Hafler DH-100 User's Manual
Contents
1. JONV1Va OS 13NWOH5 SJILSV 1d 3dVHS n HOLIMS p 15 13325vH8 0 319NV p l e bb 0l 6 8 L 9 S L4 c l 0 9 G v 0 soyoul j N33u5 41815 3183uL 1VNINWH3L ILuo1v1nsNI Mls JSZ a v AN Qao ML 3c uu Y DE Nd 43034 SL31LNO OV NIVYLS 1 6 eget YBIAdOD INVHOVIG TVIHOLSId 034315 00L HQ H3 1S VH BUILDING THE DH 100 KIT Because many of the circuit components are already installed on the etched circuit board the essential per formance of your preamplifier has already been con irmed to meet specifications before it was packed in the it Most of the remaining assembly is simply mechanical but good solder connections are essential Read the pre ceding section carefuly if electronic kit construction is not familiar to you The pictorial diagram shows every connection and the parts that you will install on the circuit board The top of the board is marked with each component designation next to the mounting holes Separate lists for each parts bag will help you identify unfamiliar parts as you un pack them and these together with the pictorial diag ram which is sometimes distorted for clarity of connec tions should leave no question as to where each part goes In2. eem PREAMPLIFIER m Balance Series 2 v DH 100 PREAMPLIFIER OWNERS MANUAL LM163 Please refer to this serial number in all communications regarding this equipment THE DAVID HAFLER COMPANY Division of Rockford Corp le 4 e Z o 5910 Crescent Boulevard Pennsauken New Jersey 08109 A 353 d voL 613 South Rockford Drive Tempe AZ 85281 SPECIFICATIONS Specifications stated with load of 27K ohms in parallel with 1 5 nanofarads and for the band between 20Hz and 20KHz unless noted PHONO PREAMP SECTION Rated Output 3 Vrms Maximum Output 8 Vrms Harmonic Distortion Less than 0 005 RIAA Frequency Response 0 25 dB 20 20 KHz 0 1 dB 40 20 KHz Sensitivity 10 mV for 2 volt Record Out Maximum Input 180 mV 1 KHz Gain 34 dB 1 KHz Input Impedance 47 5 K ohms in parallel with 130 pF Signal Noise Ratio greater than 100 dB A weighted LINE AMPLIFIER SECTION Rated Output 3 Vrms Maximum Output 8 Vrms Harmonic Distortion less than 0 005 Frequency Response 0 25 dB 20 20 KHz Gain 20 dB Input Impedance greater than 35 K ohms Signal Noise Ratio greater than 100 dB A weighted INTERLOCKED F 33dB at KHz SELECTOR BUTTONS PHONO Pit gt H i Crosstalk down 80 dB Separation greater than 70 dB 1 KHz 55 dB 10 KHz Bass Control 10 dB 20 Hz moving inflection type Treble Control 10 dB 20 KHz shelving type GENER
3. UEIS 9 6 edeus 2135219 399 sqouy edeus 1 uouaJM uev Sdeo pue edeus youd ually ejBuy su 9 zzo 0 LZH LZLSW 69LSW LLLOW SLLAW 4LSIN 66LSIN vLLSW ON SJ LON ty e z LOLO er 9 1421 2 veo xnv 1 z 1431 er n 25 1H9IH er z e 1481 PEN asny dilo 5 jaued qns 1u014 uonq qouy jaued deo pug uoisn xe jaued juol4 ejejd jeued 19 02 SLYVd SNOANV11S OSI e OPERATION 6 0 POWER CIRCUITRY When the DH100 is turned ON the red LED will illuminate at the left center of the panel At the same time an internal muting circuit will limit the signal passing from the Preamplifier to your power amplifier for about 1 5 seconds until the Preamplifier cir cuits have stabilized During this 1 5 seconds you may hear the tuner or phonograph or other selected signal at greatly reduced level When the DH100 is turned OFF the muting circuit engages to protect the power amplifier against turn off tran sients If you turn OFF the Preamplifier and turn it ON again im mediately the muting circuit will still allow only reduced output for 1 5 seconds During muting time
4. SERVICE POLICY AND LIMITED WARRANTY The DH100 Preamplifier has been carefully designed to pro vide many years of use without maintenance or service Factory assembled units undergo rigorous testing before they are ship ped However damage in transit and human error can intervene to make service necessary It is the owner s responsibility to return the unit freight prepaid and insured to the factory or to the nearest factory authorized service facility Units shipped freight collect will not be accepted Shipment should be made by United Parcel Ser vice UPS wherever possible We will not be responsible for damage incurred in shipments by Parcel Post repairs in this case will be made solely at the owner s expense All shipments should be insured for the full value of the unit Use the original carton and packing material and enclose all of the following a Complete shipping address PO Box numbers are not ac ceptable b Serial number if not on unit c Copy of dated Bill of Sale for Warranty service d Description of malfunction If it is intermittent indicate this Warranty service is guaranteed for 90 days Warranties apply to the original purchaser only and are void if the Preamplifier has been modified without factory consent or if parts have been substituted which the factory considers unsuitable or if the Preamplifier has been physically or electrically abused or used for some purpose for which it
5. guarded by a 1 micro farad blocking capacitor C1 to protect both the Preamplifier and the cartridge THE DAVID HAFLER COMPANY will not assume responsibility for equipment damage of any kind if this capacitor is removed or defeated See ADDITIONAL IN FORMATION 9 90 9182 eAnisod 19 8 LdO AOQLIGAW 0 0 euejAdoudAjod zozo OZLVL Ieuuojsue1 LL vigo 916 901 LLETO ASZ GAW 027 oyoedeg LBL 990 E6EWT 10je1edujo 901 1748 AOS Q4W 0001 Yoyoedeg 1 9190 itive Beso fused M veis 19 80 ZESS BLOCEOW 91 101 SLLdO AOOLIGSW 2 euejKdojidAjod 9910 6 LdO AOQI LGAW 100 euejKdoudA od LL PLO 5 HEM Wily UOqUeD y 2 2 61035 019 018 91 1 ld A0O9H A LAJW VO euejKdoidAJod ELL ELO 19009 069 suJuo 068 dn ejddiu gan oq Eldo AODL LIGAW FO euejKdoudAJod ZLLZLO 20OH 009 SLUYO Y gr 168 SOOPNI apod 92120 AOOL IGAW O L ejeuoqieo AJod ZVODY 09 UOQUED suluo y 9 LdO AOSLIGAW 0 0 euejKdoud Ajod oyloedeg OLL OLO 21008
