turntable speed By Joel Hatch THE WRETCHED EXCESS AR TURNTABLE RENOVATION Pt 1 Try this hands on approach to reviving a classic turntable By Tom Yeago VERTICAL BLENDING Is a blend control useful for vertical cut recordings By Don Walizer and Ron Tipton x RELIABLE REVIEVS OATLEY ELECTRONICS K272A HEADPHONE AMP Reviewed by Aren van Waarde HAVE WE GOT A DEAL FOR YOU Old Colony Sound Lab is now offering a Deal of the Day Great values on an assortment of products You can t afford to miss a single day So check it out at NUMBER 12 DECEMBER 2010
144. son The Sweet Spot Jan p 8 Perazella Tom A Dual 701 Turntable Tune Up Dec p 8 Preeda Karin 4D32 SE Power Amp April p 6 Visiting Thailand s DIY Tube Enthusiasts May p 9 A Push Pull 7591 Power Amp Nov p 6 Raczynski Bohdan Synthesized Bass March p 20 A Loudspeaker That Can Play Square Waves June p 11 Ramaswamy Ramkumar A Continuous Time Active Filter Aug p 14 Reeve Bill Ground Loop Basics By Example aX Digital Nov Rich David Audio On The Avenue aX Digital July Audio On The Avenue aX Digital Oct Review Infinity C336 Speaker aX Digital Nov Schilloff Andreas A Three Way Tri Amp Center Channel System June p 5 Sears Richard Signal Current Loops amp Power Signal Interaction aX Digital Aug Shand John Jazz Track aX Digital June Simon Ed Making Better Circuit Cards aX Digital April Power Amp Kits for Beginners Nov p 16 Smith Kent Amplifier Comparison Using Oscilloscope Waveform Plots May p 20 Staggs Darcy E AC Filters and Other Noisy Issues Jan p 34 Stamler Paul Power Supply Spreadsheet aX Digital March Sunier John Super Fidelity aX Digital May Super Fidelity aX Digital July Tipton Ron All About Stroboscopes Dec p 18 Vertical Cut Blending with Don Walizer Dec p 3
145. specified values Taking the low price of the kit into ac count the quality of the components is good Although the manual is well written it is not at Heathkit level Resistor color codes the polarity of electrolytic capacitors and the pin numbers of dual in line ICs are not explained Also no explanation of soldering techniques is provided Thus the kit is not sulted for first The Newest Products For Your Get Your Hanc On What s Next J 40 audioXpress 12 10 www audioXpress com time builders of electronic equipment However if you have previously built any circuit with good results you will have no problems with this one The screen print and the soldering mask of the PCB make as sembly very easy First mount the low profile components resistors diodes IC sockets then the capacitors and finally the active de vices Don t hurry take your time Although the kit is said to require only one hour of con struction time took an entire afternoon and worked very neatly It will pay off later Sonic Results Drawbacks and Measurements For initial listening tests used vintage Sennheiser HD465 headphones a pair of cans that is very comfortable and allows pro longed listening but is not ideal from a sonic point of view A Sony bitstream CD player served as music source My initial impression of the sound of the K2 2A warm pleasant and detailed Organ music sounded great On vocals and some orche
146. stral tracks there seemed to be an excess of bass However this could be a property of the headphones rather than the amp HD465s both the vin tage yellow model and the modern blue va riety sound rather bass heavy Thus switched to Grado R125 which is my best dynamic headphone www grad olabs com The 6418s had been in use for ten hours or so and were burned in With good CDs the K2 2A Grado combination produced excellent sound a fine bass power ful and deep but not overblown detailed mid range sweet top end Tonal colors of string instruments and vocals of male and female soloists were naturally represented Many small previously unnoticed details of record ings were revealed The message of singers in a choir was more clearly intelligible than with other headphone amplifiers which own and sibilants were not artificially emphasized In direct A B comparisons the K2 2A sounded better than the G4OEP 3 08 ax p 36 and even slightly better than the Stor class A amplifier 6 03 aX p 30 Less elec tronic more lifelike soent many pleasant hours of listening to audiophile CDs from BIS Brilliant Classics Chandos DG Telarc and Virgin Classics to mention just a few Yet It is not all gold that glitters There are a few drawbacks as usual In my opinion these are minor but you may judge differently First 6418 valves are very microphonic Oat ley advises kit builders to mou
