Vista 1 User's Manual
Contents
1. pcLe2 6 l J61 160 0001 100 0006 P 4 9 4k 100R 990 0001 R211 990 0001 C1315 CONN PCB 2 200 0001 cota PCL82 sarong De 200 000 100R 10u 350V 1 f 4 E BE 2000005 100 0001 GEN z SPEAKER RIGHT ROARED te ATRNW TPR RCA RED 100n 250V 1 200 0001 VIA roon2sov R141 ae S 200 0003 porga P 1000006 ik E Saa 3 PHONEJAGK STEREO SW R 990 0001 200 0003 h R ESCH LL 200 0003 R51 J121 Mik J151 Mk Weg 5 sox atid Ln 161 0004 vita 161 0004 Visa KE PHONES 2209 0002 1k Am d 206 0002 206 0002 ATRIAW Y 200 0003 161 0001 t 16 19V L 204 0001 160 0008 PDA lr11 20 1 45v S R151 470k R41 200 0007 NU cia cei cor Lou 470p R91 R101 gt 220u 35V k ba z 220u 36v R221 220u 35v 100 0007 2k2 2k2 T 100 0002 cei gt s10R 2W 100 0002 C101 emsou 100 0002 200 0004 200 000 10u 350V 206 0001 10u 350V 206 0001 100 0001 100 0001 R252 R262 R272 27R 2W gt 27RI2W gt 27RI2W Al R111 206 0002 206 0002 206 0002 100R 200 000d 4 4 We FBK 200 0006 1 6 24 L swi BG ez le 161 0001 Jeep e 100 0003 Wy O i o R172 SW DPDT KEEN 180 0001 202 0002 R162 e 4 4 Kva J42 22k 0 5W CONN PCB 3 202 0002 1 c122 t 2 OPT PRIM LEFT 1n 500V 3 100 0004 160 0003 ol oo ch il d ci Ben R82 P UL T P UL T CONN P B 2 220k 0 5W 100n 250V 202 0001 2 TS 1006906 2020001 G og e E ee e dig OPT SEC LEFT R12 D ee 161 0001 1461 0001 161 0001 161 0001 200 0003 200 0003 160 0004 4 J cel2. that both left and right output transformers are connected identically which will ensure that both channels operate in phase and provide adequate stereo picture If the negative feedback is to be used it is also important that the primary and secondary are connected in phase so please carefully check transformer documentation An oscilloscope is valuable tool if you use old second hand transformers which may not have adequate markings CONNECTING SPEAKERS Speakers impedance should match rated secondary impedance of the output transformer Speakers are connected to terminals J61 right speaker and J62 left speaker SPK R Again for best stereo image they should be connected in phase The second harmonic distortion is common with single ended amplifiers it gives them specific rich sound and air transports sound with some degree of the second harmonic distortion too It is possible to notice change in sound and reduction in distortion just by swapping plus and minus terminals and we encourage you to experiment and find what sounds best for you If you are swapping terminals make sure to do it on both speakers at the same time to preserve stereo image CONNECTING HEADPHONES Headphone output is not a typical feature of a tube amplifier There are technical and commercial reasons it increases manufacturer s cost We wanted to make sure that Model 1 can be used as a headphone amplifier too so the output is there
3. to prevent metal chassis from shorting PCB circuits PCB has a 1 8 hole underneath the sockets Make sure to provide support to the PCB using the holes in addition to the five mounting holes to prevent board flexing and possible damage to the PCB when tubes are inserted or removed You may find it convenient to use chassis mounted sockets in which case there is no stress on the PCB during tubes insertion removal From the chassis mounted socket you can drop wires to the PCB Be sure to use short insulated wires If you mount headphones connector to the bottom of the board left and right channel will swap To bring everything back in order you will need to swap inputs Then your speakers will have left and right channel swapped To rectify that you will need to connect left speaker to the right channel and vice versa Or you can simply use a chassis mounted headphone jack and connect wires to the PCB in the right order When the headphones speakers selector switch is moved to the bottom it will reverse the function headphones position will turn the speakers on and vice versa We do not think this is a major issue but you should be aware If you move volume control potentiometers to the bottom of the PCB the minimum volume position will become maximum It may be cool but it could also be annoying The only solution to the problem is to use chassis mounted potentiometers and bring wires to the PCB If you use chassis