6. 033 mfd capacitors and install them at C20 and C21 17 0 Select the two 470 mfd capacitors Note that the negative lead may be marked and or the positive lead is longer The hole for the positive lead is marked by an arrow on the board at locations C18 and C19 Be sure these are oriented correctly 18 Select the four 1 mfd capacitors 1 0K and install them in the lower right corner of the board in the 2 locations marked C8 and in the 2 locations marked C11 19 The 12 phono jacks will now be installed at loca tions J1 through J12 along the back of the board It is important that these be mounted flat against the board and it is also important that a phono plug be inserted in the jack while the center conductor is soldered to the board Because the outside mount ing lugs of adjacent jacks share a common hole in the circuit board we suggest the following proce dure as the simplest way to make sure all of the jacks are properly aligned Install the jacks in pairs starting at J1 but tem porarily tack solder only the two mounting lugs the one hole at the center of each pair This will hold the jacks in position for checking and resol dering as necessary until they are all in a straight flush row The go back and solder the remaining mounting lugs securely After a final alignment check go down the line and permanently solder those lugs which were just tacked in place at first Now insert a phono plug one e
7. _ Reinstall the round plastic pushbutton on the switch shaft and select the 4 knobs the 4 set screws and the small L shaped Allen wrench Place a screw on the end of the wrench and thread it into a knob Install each of the knobs so that the set screw engages the flat on the control shaft 41 L Select the front panel the two end caps and the four large nuts Remove the long cap screws which were temporarily holding the front sub panel in place slip the end caps into the ends of the front panel and install the assembly on the chassis Be sure the LED protrudes through the front panel hole properly Fasten the assembly to the chassis with the four cap screws and their nuts using the large Allen wrench 42 L Install the long U shaped piece of plastic grommet over the top lip of the front sub panel Make a visual inspection of the diode orientation capacitor orientation the green wire which is connected to the B hole and the nomenclature on the controls as well as the general quality of solder connections on the bottom of the board Make sure the wire to hole H does not protrude too far Check that the fuse is in place 43 With 6 of the black sheet metal screws install the bottom so that the edges turn inward toward the top of the unit The narrow edge is to the rear Select the 4 rubber feet remove their backing and install them in the corners of the bottom plate about 1 in 44 Slide the cover on fro
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9. L Connect the short bare wire from AC outlet lug 4 to hole D on the circuit board S Connect the white wire from AC outlet lug 2 to hole F S 34 L On the bottom of the board connect the white wire from the ground lug to hole H Solder this on the bottom of the board Check to make sure that the bare wire cannot protrude above the top of the board so far as to risk contacting a phono plug in serted in that socket 35 Thread the line cord and white wire through the front grommet in the side piece Connect the white wire to the rear lug of the power switch S Con nect the line cord to the top lug of the switch S 36 Select the plastic wire tie and thread it through the two slots in the center of the left side piece to sec ure the line cord and the white wire This tie can be used only once and it locks securely when the tail is pushed through the head end from the flat side Cut off the excess after pulling it tight 37 Prepare 4 red wire and 3 1 2 green wire Start ing with one pair of ends even twist these wires together throughout their length At the even ends connect the red wire to hole A on the board near the power switch S Connect the green wire to hole B S Thread these wires through the rubber grommet in the front sub panel and connect the red wire to the farther lug 1 of the terminal strip Connect the green wire to lug 2 38 Select the red LED and n
10. before insertion into the back panel Then grip the larger diameter section with the tips of the pliers and squeeze tightly Avoid scratching the back panel when you insert the cord end and the smaller part of the strain relief through the hole AC from the outside Note that the hole has flats which keep the relief from twisting It snaps into position when fully inserted Separate the two conductors of the line cord Cut e the ribbed conductor so that 2 projects from the strain relief and strip 1 4 of insulation from the end Strip 1 4 from the longer end as well Twist the strands of each conductor tightly and tin each end with solder to secure the strands 2 Select the two right angle brackets and 3 sets of 6 hardware 1 2 black screws Fasten the long leg of each bracket to the inside of the back panel at either end of the long central cutout The third bolt simply fills the holes between the two rectangular openings for the AC outlets This hole has no pur pose in your kit 3 L Select the two AC outlets Note that one plug slot on each outlet is wider The wider slot goes at the bottom of the back panel when you snap them in from the outside Connect the ribbed end of the line cord to AC outlet lug 3 wide 4 Prepare a 2 length of white wire but strip 1 of in sulation from one end Connect the shorter bared end to AC outlet lug 3 S 2 Pass the longer bared end all the way through AC outlet lug 4
11. or smaller tip which reaches 700 F 60 40 60 tin ROSIN CORE solder 1 16 diameter or smaller 3 A damp sponge or cloth to wipe the hot tip of the iron 4 A wire stripping tool for removing insulation This can be a single edge razor blade but inexpensive stripping tools are safer faster and easier 5 A medium blade screwdriver about 1 4 wide 6 Needle nose pliers a long narrow tip 7 Diagonal or side cutting small pliers 8 Large gas or slip joint pliers 9 A 1 4 Spin tite nut driver may be helpful but is not necessary A soldering is not recommended The unfamiliar user is more likely to damage the etched circuit boards with its higher heat potential and unbalanced weight Also because he may not wait long enough for it to reach operating temperature each time it is switched on poor solder connections are more likely Pencil irons are much lighter and easier to use and there is no waiting time when solder connections follow in sequence as in kit building Make sure you have a holder for it though and always unplug it when you take a break Proper Soldering There are four steps to make a good solder connection 1 Make a good mechanical connection to hold the wire in position while heat and solder is applied 2 Heat the junction of the wire and lug or circuitry on the board with the bright shiny tip of the iron 3 After heating for a couple of seconds apply solder to the