147. sure to properly route the wires Once the lamp was in place I soldered the wires to the existing lead wires that fed the lamp contacts The result is shown in Photo 21 You can see that it all fits rather nicely I reinstalled the cover mak ing sure that the proper alignment for 60Hz was maintained You can see the lamp through the window in Photo 22 REASSEMBLY It was then time to replace the cover on the base I did not like the idea of using staples as was originally done at the fac tory If future access to the inside of the turntable ever became necessary I did not want to repeat the hassle of remov ing the staples Instead I decided to use small 2 wood screws At each point on the plastic cover where a staple had been I drilled a clear ance hole for the screws between the existing staple holes I then laid the cover on the base and marked the position of each clearance hole on the base I re moved the cover and drilled pilot holes for the screws at each of the marked locations I reconnected the signal cables to the RCA jacks and passed all the leads through the base I reattached the strain relief to the leads and positioned it on the cover I then screwed the cover in place with the small wood screws and I PHOTO 20 Factory neon lamp the original Phillips screws T removed the turntable from the sup The platter began to spin The tone ar
148. t by using the built in spring loaded clip For additional safety I removed the carrier holding the cartridee from the Shure Ultra 500 cartridge It was now safe to invert the turntable and place it on the special stand I made There are essentially two steps to re moving the bottom plastic cover The first is to remove the strain relief holding the power signal and ground leads in place so that they can pass through the base Next you must remove the staples and screws holding the plastic cover to the composite wood base Photo 2 shows the strain relief in place on the bottom plate In order to remove it I moved the two plastic lock ing tabs toward the center of the relief I then lifted the relief out of the base Photo 3 shows the retaining clip that keeps the power cable separated from the audio and ground cables I slid this clip off the track in the relief and then lifted it off releasing the cables The bottom is held in place around its periphery by a combination of staples screws and adhesive I used a small flat PHOTO 2 Strain relief on bottom Melbourne Burson Burson sounds good like a solid sate should Discrete Op Amp Modules IC bosed monolithic op amps are used in audio Simply the Best Op Amp in the World for various reasons ease of design ease of assembly and low cost however they suffer from EMI noise inconsistent quality an
149. t but the ma jority of programming will be in 2D for a very long time Content created for and shot in 3D such as most of Avatar will be much more visually effective in 3D than content created and shot in 2D and then processed for 3D pre sentation such as Tim Burton s Alice in Wonderland The 3D formats for Blu ray discs have been standardized frame packed 1920 x 1080p24 or 1280 x 720p60 for example the left eye image would be the odd numbered frames while the right eye image would be the even numbered frames The display process es and presents the images as appropri ate for its 3D display technology The Blu ray player and display must sup port HDMlv1 4a with 3D option for the 3D content s auto switching meta data to reach and control the display www audioxXpress com The 3D content s audio data delivery is the same as under HDMIv1 3 but if the A V receiver s or surround pro cessor s HDMI connections are v1 3 there might be a playback problem There are some 3D ancillary feature issues with Sony Playstation 3s no de tails given There are two 3D _ video frame compatible formats side by side and over under In the side by side 3D frame format each 1920 x 1080 video frame is made of a 960 x 1080 left eye image beside a 960 x 1080 right eye image thus reducing the image s hori zontal resolution by half In the over under 3D frame format each 1920 x 1080 video frame comprises a 1920 x 540
150. the products are distributed exclusively to specialty stores there will be no In ternet or big box retailers At CEDIA he showed the Triton Two tower speaker 2500srp pr that in cludes a built in 1200W powered sub woofer The tweeter is an evolution of the Heil tweeter which Gross calls a high velocity folded ribbon HVFR de sign liked the sound from the Triton Twos in stereo Gross played a record ing of a soprano with flute and violin ac companiment at a reasonable level the soprano sounded like she was standing just behind the plane of the speakers which were a couple feet forward of the front wall A chorus from the Rut ter Requiem Lux Aeterna Reference Recording s RR 57 HDCD 17 at www ReferenceRecordings com sounded a bit weak right in the center between the speakers don t know why The overall sound field seemed very slightly behind the speakers but not at all objectionable Current Audio www CurrentAu dio com has upgraded their in surface speaker cans to have a two hour fire rat ing which they claim that some local fire codes require for certain types of facili ties This reduces installation costs be cause one hour rated cans require dry wall fire rated boxes to be built around them to meet that code requirement Denon s http USA Denon com AH NC800 350srp over the ear dual noise canceling headphones Pho to 6 are claimed to offer 40dB noise PHOTO 6 Denon s AH NC800 he