4. 01inch mounting holes and locations of tubes potentiometers switch and headphone connector as well as locations of input jacks This should help builder with designing a fitting enclosure Please always verify dimensions by measuring the actual printed circuit board SPK Rei Ri asi 1 Inc Model 500 0001_r1 L OPT SEC L ect e R233 eur Bis E wise mn ut 12 2 OPT PRI L eae Je Va Ro Faite eg 6 a J1021 Zu Zus LA VI R241 P UL Saisie Fav Du SPK R ERI TS A H Fin ZS e OPT SEC R OPT PRI R Ea i SE JiO11 Zut Ler qa pars cq Sege D W132 3162 2 ew P msee a R392 a 1 9 e engineeringvista com audio K K e e E 1 Ten 0 0 ENG Vista Www Lu N V4 PCLB2 cq ae 1 Di BA rav ke L l 4 V3 PCL82 ker Cu N N Ten e a CONFIGURATION JUMPERS MODE OF OPERATION The Model 1 has four groups of jumpers intended for setting a mode of operation Pentode mode P Ultralinear mode UL and Triode mode T Ultralinear mode can only be used with output transformer that have additional terminal for UL operation a TI SE is gtd Shorting blocks are inserted vertically so that the desired mode of operation is selected The pair of pins on the far right side is not used NOTE
5. 100 hours of operation In normal use upon power up the unit needs to warm up for about 30 minutes for maximum performance The Model 1 kit does not include output transformers or power supply unless it is specifically listed that it does Output transformers and power supply are separately sold ASSEMBLING THE KIT If you purchased an unassembled kit you will have all the parts including tubes and printed circuit board Parts are in marked bags with reference numbers and value written on a bag Reference numbers are the ones printed on the PCB so locating parts positions should be very easy PCB layout printout is also part of this document and you can use it to locate parts Output transformers are purchased separately and not included in the kit First step is to review all the materials received compare to the part list and prepare all tools and a well lit work area Tools that you need are very basic soldering iron tweezers or flat pliers and cutters You will also need solder wire and a digital multimeter If you have an oscilloscope that will help in final testing and experiments but it is not necessary Start assembly with filament configuration jumpers configuring heaters for your specific application Follow with resistors keeping in mind that resistors should be slightly elevated off the PCB 1 32 is sufficient Main reason is that power resistors get warm and this will help air circulation and prevent overheat
6. At any time one of the P UL or T connections must be used CONFIGURATION JUMPERS GRID BYPASS CAPACITOR Jumper J121 122 151 and 152 can be used to bypass G2 on the pentode section The bypass is preferred by some designers it will result in slightly different sound and we decided to have it included as an option In order to engage the bypass the shorting block should be inserted horizontally shorting two lower pins The upper pair of pins is not connected anywhere and can be used to hold shorting block if the bypass is not desired NOTE The grid bypass should only be used with Pentode mode of operation Using it in any other mode will cause damage to the amplifier and or output transformer CONFIGURATION JUMPERS NEGATIVE FEEDBACK SELECTION The Model 1 has optional negative feedback connection provided by jumper J161 J162 FBK FBK e gt Vd By moving the shorting block horizontally across the two lower pins the negative feedback will be engaged The upper two pins are shorting block holders when feedback is not engaged By using negative feedback you will reduce the amplifier s gain increase bandwidth and reduce distortion All the good stuff but harmonic content will change and many people do not have much respect for that kind of sound Again option is available and you need to find an answer for yourself The amount of feedback applied can be modified by changing value of R181 and R182 You will noti
7. C12 C12a C51 C52 100 0006 100n 250V C21 C21a C22 C22a 100 0006 100n 250V C41 C42 C81 C82 C131 C132 100 0001 10u 350V C61 C62 100 0002 220u 35V C71 C72 100 0003 1n 50V C101 C102 100 0001 10u 350V C91 C92 C111 C112 100 0002 220u 35V NOT USED C121 C122 100 0004 1n 500V C141 C142 100 0007 470p 50V J8 160 0005 PHONEJACK STEREO SW J11 160 0001 RCA RED J12 160 0002 RCA WHITE J21 160 0001 RCA RED J22 160 0002 RCA WHITE P11 P12 209 0002 50k audio SWI 180 0001 SW DPDT V1 V2 990 0002 9 PIN MINI SOCKET V3 V4 990 0002 9 PIN MINI SOCKET V1 V2 990 0001 PCL82 V3 V4 990 0001 PCL82 PCB 500 0001 PCB AININ IN IM NT Tj D D IMI MIRIN IN MD OSO ONJO User Manual 500 0001 User Manual 18