12. solder Allow the excess to flow away onto the iron When properly done the wire is uniformly bright and no larger than before The hookup wire supplied with this kit does not normally need tinning as it is pre tinned It is a good idea to check off all the parts before you begin to make sure that nothing has been overlooked and to help you identify any unfamiliar items by compar ing them with the list for each parts bag and with the pictorial diagram If a part is missing a postcard or a phone call to Customer Service at 609 662 6084 will bring a prompt response 1 Owners Manual KIT PARTS LIST This list is in addition to the individual lists included in each of the parts bags 1 through 4 Part No Part No 1 Circuit board assembly PC 23 KF343 1 Fuse spare 1 16 amp slo blo SF019 1 Cover MS174 2 End cap front panel MC111 1 Back panel MS199 4 Knob metal HD117 1 Bottom plate MS173 1 Line cord with plug WA043 1 Front panel ME118 1 Transformer power 120 volt TA126 1 Front sub panel MS169 or alternate 240 volt TA127 2 Side pieces MS171 1 Label serial number LRO15 1 Allen wrench L shape 5 32 HZ138 1 Registration card LMO16 1 1 Cable pair audio WAO17 ve CWC usw 5910 Crescent Boulevard Pennsauken New Jersey 08109 609 662 6355 Division of Rockford Corp 613 South Rockford Drive Tempe AZ 85281 9l Gl vi El LLO 62 82 Lz 92 Sc cl LL 0l 0 JWNTOA
13. some cases a specific orientation of a part is called for and the circuit board will identify the lead or marked end However some part manufacturers will instead identify the opposite or lead on the compo nent so be sure you install these parts correctly Mechanical connections in a preamplifier must be tight because many of them conduct electrical signals even through the chassis The exception will be the nylon screws and nuts used in special cases where they should be tightened only until they resist your tools slightly to void stripping their threads It will be easier if you first eparate the hardware by size and type in an egg carton verifying the count on the parts list as a check on how they are identified 4 and 6 nuts look almost alike but the larger 6 size can be selected by sliding it over the single long 4 screw 1 L We ll tackle the most difficult step in this kit right away installing the AC line cord and its strain re lief This requires heavy gas or slip joint pliers be cause of the stiffness of the line cord Select the back panel the AC line cord and the plastic strain relief 9 from the cut end of the cord make a sharp V in the line cord by bending it back on itself with the ribbed conductor positioned as shown Install the strain relief with the smaller diameter nearest the cut end of the cord Crimp the two halves of the strain relief around the cord at the V to partially form it
14. what signal you hear may sound distorted Such distortion is normal and does not in dicate a Preamplifier problem it will disappear when muting is completed 6 1 SIGNAL SELECTION PUSHBUTTONS The function of these controls has been discussed in Section 4 0 The Line level inputs TUNER AUX and TAPE all have the same input circuitry When any switchis NOT selected its input is left floating not grounded as in most preamplifiers but an isolating ground is imposed between the incoming signal and the Preamplifier to eliminate inter source feedthrough The reason for providing this kind of input is to accommodate signal sources that will not tolerate a short circuit to ground at any time such as some tape recorder and computer outputs 6 2 VOLUME CONTROL This control has a smooth continuous rotation The unity gain position where Line input and output voltages are the same is at about the 11 o clock setting of the VOLUME control 6 3 TONE CONTROLS The tone circuit in the DH100 is unusual in three respects it is not switched IN or OUT it has an amplifier dedicated to tone operations only and it uses a unique balanced circuit to obtain boost and cut The reason many preamplifiers provide tone switching is that tone circuits tend to interfere with the bandwidth or overall fre quency response of the preamplifier This is not the case in the DH100 Neither response nor distortion are deteriorated by the tone circu
15. AL SPECIFICATIONS Semiconductors 7 integrated circuits 5 diodes 1 LED Inputs Phono Tuner Aux Tape Outputs Record Line Controis Volume Balance Treble Bass Input select by push button Tape Monitor Power AC Supply Voltage 95 130 or 190 260 VAC 50 60 Hz Power Consumption less than 5 watts AC Convenience Outlets 2 switched Size 13 9 16 x 3 x 10 inches Shipping Weight 9 Ibs Net Weight 7 Ibs DH100 FUNCTIONAL DIAGRAM RECORD 0 dB 4 VOLUME BALANCE t m TUNER gt rip i LINE i in i L 20 dB AUX 2 aux TREBLE TAPE MONITOR s BASS Mute TAPE WARNING To prevent fire or shock hazard do not expose this equipment to rain or moisture Copyright 1988 All rights reserved CONTENTS Additional Parts List Operation Noteson the Circuitry Specifications Functional Diagram Installation Component List Parts Placement Diagram Schematic Diagram Additional Information Warranty and Service Policy INTRODUCTION The DH100 Preamplifier must surely represent the highest quality per dollar of any audio product manufactured in this decade Initial response to the performance of this unit during evelopment and testing has been unusually enthusiastic The 0 5 arises from the meticulous application of good engineering practice respect for the fragility of the audio signal simple straightforward circuitry careful component selection and testing g
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18. TAPE input which manages with only one 7 3 CAPACITOR SELECTION Capacitors with polypropylene and polycarbonate dielec trics have been used wherever possible to take advantage of their low distortion Such use is very rare in economical audio components and contributes significantly to the sonic qualities of the DH100 ADDITIONAL INFORMATION 8 0 The following paragraphs discuss some of the answers to frequently asked questions regarding connection of peri pherals to the DH100 amplifier If you have a problem read this section carefully before contacting the Factory 8 1 PHONO INPUT CAPACITOR Coupling Capacitors C1 Left and C101 Right are placed at the input to the Phono stage to provide DC isolation between the cartridge and the input amplifier The value is 1 0 mfd When this capacitor is jumpered thus removing it from the circuit several problems may arise Some turntables short the car tridge leads to ground when the tone arm is in the rest position With the capacitor removed this grounding may upset the balance of the Phono amplifier and produce a dangerous tran sient to the power amplifier enough to damage a loudspeaker Other times this grounding may produce an unpleasant hum There is a small and usually harmless direct current flowing from the input stage through your cartridge without this capacitor but unless you have engineering knowledge of the parameters involved you cannot rely on the safe