151. through the wood base and motorboard This shows how fixed the motorboard to the base Accurate drilling of the pilot holes for the screws is essential You don t want to drill through to the finished surface 34 audioXpress 12 10 www audioXpress com PHOTO 7 The bottom of the work in progress motorboard more clearly showing the concrete backer board glued to the bottom and the method for attaching the motorboard to the wood plinth holes and pressed the heads into the ma terial deforming it until they were flush no countersinking needed I also cut and glued odd chunks of backer board to the bottom side of the motorboard still more DAP to add mass and damping The board is approx imately 18 in allowing plenty of room ers use this which is where I got mine and it s not exactly cheap at about 6 per _ square foot but it s easy to work plenty strong and well damped internally You can see from the photo that it also comes grained bits on the front and two in the back to bring the box to a workable size The boxes had an internal lip so I need I adapted the wood plinth from the boxes of some KLH Fourteen speak ers which I picked up cheap at a junk shop One dimension was OK but I let in other chunks of walnut the vertical Attaching the motorboard to the plinth isn t done in the usual fashion using screws and L brackets I used 1 screws inserted up from
152. tions supported by a product Five logos are shown on the HDMI website which of fers a download of the guidelines for each Stockfisch reported that Quantum Data is making HDMI test tools with the ability to test for HDMI 1 4a fea tures including 3D performance and compliance Whether journalists re viewers and consumers will be able to access Quantum Data s database of test results is as yet unspecified Marshall clarified that Wireless HD is HDMI over wireless not wireless HD the distinction coming from the 60GHz technology based on the IEEE 802 15 3c specification used to trans mit the HDMI signal carrying multi channel audio intelligent format and control data and lossless HD video up to 1920 x 1080p60 with Hollywood approved content protection within a room at distances up to ten meters from the Wireless HD website He said Wireless HD technology supports up to 4k x 2k video about 4x the pixel count of 1920 x 1080 and that the specification is accepted as a global standard He claimed that WiFi is mov ing to the 5GHz band and that the fu ture of wireless A V is in the 60GHz band at least within a room Chard spoke of the wireless home digital interface WHDI standard ver sus Wireless HD WHDI an RF based technology that operates in the 5GHz band and is similar to IEEE 802 11n technology supports uncompressed versus losslessly compressed HD video up to 1920 x 1080p60 while supportin
153. to about 22mm under the added mass Works swell And considering that the suspended mass is over twice that of a stock XA I com and thought about it a bit and a half octave lower than the stocker I figure the stock XA at about 3 5Hz ver to the center of gravity of the suspended u structure in relation to the springs If can expect a resonant frequency Just over sus about 2 4Hz for my unit I also glued base washers to the bot tom of the rubber and foam snubbers AR supplied And you know that foam It s important If yours is in good shape you need to keep it that way I ensured longevity by working some RTV silicone into the foam not filling the cells but x giving the plastic a good coating so the foam doesn t rot Don t get me going on x the tragedy of foam rot u Superb Specifications Outstanding Fit and Finish Swiss Like Precision And It Soundy Great Too The Technics SL 1200 SE Five Base Models Seven Genuine Upgrades Starting At 549 Wo Cll She Cudiephile Custom Preserving The Source OTA Lifetime www kabusa com Linear Audio your tech audio resource 170 PAGES 12 ARTICLES NO ADS JUST TECH AUDIO ae solid state amp tube power amps mc preamp low noise tube circuits active speakers test equipment stereo reproduction lt use discountcode AXA for 10 off audioXpress December 2010 31 Bob Cordell S