8. We were able to take advantage of the amplifiers relatively low output power and came up with a clever way to have the amplifier work at normal power levels with headphones Watts instead of milli Watts and even to push the amplifier to clipping if needed Connecting headphones is fairly straightforward use standard 3 5mm headphone connector J8 and flip the switch SW1 SW1 will engage dummy load across the output transformers and bring signal to the headphones We believe that this is the best way to preserve the original sound of the amplifier wnen headphones are used With headphones which are typically very low power devices the amplifier will operate properly loaded up to maximum output and you can even enjoy the specific sound of tubes soft clipping if you desire this may be very interesting if you intend to use the Model 1 as a guitar amplifier and not disturb anybody Dynamic headphones come in several nominal impedances 16 to 600 Q and you may notice that the maximum sound level is too high or too low You can adapt the Model 1 amplifier to your headphones by changing resistors R281 and R282 The resistors are in series with the headphones and by increasing their value you will increase attenuation VOLUME CONTROL AND AUDIO INPUTS Less expensive stereo potentiometers have poor symmetry between the two parts and we did not want to burden the product with expensive ones so we went with separate volume controls for the left an
9. al 12 bi c12 10u 350V Kap RCA WHITE Weg 100 0001 ls R202 PcLB2 le J62 160 0002 200 0001 1000250 Ra lo R122 R132 Raro Mg R212 990 0001 ous CONN PCB 2 C22a 990 0001 1k 100R No0 R 10u 350V 1 n 200 0003 200 0005 100 0001 z SPEAKER LEFT R22 100n 250V tke 100 000 ee bra st t ROA WHITE si ih MW af EA es 160 0004 RCA n 100n 250V r 200 0001 tke 100n 250V E 1900002 190 0006 200 0003 100 0006 ig rg 200 0003 200 0003 R52 2 a 2 la Pas 163 w J152 WH DE TW i 000 2 Via 1610001 Nita 209 0002 Soa ona R152 Targi TOA 470k A 200 0007 F10 Cu c62 c92 c112 J80 470p 220u 35V l R192 gt 220u 35v k R222 ot 220u 35V va amp NA CONN PCB 2 100 0007 100 0002 c82 2 s10R 2W 100 0002 c102 gt s10R 2W 100 0002 500mA 1 10u 350V 206 0001 10u 350V 206 0001 170 0001 z PLATE 100 0001 100 0001 160 0004 F20 ay v amp AN CONN PCB 2 3A 1 4 LI 4 s L 4 DO 4 2 FILAMENT R182 4k 160 0004 200 0006 c72 3162 1 R310 R320 161 0001 Ton SC R op NOTES 100 0003 OF oe Gei aR 1 Parts with values between asterisks 1k etc are used in the Full Pack assembl y AW 4 2 C91 C92 C111 and C112 are not used a D Si vi KA viza lt visa vpup lt vita K veb K vb K Vida SN AM x NM Cu R330 R340 R350 R360 OR OR KO Ko NIA NIA NA NA R370 Fen WY NA NA BOARD LAYOUT AND DIMENSIONS The following Figure shows the component layout and dimensions of the board in mils 1mil 0 0
10. be connected to that pin although doing opposite will not affect operation as long as filament supply is independent of plate supply CONNECTING OUTPUT TRANSFORMERS For basic model the output transformers should be designed to provide 5kQ primary resistance For the full pack the primary resistance should have 2 5kQ rating Rating of the secondary winding should correspond to the impedance of your speakers 4 8 or 160 typically There are many transformers in the market that have multiple taps to accommodate various combinations Power rating should be minimum 3W for basic and 6W for full pack configuration Model 1 features two pairs of terminals for connecting output transformers The terminals are J41 and J51 for the right channel transformer and J42 J52 for the left channel The terminal blocks for the right channel connections are shown below OPTTSECCR OPT PRI R EI C131 Output transformer s primary winding is connected to the two end terminals of J41 Right side terminal of the J41 as shown on the picture above is connected to Va and the left end is connected to the plate of the pentode part of PCL82 Middle terminal is used for the ultralinear connection if the transformer has the UL tap Left channel transformer is connected the same way using J42 Transformer s secondary winding is connected to J51 J52 for the left channel Terminal with minus sign is connected to the system ground It is important