19. an Interna tional transformer is available which accommodates line voltages between 200 and 260 volts Hafler Part Number TA127 It is recommended that the Preamplifier be connected directly to a wall or floor outlet and not to an extension cord articularly if the Preamplifier is being used to switch a power mplifier 2 1 ACCESSORY OUTLETS Two outlets are provided both controlled by the Preampli fier POWER switch and adequate to operate a DH 120 XL 280 or DH 500 power amplifier and a tuner or tape transport In some countries the AC convenience outlets are not provided 3 0 OUTPUT CONNECTIONS Output jacks are labeled L for left channel and R for right channel 3 1 LINE OUTPUT These jacks connect to the power amplifier input jacks of your system The signals at the Line Outputs are affected by the BALANCE VOLUME BASS and TREBLE Controls andthe MUTING circuit Note that the DH100 is not meant to drive audio cables longer than six feet 3 2 RECORD OUTPUT CONNECTIONS These are signal outputs to a tape recorder for making re cordings from PHONO TUNER and AUX inputs You willusea line input on your tape recorder not a microphone input and adjust the tape input level controls for a good meter reading Note that a tape recorder or other signal Source connected to the TAPE input of the DH100 may not be recorded The MUTING circuitry does not protect the RECORD outputs 4 0 LINE INPUTS A LINE LEVEL i
20. ance will drop slightly Input jacks are labelled L for Left and R for Right Chan nel signals 5 0 PHONO INPUT The PHONO input is meant to accommodate standard mov ing magnet cartridges with signal outputs in the 5 millivolt range Some high output moving coil cartridges will operate satisfactorily with the DH100 as well although VOLUME set tings will be in the upper third of the range of that control Nor mally use of a moving coil cartridge will require a pre pream plifier head amp or step up transformer Your dealer will be glad to tell you about suitable products for this purpose A grounding lug is provided on the back panel under the Right PHONO input normally used to connect the ground wire from the turntable to the Preamplifier chassis Sometimes the user encounters unpredicted behavior in the turntable preamplifier connection In case of difficulty see the section on PHONO in stallation ADDITIONAL INFORMATION later in this Manual 5 1 CARTRIDGE LOADING The input impedance is 47 500 ohms in parallel with 130 picofarads This resistance value is standard for most car tridges The capacitance 130 pf when added to customary cable capacitances in the leads between turntable and preamplifier will bring the total capacitance value within the range recommended by most cartridge manufacturers To customize these input specifications see ADDITIONAL IN FORMATION The PHONO input is
21. and 3 8 beyond that lug bend the wire downward at a right angle Solder lug 4 5 Prepare a 1 3 4 white wire Connect one end to AC outlet lug 42 pointing the wire toward the angle bracket 6 0 Prepare a 1 1 4 white wire Connect one end to AC outlet lug 2 S 2 Connect the other end to AC outlet lug 1 L Prepare 9 white wire Connect one end to AC outlet lug 1 5 2 LM164 8 Select the ground lug the longer bright screw a 4 KEP nut and the knurled thumb nut Fasten the ground lug on the inside of the back panel with the screw head on the inside secured with the KEP nut on the outside at the lower hole labeled GND The ground lug should point toward the strain re lief Be sure this connection is tight Then place the knurled thumb nut on the screw 9 Prepare 1 1 4 white wire Connect one end to the ground lug so that the wire projects towards the strain relief S Set the back panel aside temporar ily 10 0 Select the bright finished front sub panel and one of the rubber grommets Orient the panel so that the two single holes are in the upper left corner and install the grommet in the larger of the two holes 11 L Select the two lug terminal strip and one set of 4 hardware Mount the terminal strip next to the grommet on the outside facing you with the grommet in the upper left of the panel below its mounting hole 12 Select the power switch and two 4 s
22. ay be removed from a connection by heating it and allowing the solder to flow onto the iron which is then wiped on the sponge ALL SOLDER USED MUST BE ROSIN CORE Never use acid core solder or any separate flux in elec tronic work Silver solder is not suitable If in doubt about unmarked solder always obtain a fresh supply of rosin core solder We recommend 60 40 for easiest use Do not confuse it with 40 60 which is harder to melt The general procedure is to use a hot iron for a short time to heat a connection then add solder with the iron still in contact Remove the solder once it flows and then remove the iron A cooler iron applied for a longer time is more likely to damage components or lift the copper cir cuit pattern from the board A break in the etched circuit can be mended by simply soldering a small piece of wire across it Do not allow much build up of solder on the tip of the iron or it may fall onto adjacent circuitry and cause a short circuit Assembly Tips A set of hardware includes a screw and a KEP nut which has a lockwasher attached Always install the lockwasher side first Screws are always inserted from the outside of the chassis unless otherwise specified in the instructions 4 hardware is smaller than 6 and in this kit the 46 screws are finished in black to match the COVer Allen wrench L shape 8 set screw 2139 To prepare a wire means that you are to cut the desig nated length f