154. tput frequency and voltage for 60Hz and 100V AC respectively I de ener gized the circuit and disconnected the DC wall wart I mounted the output transformer within the enclosure and bolted it in place with a no 8 Phillips flathead screw Next I carefully routed the wires between the transformer and Manual indicates that the VPI motor AN2081 pdf above ambient during operation I m in the process of designing a heatsink to fit over or bolt onto the motor to help it dissipate heat I m very happy and pleased with the results aX frequency adjust potentiometer to the other side of the enclosure securing it REFERENCES in place with four self tapping screws AN1999 pdf 120V AC outlets I then screwed the endcap to the one end of the enclosure using four self tapping screws Noze I removed these screws during disassem bly of the enclosure Then I attached the endcap contain ing input power fuse on off switch and After checking the integrity of the en closure and circuit I reconnected the DC wall wart power supply and pow ered up the VFSMC The output voltage measured satis factory and I decided to operate the VFSMC for an extended period to make sure it didn t have any long term problems I performed an overnight check of frequency drift and output voltage and allowed a period of two minutes at the start to allow compo nents to warm up
155. triode portion of the circuit or the Electrode im pedance EZ To calculate the Total Circuit impedance TCZ including for instance the contribution of Rp at the plate as did use the change in current flowing out of the x total circuit under test which is that flowing through the 90K load resistor O ep2 90K Mr Morton addresses EZ s Zp from plate P to ground Zk from cathode K to ground and Zpk between the P and K When the calculations for Zp and Zk are repeated in a spreadsheet to strip out errors due to cu mulative hand calculations the results agree perfectly with the EZ portions from my let x ter and with those of RDHB4 if the RDHB4 equation 30 expression is corrected to rp 1 u Rk Yes gasp RDHB4 contains an x error You ll find the correct expression in the Priesman paper and in many other places or you can simply derive it yourself corneliusm cox net x Z k unequal to RDHB4 eq 34a Ro to which it was compared There are several rea i Mr Morton has presented a method for an alyzing circuit parameters that we can call Network and Feedback Analysis N amp FA i It has a computational simplicity that the 2 Algebraic Method AM used does not However N amp FA does not produce expres sions that give insight as to how each in dividual circuit component contributes to a circuit parameter And it forces you to re peat much of the
156. tter newly stuffed with DAP AlexPlus caulk sand mixture and topped with a disc of backer board A plastic cup is used as a dust cover and the improvised record weight is shown in the rear BEFORE YOU BEGIN turntables You ll need two motors and pulleys at any rate and the process will go better when you remodel the sub can also select the platter pieces which have managed to survive with less dam age or cosmetic insult So find two units who knows one of them may still sport that lovely gravure brass AR badge What you dont need or want to keep as spares you can unload on eBay You ll also need a small drill press scales capable of 1kg or so small taps 4 40 and 2 56 a dial caliper stainless ones are cheap these days but I prefer an old plastic example A razor saw and numbered drill bit set will make life easier too Pll mention other items as I go along Basically I took a stock AR XA did surgery sub chassis augmentation on the T bar to accommodate a 12 arm spruced up the bearings converted to a two motor drive system one belt added mass and damping to improve isolation and then built a new box or plinth And I also designed and built a 12 arm STARTING AT THE BOTTOM The sub chassis of the XA also known as the T bar is an aluminum casting that accommodates the three suspen sion springs and bearings for the table and arm Photo 3 The stocker has the