11. ce variations in the sound but be careful poorly compensated feedback will cause the amplifier to oscillate CONFIGURATION JUMPERS TRIODE PARALLEL CONNECTION Jumpers J171 J172 are used in the Full pack configuration to parallel cathodes of the input triodes when the bypass capacitors C61 C62 are used If you do not need an extra gain this capacitor provides you can safely take it out and then disengage J171 172 too see if you may prefer the new sound HEATER CONFIGURATION JUMPERS Ten zero ohm resistors R290 R380 can be used for different heater configurations The most commonly used configurations are Two tubes Basic configuration V1 and V2 heaters in series Vf 32V If 0 3A use R290 R370 and R380 Four tubes Full pack V1 V4 V1 and V2 heaters in series V3 and V4 heaters in series the two groups of heaters connected in parallel Vf 32V If 0 6A use R290 R370 and R380 V1 and V2 and R310 R340 and R360 for V3 and V4 heaters ECL82 heaters 6 3V connect all heaters in parallel using R290 to R360 CONNECTING POWER As any other vacuum tube amplifier Model 1 needs two voltages for proper operation 1 Plate or Anode voltage Va and 2 Heater or filament voltage Vf Plate voltage should be brought to the terminal block J80 and filament voltage to J90 Picture below shows the layout detail with J80 and J90 Plate voltage Va should have nominal value of 250V acceptable range is 200 270V The
12. d right channel One pair of analog inputs is installed as a standard feature and there is a place for another pair of inputs if you need to connect more than one source The input selector is not required since the source that is not used will not affect the active one If you have both sources working at the same time you will hear a strange mix of the two inputs The gain of the amplifier will change depending on whether or not you decide to use the negative feedback Gain is significantly higher without feedback so you will not need to turn the volume knob that far to get to clipping With the feedback engaged you can do it by moving jumpers on J161 J162 one position down the gain will drop significantly and the volume knob will have to travel further for the same output power UPSIDE DOWN ASSEMBLY The Model 1 printed circuit board PCB was designed with top to bottom symmetry This symmetry enables building a tube amplifier with tube audio look where tubes are mounted on top of the chassis All parts except tube sockets can be mounted on the bottom of the board and soldered on the top side top side is the one with component references in white silkscreen That way the PCB can be mounted close to the top of the chassis and tube sockets can be flush with the top or even slightly higher depending on your preferences There are few things to keep in mind though Top of the PCB should be at least below the chassis
13. eng isla inc Model 1 Experimenter s SE Audio Amplifier User s Manual 500 0001MR4 http audio engineeringvista com Rev 4 Dear Customer We at ENG Vista want to take this opportunity to thank you for purchasing the Model 1 Experimenter s SE Audio Amplifier The people that stand behind your amplifier draw on more than a decade of professional electronics design and manufacturing experience We are committed to providing our customers with the high quality sound at an affordable price We have achieved this goal through modern design quality parts expert components sourcing and efficient manufacturing We are confident that your amplifier will be a pleasure to experiment with and that you will gain a valuable experience When you are ready to move to the next stage in your experimental work the Model 1 will give you many years of listening pleasure as a part of your audio system Before using this amplifier please take the time to carefully read and understand the safety instructions and operating procedures Becoming familiar with all details about your amplifier will ensure safe usage and reliable operation Take special care when operating with high voltages and making adjustments The effort you invest now will be well rewarded as the time goes by THANK YOU ENG Vista Inc YOUR SAFETY IS VERY IMPORTANT TO US PLEASE READ CAREFULLY THE FOLLOWING NOTES AND SAFETY PRECAUTIONS THANK YOU This kit is not intended for be