23. crews Mount it on the inside of the panel below the terminal strip so that its two connecting lugs are upper most behind the terminal strip Set the front panel aside temporarily When installing components on the etched circuit board be sure you are using the correct holes then make sure the part is oriented correctly if that is specified place the part flat against the board solder the leads on the underside of the board and cut off the excess lead This board has plated through holes which means that the hole is coated with metal on the inside Solder will be drawn into the hole when it is heated along with the lead SO you do not have to leave a large mound of solder on the outside Just be sure the connection is smooth and bright It is expected that you will solder every component lead which passes through the board so individual instructions will not repeat that point 13 Select the circuit board and the 4 diodes which are marked with a stripe on one end The stripe must be on the end which is nearest the center of the board when these are installed in the locations marked D1 D2 D3 and D4 below the transformer location in the upper left corner Solder every lead 14 L Select the disc capacitor 502M and install it between the diodes 15 Select the 2700 ohm resistor which has color bands red violet red and install it at R39 near the left front corner of the circuit board 16 L Select the two
24. d a grounding plug inserted in the Right input jack In either case only the Left loudspeaker will be active If one mono signal is applied to AUX left and one to AUX right jacks then the BALANCE control will select one the other or a mixture of the two two inputs for one A more satisfactory input configuration is through the use of a Y interface cable This device accepts a mono input plug and branches out to two plugs one each for the Left and Right Preamplifier jacks on a Line input The advantage is that both loudspeakers will reproduce the mono signal source In this case only one device may be connected per Line input Home computers with sound output may be connected to the DH100 Such outputs vary widely from one computer to another so you Will have to consult a dealer or the computer schematic diagram to see what the signal parameters are We have eliminated one potential problem for you by seeing toit that the input signal is never grounded when not in use Keep in mind that the computer output level may be much higher than typical for audio components In this case a resistive voltage divider may be used to reduce the signal level FIG 8 4 shows a typical connection Ry should be kept at 10000 ohms and Rx varied for a good signal level It would be possible to adjust Rx so that computer level is the same as the TUNER or PHONO at similar VOLUME control settings FIG 8 4 also shows Rx and Ry com bined in a level control pot
25. enerous circuit card topology and use of precision tolerances where they contribute significantly to performance The design philosophy of the DH100 exemplifies simplicity and economy To achieve this we have provided only those func tionsthat are primary to a good audio system and wehave been most careful to see that the integrity of the electronics con forms to a high standard Although it might be thought that a low cost preamplifier would not find its place among higher priced components the DH100 may change such thinking for its ability to preserve the detail rendered by expensive cartridges power amplifiers and loudspeakers is most impressive We invite you to compare its performance with the highest rated preamplifiers and to tell us of your findings INSTALLATION 1 0 MOUNTING The DH100 Preamplifier is intended for table top or shelf mounting No rack mount provision is made It is important that the Preamplifier not be placed directly on top of power amplifiers or other high current devices otherwise hum fields may be intercepted by the Preamplifier and heard in the loud speakers It is not necessary to provide much ventilation to the DH100 however it is a good rule to allow air circulation around any electrical device 2 0 POWER CONNECTIONS Preamplifiers are supplied with transformers for standard United States line voltage Wide variations are tolerated be tween 100 volts and 130 volts For overseas use
26. entiometer which must be mounted exterior to the Preamplifier perhaps in a junction box of some kind R FIG 8 4 COMPUTER INTERFACE i t Rx To AUX oic R M y P Vc C 1 5 mF Ri R 4 7K I 1 Ves 5 12V To AUX 10k Ry 8 5 HEADPHONE CONNECTION The DH100 has no output jack for headphones The Line out puts will however drive high impedance headphones 200 to 2000 ohms to a level satisfactory for normal listening It is assumed that if you use the DH100 for headphone listening you are not also using it with a power amplifier The DH100 controls make it a very good preamplifier for headphone use There are conversion boxes available from your dealer for connecting headphones to the power amplifier and these will prove to be a satisfactory way to use both loudspeakers and headphones on the same system including standard low impedance phones 4 ohms 8 6 PREAMPLIFIER OUTPUT CAPACITOR In this day of higher and higher audio power protection cir cuitry is a most important feature of HAFLER equipment The protection circuitry in our preamplifiers and power amplifiers is meant for the benefit of both these units and your valuable loudspeakers For this reason you should never defeat the coupling capacitors in a HAFLER preamplifier or power amplifier The DH100 Muting circuitry requires the coupling capacitor to prevent DC output to the power amplifier REMOVAL OF THIS CAPACITOR MAY INVALIDATE YOUR WARRANTY
27. er than rosin core solder has been used Units assembled with acid core or silver core or paste flux will be returned unserviced This warranty gives you certain rights You may also have other rights the extent of which may vary from state to state THE cavi aerem COMPANY 5910 CRESCENT BOULEVARD PENNSAUKEN NJ 08109 609 662 6355 Division of Rockford Corp 613 South Rockford Drive Tempe AZ 85281 THE HAFLER DH 100 PREAMPLIFIER KIT BUILDER S MANUAL LM164 ASSEMBLY INSTRUCTIONS There are three basic rules for success in electronic kit building 1 Read the instructions carefully and follow them in or der 2 Make secure solder connections which are bright and smooth 3 Check your work carefully after each step The DH 100 preamplifier is a versatile component with sophisticated circuitry which has been made remarkably easy to build by individuals with many years of experi ence in the design and engineering of the finest perform ing audio kits and in the preparation of their manuals Kit building should be fun and we are certain you will find this to be so Fatigue increases the risk of error so take a break rather than push to early completion There are relatively few separate components in this design to make it easy to pack everything away if need be Your work area should have good lighting and the pro per tools The tools should include 1 A 40 to 60 watt pencil soldering iron with a 3 16