157. ttom of that wheel showing Next I cleaned and lubricated the assembly that controls the levers on the bottom of the cam wheel as shown in Photo 13 Note that one of the levers is connected to the tonearm and trips the cycle at the end of record play That level must move very freely or there will be dry that is it had no lubrication I did not apply any lubricant to that lever x to eliminate the possibility of drag that could result from its use The assembly shown in Photo 14 is central to the operation of the arm in When I was familiar with the operation of the various parts I removed the cam wheel to access the parts that lie beneath The wheel is held in place on its shaft by vertically pivoting arms The arm on the left is actuated by the cam wheel and automatic mode and proved to be the solution to my arm movement problem The photo shows a central horizontally pivoting plate to which are attached two PHOTO 12 Bottom of cam wheel moves both horizontally and vertically Because that arm is not pivoted in the horizontal direction its horizontal move ment is transmitted to the center plate the cam to stall partway through the cycle Use care when making this ad _ justment Once done properly the arm _ operation was flawless and from there to the right arm which provides the actuating movement for the tonearm In addition its vertical move ment is transmitted to the r
158. udspeaker s off axis fre quency response to be degraded Thus if this loudspeaker is pointed straight ahead and the listener is positioned off axis as is usually the case the first sound the listener hears is not very good and the second sound reaching the listener reflected off the near side wall is even worse partially because the wall typically does not reflect all frequen cies equally His point is that it might be better to aim the speaker s best sound directly at the listener even though that might make the second heard sound even worse a condition that equaliza tion and speaker repositioning cannot fix get a better speaker A traditional approach to deal with a loudspeaker s poor off axis sound is to attenuate the near side wall reflect ed sound with an absorber However they are usually acoustic foam no more than 1 thick roughly equal to 2 thick sculptured acoustic foam An acous tic fiberglass board absorber 1 thick has no beneficial effect below about 1kHz which effectively turns down the tweeter a 2 thick board has no bene ficial effect below about 500Hz which affects the midrange and tweeter In neither case does that fix the problem it still leaves a substantial mismatch between the first and second sounds reaching the listener For absorption to be an effective broadband attenuator it must reach down to no higher than 300Hz which requires at least 3 thick acoustic fiberglass mi
159. ul The whole process took about 45 minutes what with moving to a fresh spot on the wet or dry paper adding more water changing to 400 grit and finally add ing some Bon Ami to the water to give an abrasive to slurry This made for a nicely smoothed nub much better than stock The key here is patience Don t go nuts with the pressure don t try high revs or the thing will spin out of control and you ll get a nicely polished bearing surface Remove any remnants of the foam AR installed at the top of the well a dust barrier I suppose tape it over to seal out debris and you re done PLATTER MODIFICATIONS I left the two platter pieces pretty much alone The outer platter I left stock I to the floor before laying ceramic tile You want to mix up a fairly stiff batch of sand and caulk then weigh out six 85gm blobs Spread each blob out in one of the six segments of the inner platter Working from the outside in this will give you a good even fill and preserve the inner platter s balance Top off with the concrete disc which should settle evenly in This process adds about 700gm to the inner platter and goes a long way toward x killing any vibration that makes its way to the piece Because it s close to the center it doesnt contribute much to the flywheel effect but then again it s right there at the bearing so it does address bearing noise I spun the platter
160. und in a power cord or outlet violates NEC rules and increases the safety risk to technicians and consumers plus it will void insurance coverage if a fire results He debunked myths related to wir ing grounding and noise sources ex plaining that all grounds are not equal even two terra firma grounds several feet apart will have a measurable volt age between them and that a heavier ground wire will not solve the problem Another myth is the idea of impedance matching for audio interconnect cables showing that the goal is to transfer volt age not power and that termination for audio is not necessary until cable lengths exceed about 4 000 He pointed out that 10 of 12 speaker wire will exhibit substantial impedance above the audio band and an induced current can cause audible noise voltage to be fed back through the amplifier s feedback circuit getting amplified and delivered to the speak www audioXpress com ers He showed a spectrum of leakage noise current flow in a 3nF capacitor fed by a typical AC outlet with the level jagged but overall rather flat out to beyond 1MHz Whitlock described the noise prob lems in an unbalanced interface and how a balanced interface which he clearly and properly defined as equal impedance from each leg to circuit ground including the source output and the load input circuitry elimi nates the cause of the common mode interference The often used defini tion that a