14. es and exercise caution when powering unit after any change is made If possible gradually rise input voltage and look for any abnormalities smell or smoke tubes overheating excessive glow etc DO P GoObh A O 17 Unplug this product from the wall outlet before making any changes Wait until tubes have cooled down 18 When using replacement parts be sure to use parts with sufficient voltage and power rating and adequate current carrying capability 19 Should it become necessary to replace your tubes remove the AC power plug from the wall and allow thirty minutes for the high voltage capacitors to discharge 20 If you have any questions regarding safe and reliable operation of your amplifier please email us at audio engineeringvista com GETTING STARTED The Model 1 amplifier kit was designed to provide 1 a universal tube amplifier suitable for everyday listening to the music from your PC or portable music source or as a guitar amplifier easy to overdrive 2 a headphone amplifier 3 an amplifier for familiarizing with the sound of Single Ended SE configuration 4 a platform for experimenting with different variations of an SE topology pentode triode or ultralinear operation open loop or negative feedback parallel tubes etc 5 a significant value based on a high performance to price ratio The Model 1 is built on a two sided printed circuit board PCB and uses PCL82 16A8 tubes which are specifically de
15. ginners lt requires familiarity with safe procedures for tests measurements and modifications of high voltage equipment Exercise extreme caution when working with high voltages and always unplug the power before making any changes or adjustments NOTE Please make sure to check our website at http audio engineeringvista com for updates test results and latest news On our website you can also order spare parts Feel free to contact us with any questions or comments We are looking forward to hearing from you SAFETY PRECAUTIONS IMPORTANT SAFEGUARDS PLEASE READ CAREFULLY ALL THE FOLLOWING IMPORTANT SAFEGUARDS THAT ARE APPLICABLE TO YOUR EQUIPMENT SAFETY Read the User s Manual and refer to it frequently during your experimenting Retain the User s Manual for future reference All warnings should be strictly adhered to Follow instructions to the last detail This product should be operated using only the type of power source indicated in this manual Always use an electrical outlet that is grounded If you do not know whether the outlet is grounded consult your electrician or local power company 7 For continued protection against fire hazard replace fuses with the same type and rating of the fuses specified When changing fuses completely remove power from the circuit 8 Power supply cords and all connecting cables or wires should be routed so that they are not likely to be walked on or pinched Pay particula
16. h quality sound reproduction Copyright ENG Vista Inc 2007 17 PARTS LIST Parts with asterisks in the VALUE column are used in the Full Pack assembly Item Qty Reference 1 2 R41 R42 A R11 R12 R51 R52 R121 R122 R141 R142 R181 R182 R231 R232 R241 R242 200 0003 1k R21 R22 R61 R62 R201 R202 R391 R392 200 0003 1k R71 R72 202 0001 220k 0 5W R81 R82 202 0001 220k 0 5W R91 R92 200 0004 2k2 R101 R102 200 0004 2k2 R111 R112 R131 R132 200 0005 100R R151 R152 200 0007 470k R161 R162 202 0002 22k 0 5W R171 R172 202 0002 22k 0 5W R191 R192 206 0001 510R 2W R211 R212 200 0005 100R NIM IM IN IN D BRIN IN NO Nh 0 R221 R222 206 0001 510R 2W R251 R252 R261 R262 R271 R272206 0002 27R 2W R281 R282 204 0002 39R 1W R290 R370 R380 N A OR R300 R310 R320 R330 R340 R350 R360 N A F10 170 0001 F20 170 0002 3A J101 J102 J111 J112 J121 J122 J161 J162 161 0001 JUMPER 2X2 J131 J132 J141 J142 J151 J152 J171 J172 161 0001 JUMPER 2X2 D J101 J102 J121 J122 J161 J162 161 0002 SHORTING BLOCK 0 1 J131 J132 J151 J152 J171 J172 161 0002 SHORTING BLOCK 0 1 J41 J42 160 0003 CONN PCB 3 J51 J52 J61 J62 J80 J90 160 0004 CONN PCB 2 C11 C11a
17. ing Also some resistors have circuit connections underneath and there is a possibility of malfunction if the resistor body touches exposed trace This is not very likely since the PCB connections are protected by a solder mask and resistors have durable coating However this could be a matter of safety and also troubleshooting of such problems is really difficult so it is better to spend some extra time up front to come up with great assembly After resistors install 2x2 headers for mode selection Pentode Triode Ultralinear FBK etc Next step is assembly of all capacitors Make sure to follow polarity directions for electrolytic capacitors All electrolytics have markings designating leads to be connected to the negative voltage Model 1 printed circuit board