28. itry and when the controls are in their center detented position response is flat within 0 1 dB A balanced circuit is obtained by using an operational amplifier in a differential configuration This type of control per mits a simple economical parts symmetry with adequate feed back for low distortion Precision tolerances are usedin this cir cuit to provide a flat response at detent position and to provide similar characteristics from unit to unit The controls are tapered so that small changes will occur in the area of the de tent with boost or cut becoming more evident as the control is moved away from center As a general rule extreme settings of the tone controls indicate a frequency response limitation in some part of the system usually the signal source or the loudspeaker When high settings are used it is most likely you are listening to large amounts of hiss and rumble and not too much music The minimum amount of boost and cut necessary for enjoyment is the best 6 4 BALANCE CONTROL The BALANCE control adjusts the relative amount of Left and Right loudspeaker volume We find that customers have a hesitation in using this control and it should not be so The pur pose of balancing the sound is to make the image of the music seem centered in your listening area The placement of the speakers and furnishings in the room your listening position in the room all affect the position of the stereo image It is legitima
29. junction It should melt immediately and flow smoothly around both surfaces 4 Allow the connection to cool undisturbed Remember that the connection is made by the solder not by mechanically attaching the wire to the terminal Usually the wire is looped through the lug and crimped in place but some prefer to just place it through the hole and rely on the stiffness of the wire to hold it while solder ing Connections to the circuit board of course are handled this way Good solder connections are essential for trouble free noise free operation A good solder joint does not require much solder around the conductors Never butter par tially melted solder on the joint as it is useless A good connection looks smooth and bright because the solder flows into every crevice when the parts are hot enough Continued on back page Popp The iron must have a bright shiny tip to transfer heat easily to the junction That s why the damp sponge should be used frequently to wipe the tip and occasion ally you must add a small amount of solder to the tip too If a connection is difficult to heat wet the tip with a small blob of solder to provide a bigger contact surface to the joint Once the solder flows around the conductors any movement must be avoided for a few seconds to allow a good bond When cool check the connection by wiggling the wire If in doubt or if the connection is not shiny re heat the joint Excess solder m
30. lect the front sub panel assembly and the 4 large Allen socket head black screws Mount the sub panel to the board just sliding the screws into their corner holes They need not be secured with nuts at this time 28 Select the 4 nuts and 4 washers for the controls and secure the controls to the panel 29 Solder all of the remaining lugs of the 4 front panel controls to the underside of the circuit board 30 Select the power transformer and the two long nylon screws and two nylon nuts Note the lug numbers on the transformer Position the trans former so that these match the numbers on the cir cuit board and solder each transformer lead after making sure that the transformer is flat against the board In the 100 120 volt version used in the USA there are no lugs at positions 2 and 3 Install the nylon screws from the bottom of the board and secure with the nylon nuts but do not overtighten these NOTE If the transformer supplied with your kit has lugs at positions 2 and 3 it operates only from 200 260 volt AC mains 31 Select the back panel assembly and 4 sets of 6 hardware Feed the end of the AC line cord and the white wire through the rear grommet in the side piece from the inside making sure the angle brackets are on top of the board and secure the back panel to both side pieces 32 Select the two sets of 4 hardware and fasten the back panel angle brackets to the top of the circuit board 33
31. m the rear and secure it with 4 sheet metal screws on the bottom and one at the center rear Affix the self adhesive serial number label to the center rear of the bottom You may wish to secure the small Allen wrench for the knobs to the bottom of the unit with tape for future con venience CONGRATULATIONS Enjoy this truly outstanding preamplifier CERNE XII faune 5910 Crescent Boulevard Pennsauken New Jersey 08109 609 662 6355 Division of Rockford Corp 613 South Rockford Drive Tempe AZ 85281
32. nd of the audio ca bles supplied in the kit fully into each jack as solder the center conductor of each TACK SOLDER 20 Select the four gang pushbutton switch and note that the flat metal mounting bar will be tight against the top surface of the circuit board when the switch assembly is installed correctly Initially tack solder two opposite corner switch lugs and check to make sure the switch assembly is flush against the board and that all lugs project through the board When you are certain that it is correct solder every switch lug securely 21 L The 4 potentiometers or controls may look alike but only two are identical The balance control will be marked 50K as a part of the printed numbers on the control but otherwise it looks like the O bass and treble pots The volume control is also 50K but it does not have the metal disc on the back Install the volume control in the right corner of the board first Because control position is critical for proper mounting to the front panel and it is very difficult to make any change after multi ple lugs are soldered we suggest that you solder only one lug on each control as you install them at this time Even so take care to position each so that it is flush against the board and so that the control shaft is parallel to the surface of the board Select the 50K balance control and install it in the center location Then install the two 25K pots in the bas