161. vious version of the K272A can be found at the following URL htto diyaudioprojects com Tubes 6418 Tube Preamp Headphone Kit 2 For more information about the use of submin lature valves type 6088 and 6814 In crypto graphic equipment see the KWR 37 website htto www jproc ca crypto kwr3 html Manufacturer s response An excellent review thank you We respect Mr van Waarde s opinion and welcome constructive criti cisms recall answering somebody a long time ago about the filament being connected in series Here is some of the text for your consideration If VR2 were connected directly to ground the grid of V2 would effectively have a bias voltage of at least 1 2V with respect to pin 3 of the cath ode thus possibly cutting the tube off The way it is connected in the kit the Grid to Pin 3 of the Cathode voltage is OV same as the first stage The only difference between the two stages is that ef fectively the second stage has a lower supply volt age and thus produces a slightly lower gain The gains can be balanced by adjusting VR1 and VR2 If the filaments were connected in parallel the sup ply current would almost double The two stages would now be identical in appearance but their gains would be different anyway as no two tubes are the same Branko Justic Manager Oatley Electronics Pty Ltd wavVecor 42 audioXpress 12 10 High end speaker units for OEM and DIY WwWwWwW Wavecor com www audioxXpress
162. well as new Blu ray player models that can play 3D Blu ray discs and access content from Netflix VUDU and Pandora via a wire less LAN connection JVC www JVC com exhibited a 3D enabled D ILA projector Accell www AccellCables com in troduced a line of HDMI cables with swiveling connectors that bend and twist making it easier to fit the con nectors between equipment and the wall Their ProUltra Supreme cables are certified compliant with the HDMI High Speed specification Crestron s www Crestron com Core 3 control system line is based on Microsoft s CE build OS Crestron customized It supports object orient ed programming and prebuilt function objects to simplify dealer programming and shorten programming time The technology distributes audio video and control over Cat5e cable Core 3 supports the ITU T H 264 MPEG 4 AVC video codec standard but not VC 1 SMPTE 421 video codec stan dard The surround processing in the PHOTO 5 The Sharp Aquos Quattron display E10 audioXpress 12 10 www audioXpress com Procise series products is from Audys sey and supports 7 3 channels Speakercraft www SpeakerCraft com is well known for their in wall in ceiling speakers and has continued development of their NIRV control system developing an app instead of offering touchscreen controllers They also have added box loudspeakers to their catalog These changes led to their show theme Love Your Choi
163. x in shutdown standby mode After trou bleshooting the output fault circuit on the TDA7396 I discovered it required a 24 audioXpress 12 10 much lower load on the bridge circuit s outputs in order to function properly x I changed the output load resistor and performed initial measurements Subse quent to passing those measurements I connected the output transformer with a 3kQ load simulating the motor for test x purposes Photo 3 x PHOTO 2 Initial prototype board www audioxXpress com FIGURE 1 Turntable control circuit For the final build I decided on a simple circuit board using leaded components x This presents a minor problem with the _ LTC1799 oscillator which is only available in the SOT 23 5 package I found a suit able 5 pin SIP adapter at Digi Key part no 33205 www DigiKey com I designed a long and narrow circuit board to fit within the precut PCB slots inside the Radio Shack Inverter housing without any modifications The narrow circuit board also allows clearance room for the toroidal transformer The transformer is mounted roughly in the middle of the enclosure leaving room for clearance be tween itself and the AC outlets mounted in the enclosure s endcap and room for the circuit board on the other side I drilled a no 8 size clearance coun tersunk hole on the bottom of the hous ing for attaching the toroid transform

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