has a plus sign for the positive terminal of an electrolytic capacitor Positive terminal on the PCB also has a square pad around the hole for easier identification on the bottom of the board After capacitors are installed you can proceed with connectors and finally with tube sockets and volume control potentiometers Once everything is installed take a short break and then come back and carefully inspect your work Check component locations and proper orientation of electrolytic capacitors Inspect all solder joints and make sure there are no solder bridges or splashes on the board All joints should look clean and shiny If you are not sure that a solder joint look right
18. mounted parts input jacks headphone connector switch and volume control make sure to use short coaxial cables to minimize noise pickup and stray capacitances that may cause amplifier to oscillate FINAL WORDS Once again thank you for your purchase We hope that the Model 1 will give you hours and hours of fun and have you experience a multitude of different qualities of the tube sound Once you have exhausted all of the options we hope that you will retire the amplifier from your bench into a nice chassis and have it rest on your work desk or in the bedroom accompanied by a PC or an MP3 player of some kind Once all experiments are finished make sure to permanently short selected jumpers one way is to bend the pins and solder them together in order to prevent deterioration of contacts over time Robust design should provide you with years of pleasant sounds with only maintenance being change of tubes once the original ones are too weak to rumble Our design is really gentle with the tubes so they should last much longer than tubes in some other designs that try to pull the last milliWatt out of them Finally we want to remind you once again to take extreme caution while working with high voltages If you are not thoroughly familiar with the safety procedures feel free to enlist help of a relative or friend There are many very knowledgeable people in this field and they all share passion for spreading the art and science of hig
19. power source should be able to provide 80 100mA for basic configuration and 160 200mA for the full pack Sound is significantly affected by the power supply quality so make sure to have sufficient filtering PCL82 tubes are designed for series connection of their filaments so they require current source as opposed to some other tubes that require voltage source for filament supply Heater specification for this tube is 0 3Amp and 16V Rugged construction of the tube s heater allows that it is powered from the voltage source as well but you can expect high current surge and bright yellow heater in the first few seconds of operation In theory this reduces life of the heater but these tubes are very rugged and will have long life even in this less than perfect situation Basic version of the Model 1 amplifier has the two heaters connected in series so the filament supply needs to be able to provide 32V at 0 3A Resistors R290 380 are placeholders for jumpers which allow for different heater configurations ECL82 tubes which are PCL82 equivalents with 6V heaters can also be used by configuring all heaters in parallel R290 to R360 installed R370 380 left out For more details refer to the description of the heater configuration jumpers above Filament voltage can be DC or AC so there are no polarity markings on J90 If the DC is used left pin is the system ground see the Figure above so the negative polarity of the filament voltage can
20. r attention to cords and cables at plugs receptacles and terminal blocks Always use wires with adequate ratings and safety certifications CE UL etc 9 During operation the tubes get very hot Do not touch the tubes since this may result in a severe burn Allow several minutes after removing power for tubes to cool down before touching them 10 Turn off the unit as soon as you stop actively using it Unplug the power supply from the wall during a lightning storm or when the product is to be left unattended and unused for longer periods of time 11 Do not use this product near water or in wet areas Damp basements should be avoided 12 The product should be placed away from heat sources such as radiators heaters stoves or other appliances that produce heat Also avoid putting the unit in the direct rays of the Sun 13 Proper ventilation is crucial for safe and reliable operation Never place anything on top of your amplifier that could obstruct airflow and cause the parts to overheat and damage the amplifier Do not place your amplifier in a rack or bookcase unless proper ventilation is provided 14 Care should be taken to prevent objects from falling and liquids from spilling into the unit Do not subject the unit to excessive smoke dust vibration or shock 15 During experimenting make sure that all jumpers are properly seated in the correct position that there are no foreign objects or solder bridges 16 Always wear protective glass