33. nput is a general purpose input as opposed an equalized input like PHONO which expects a standard nominal voltage for proper operation Most equipment for use with a preamplifier tuners tape decks etc have an out put that more or less conforms to this standard voltage All the line level inputs TUNER AUX Auxiliary and TAPE in the DH100 have the same signal capability and may be used for other than their labelled purpose For instance a tape recorder or video sound source may be connected to any of these inputs The sound output from most home computers may be connected to these inputs as well see ADDITIONAL INFORMATION You must observe Left and Right Channel symmetry ie connect Left to Left and Right to Right between the DH100 and any signal source connected to it The PHONO TUNER and AUX switches are self cancelling that is the last button pushed releases the previous button Note however that the TAPE switch is not part of this self cancelling group and that it supersedes any other input you may have selected Be certain to check the position of this switch if your preamplifier sometimes seems inoperative While the nominal signal level for aline input is 50 millivolts higher level signals may be accommodated because they pass through the VOLUME control before being amplified The input impedance is approximately 35000 ohms When a tape recorder is connected to the RECORD outputs this im ped
34. ote that adjacent to one lead the red flange has a tiny flat which marks the cathode lead This lead will be connected to the green wire and thus to hole B on the board To position the LED properly so that it will engage the hole in the front panel hold the LED pointing to ward you with the flat on the right side Bend the lead upwards at a right angle 1 8 behind the red base flange Then bend the leads into an open V so that they may be pushed up through the holes in the lug terminal strip When the tip of the LED is 1 2 above the top surface of the square plastic switch shaft bend the LED leads sharply outward to support the LED while it is soldered This should position it so that the rear surface of the red flange is in a vertical line with the front of the switch handle when it is out released Solder the red and green wires to the lugs as well as the two LED leads Before you cut off the excess LED lead length it is best to check by temporarily putting the front panel in position after placing the black plastic switch pushbuttons on the switches for alignment POWER SWITCH 39 Remove the round pushbutton from the power switch shaft and select the piece of black plastic shrink tubing Cut a 1 4 length of tubing and slip it over the LED so that it touches the upturned leads at the rear Hold a lighted match below it and it will shrink to fit and thus prevent extraneous glow from the rear of the LED 40
35. rom that color supplied and strip about 1 4 of insulation from each end The wire supplied in the kit is 18 white and 22 red and green so you can set adjust able wire strippers accordingly The line cord is 16 Be careful that you do not nick the wire when you strip it that can happen more easily when you do not use wire strip pers for that weakens it The wire supplied in the kit is bonded stranded which provides greater flexibility with resistance to breakage for easier use Whenever a connection is to be soldered the instruc tions will so state or will indicate by the symbol S If more than one wire is to be soldered at the same point the indication will be 5 2 or 5 3 If soldering is not called for other connections have yet to be made to that terminal They would be more difficult if the connection was already soldered but some builders prefer to solder each connection as they go Every connection in the kit will be soldered when it is complete Every lead which connects to a hole on the circuit board is to be soldered After soldering a connection clip off any excess lead length for neatness and to minimize the possibility of a short circuit Tinning refers to the process of applying a light coat ing of solder to a bared wire end On the line cord for example it keeps all the strands secured and also makes a good connection easier Simply touch the wire with the iron for a couple of seconds and apply
36. rts Placement Diagram for the position of these resistors The input loading capacitors C2 C102 may also be changed if necessary The total load capacitance on a cartridge is the algebraic sum of three separate capacitances a the capacitance of the cable between the turntable and the Preamplifier b the value of C2 or C102 and the input capacitance of the DH100 phono stage without C2 a Typical cable value is 150 pf a 150 b Present value is 120 picofarads b 120 c Input value without C2 is 10 pf c 10 Total capacitance 280 pf Required values for proper cartridge loading can lie between 100 and 470 picofarads While it is desirable to have the value close to the manufacturer s recommendation this value is not critical When replacing these components use a good polypropylene capacitor for C1 and C2 anda metal film resistor for R1 8 4 MONO OPERATION A preamplifier in MONO mode usually combines the Left and Right Channel information and delivers this summed signal to both outputs Its use is limited to older phonograph recordings and to a few inputs which are available in MONO only such asa monaural tape deck video sound signal and computer sound outputs There are two options open to the user if a MONO sourceis to be used The easiest option is to connect the signal to the Left input jack and listen to the source with the BALANCE control fully counterclockwise Or the BALANCE control may be set at center an
37. s and treble positions 22 Select the two large 1000 mfd capacitors and not ing the lead arrows on the board install these at C16 and C17 just below the diodes 23 Select one of the side pieces and two sets of 4 hardware Position the side piece on top of the left edge of the board with the flanges pointing out ward and with the rectangular cutout above the designation for Regulators 126 and Bolt the side piece to the board 24 Select the two rubber grommets and install them in the holes in the side piece 25 Select the two regulators IC6 and IC7 their 2 flat plastic insulators 2 insulating shoulder washers and 2 sets of 4 hardware Install IC7 designated 7815 on the inside at the rear of the cutout in the side piece The flat side of the regulator is towards the side piece when the leads are inserted in the correct holes on the board Install a shoulder washer on a screw with the larger diameter next to the screw head Hold a flat insulator between the IC and the side piece and insert the screw from the inside through the IC the insulator and the metal side Fasten snugly with a nut but don t overtighten Solder each lead on the bottom of the board Install IC6 7915 in the same manner in the adjacent front location 26 Select the other side piece and two sets of 4 hardware Mount it on the board with the rectangu lar cutout toward the front of the board at the top 27 Se
38. te to use the BALANCE control to make this image comfortable for you Not all phonograph recordings and broad casts are balanced at their source so you may want to correct forthis with the BALANCE control Usually experiment will dic tate a normal setting in your room When the control is fully clockwise only the Right Channel in formation will be heard from the right loudspeaker If it s com ing from the left check the connection of your cables Some thing is reversed A fully counter clockwise setting produces only Left Channel information from the left loudspeaker The center detent provides equal level to both loudspeakers with an accuracy of 0 1 dB Careful interconnection is the best way to insure that Left in formation will be on the left and Right information on the right An additional check can be made if you own recordings of a symphony orchestra for virtually every orchestra of this type places violins on the left and cellos on the right of the stage Careful listening will confirm this location for these in struments if Left and Right signals are correct NOTES ON THE CIRCUITRY 7 0 PHONO STAGES Two operational amplifiers make up the phono section of the DH100 The RIAA equalization is passive in this preamplifier which means that feedback is not used to determine the necessary response curve for playing phonograph records All the passive components in the PHONO circuit carry 1 tolerances The use of passive circ
39. uitry offers considerable design freedom when using integrated circuits and permits these chips to function adequately in a quality preamplifier by not asking a single chip to too much Two stages also pro vide exceptional input output isolation and a slightly better in put overload characteristic The gains of the two stages have been selected to provide in our opinion the most practical divi sion for gain noise and overload specifications DC coupling has been preserved to eliminate both the cost and compromise of yet another coupling capacitor Special care has been taken to insure close tolerances to the RIAA characteristic in the critical mid band region 7 1 POWER SUPPLY We are mindful of the beneficial influence of a clean power supply with good dynamic regulation and the accompanying low impedance at all audio frequencies The dual tracking regulator in the DH100 tolerates a wide range of line voltage variations To maintain low impedance at high frequencies we have employed low ESR electrolytic capacitors and bypassed the power carrying traces at frequent intervals with polypropy lene capacitors The ground traces have been drawn at five times their required size to ensure very low ground path im pedances 7 2 SWITCHING A deliberate effort was made to keep the number of switch contacts in the signal path to a minimum this meant eventu ally only two switches for each signal to pass through except the
40. value of this current PLEASE NOTE THAT THIS MODIFICATION eliminat ing these capacitors MAY INVALIDATE YOUR WARRANTY 8 2 PHONO GROUNDING Nearly all turntables have three cables connecting them to the preamplifier one each for Left and Right Channels and a third single wire for grounding The single wire is meant to be secured under the thumb screw below the Right PHONO input jack A bad connection at this point will surely be a source of hum and must be corrected Hum will also be heard if the Left and Right Channel plugs are not firmly seated on the PHONO jacks After checking all the conditions stated above if your system hums on PHONO but not on any Line input turn OFF the Preamplifier and reverse the line plug to your turntable Often this will cure the problem As a rule it does not help hum anywhere in the system to ground the Preamplifier to an earth ground such as a water pipe Good grounds like this are hard to find and such a connec tion often makes the situation worse particularly in the case where there is Radio Frequency Interference 8 3 PHONO INPUT PARAMETERS The value of PHONO input resistance R1 R101 may be changed if necessary If the value is decreased less than 47 5 K then C1 C101 will have to be increased to preserve the frequency response If R1 R101 are increased the input capacitors will not have to be changed and the low frequency response will im prove slightly See the Pa
41. was neither designed nor intended WARRANTY FOR FACTORY ASSEMBLED UNITS A factory assembled DH100 is warranted for 3 full years from purchase date including parts labor and normal return ship ping costs to the owner within the continental United States The owner is responsible for shipment to the factory or authoriz ed service facility and must submit a copy of the dated bill of sale when warranty service is requested WARRANTY FOR KIT BUILT UNITS The parts supplied in a DH100 kit are warranted for one full year from the purchase date a defective component is found onacircuit board orinthe kit simply return the individual part to the factory prepaid together with the serial number and the date of purchase It will be replaced at no charge If you cannot locate the cause of a problem in your DH 100K return it to the factory with a copy of the dated bill of sale if in warranty and a money order for 35 Personal checks must first clear VISA and Mastercharge can be processed by phone with your daytime phone number If the difficulty is solely a defective part the unit will be repaired and returned to you prepaid together with the amount of your payment less a charge for packing and shipping If the problem is found to bean error in kit assembly the unit will be put in proper working order and re turned to you prepaid within the continental USA This warranty is void if the kit has not been completely assembled or if oth
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