21. signed for audio applications If you bought assembled kit rest assured that all amplifiers go through rigorous testing and extended burn in before being shipped so you are guaranteed to receive high quality product There are two versions of the Model 1 amplifier kit 1 BASIC this amplifier will output 2 2 5W per channel in pentode mode depending on the output transformer selected and comes with single stereo input and one pair of tubes It is best suited as a headphone amplifier or PC amplifier An upgrade kit is available for conversion to the FULL PACK version 2 FULL PACK this version has maximum output power of 4 5W depending on the output transformer has two stereo inputs and two pairs of tubes the two tubes per channel are connected in parallel It is best suited for listening in small rooms and as an instrument amplifier Due to the relatively low power the Model 1 works best with efficient speakers SPL above 90dBm As every other SE amplifier the Model 1 has a low damping factor it will perform best with single driver Hi Fi speakers or alternatively two way speakers with simple crossovers The standard unit is delivered as an unassembled kit or tested and burned in basic assembly Vacuum tubes are delivered separately in original boxes for maximum protection The tubes need to be inserted and firmly seated in their sockets before the power is delivered to the unit The optimum sound reproduction will occur after 50
22. ssist you in your experiments Please note that the schematics is considered a copyrighted work and a trade secret However as a purchaser of our product you are granted a license for unlimited modifications The only thing we ask for is that this schematics is not reprinted for public use or commercially used without getting appropriate license from ENG Vista Inc R171 22k10 5W 202 0002 an measurements at Va 250V T T R161 7 t T Kva Jai CONN PCB 3 SEN o z OPT PRIM RIGHT 1n 500V 3 100 0004 I 160 0003 R81 ea gt len Eu t J51 cita See 220K0 sw P UL mn p JuL T R ss 100n 250V 202 0001 202 0001 N R231 R241 z TS 100 008 101 Ke Am Q Sg Jm Q Jai Gl fi nr OPT SEC RIGHT W b 161 0001 161 0001 t 1161 0001 161 0001 200 0003 Los og 160 0004 R1 S Cu a zl ye ln ae al su C 10u 350V ai vip vaB ROARED ik 100n 250V 100 0001 V3A 95 110V R121 R131 Ze Roo
23. touch it with a hot soldering iron again until it looks right Cold solder joints may create problems few hours days months down the road and are extremely difficult to troubleshoot Then plug in the tubes connect the output transformers and speakers or dummy loads and proceed with slowly powering up the unit Bring the power for the filaments Vf first and make sure that all the tubes have about 16V on their heater pins depending on your supply it may take up to a minute for this voltage to stabilize You should be able to see nice yellow orange glow from the heaters Tubes that you received are already burned in so you can continue by bringing anode voltage Va and measuring the most important in circuit voltages refer to the schematics section for test points and voltage levels If you followed all the instructions everything should go smoothly and now you can connect some music source to the inputs and start enjoying fruits of your hard work But for now keep reading the instructions CONNECTIONS NOTE Before you turn the amplifier on make sure the speaker connections are properly hooked up or that headphone selector switch is in the headphone position Never run the amplifier without speakers or headphones since this may damage transformers When turning the unit on make sure the volume control is at its lowest setting ELECTRICAL SCHEMATICS The complete electrical schematics with component values is given to a
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