Stereo 80
Vacuum Tube Amplifier
Owner's Manual
Stereo 80 Vacuum Tube Power Amplifier
OFF
ON
BIAS DISPLAY
TRIODE
ULTRALINEAR
POWER ON
POWER OFF
R
STEREO 80
Vacuum Tube Power Amplifier
V3
V4
V7
V8
LEFT CHANNEL
RIGHT CHANNEL
OUTPUT TUBE BIAS ADJUSTMENT
Page 1: ...lifier Owner s Manual Stereo 80 Vacuum Tube Power Amplifier OFF ON BIAS DISPLAY TRIODE ULTRALINEAR POWER ON POWER OFF R STEREO 80 Vacuum Tube Power Amplifier V3 V4 V7 V8 LEFT CHANNEL RIGHT CHANNEL OUT...
Page 2: ...ear Modes 7 Bias Adjustments general 8 Output Tube Bias Adjustment Procedure 9 Burn In Procedure for New Output Tubes 10 Tube Replacement 11 Alternate Tube Types 13 Minimizing Noise in the System 14 W...
Page 3: ...riode or Ultralinear mode Switching between the two is easily done via a front panel switch State of the art biasing circuitry allows you to easily attain precision bias settings for each of the outpu...
Page 4: ...Panel Inputs and Outputs Inputs There are two input jacks located on the rear panel of the amplifier labeled Left and Right These connect to your preamplifier Line Outputs Never plug in or disconnect...
Page 5: ...lows you to connect audio components such as CD players directly to the Stereo 80 without using a preamplifier if desired Most power amplifiers have input sensitivities in the range of 1 to 1 5 volts...
Page 6: ...period a low or high AC line voltage condition may be indicated The AC line voltage varies from country to country city to city house to house and even the time of day in many locations It can also be...
Page 7: ...e amplifier in Triode mode reduces the amplifier output power to about 1 2 of that in Ultralinear mode Triode mode also softens the clipping characteristics of the amplifier so it seems to need less o...
Page 8: ...should be turned on for 15 minutes prior to bias adjustments Letting it idle for a full hour so that all components come up to full thermal equalization is also a good idea but not usually required No...
Page 9: ...kwise as this makes the bias setting even higher If an output tube bias indicator lamp cannot be adjusted for both green and red the associated output tube is probably faulty Adjusting the potentiomet...
Page 10: ...r is turned fully counter clockwise Note If an output tube indicator lamp cannot be adjusted for both green and red the associated output tube is probably faulty 4 Adjust the bias potentiometer for ea...
Page 11: ...is do not operate vacuum tube equipment on top of vibrating surfaces such as loudspeakers But if a tube is so sensitive that just having the amplifier turned on causes the microphonic sounds the tube...
Page 12: ...de 3 000 to 4 000 hours of use before they have to be replaced Some audiophiles replace them after as little as 1000 hours of use to keep the amplifier in top form It is not uncommon however for an ou...
Page 13: ...with alternate part numbers without informing their customers first Some audiophiles feel strongly about which manufacturer and or particular version of vacuum tube to use for specific applications T...
Page 14: ...ust plugging the preamplifier s power cable into a three prong AC outlet However if the AC outlet itself does not provide a really good ground the power cable can be plugged into a three to two prong...
Page 15: ...as been removed or defaced This warranty gives you specific legal rights and you may also have other rights which vary from state to state If service is required contact the dealer from whom you purch...
Page 16: ...points INPUT SENSITIVITY 3V for full power output Input Sensitivity Control set to maximum INPUT IMPEDANCE 50k SLEW RATE 30V S SIGNAL TO NOISE RATIO 90db below full output TUBE COMPLEMENT two 12AT7 t...
Page 17: ...04K R7 12 7K 5W 2 5W C103 C105B C102 R119 R109 R104 R101 2M 47uF 22uF 2 0K 100pF 400v 1 2 12AT7 49 8 7 6 3 2 1 1M V5 630V R110 1 2 3 9 301 R102 301 R103 301 R105 301 R112 27K 3W 301 R111 6 7 8 C104 2...
Page 18: ...219 5 2 ohms 3W 56uF C216 400V 56uF C217 400V 100V 100V VIO VIO D7 D8 C226 470uF 35V 1M 1W R217 264K R218 10uF C227 250V U1 7812 O G I D2 D4 D1 D6 470uF C211 35V 022F C212 C213 10uF 9 9 ZD3 200V 5W ZD...
Page 19: ...47F 11 13 12 8 9 10 1 4 1 4 1 4 1 4 4 1 6 5 2 3 LM339 U4 160V 160V Y3 12V Y4 Y7 Y8 GND R63 20 5K 127 R64 127 R65 17 4K R66 74mV 87mV R55 1 1K R56 R57 R58 1 1K 1 1K 1 1K BIAS ADJUST PC BOARD MOUNTED TO...
Page 20: ...metal oxide R208 11K 3W metal oxide R13 113 27K 3W metal oxide R12 112 30K 3W metal oxide R14 114 2 ohm 5W metal oxide R20 21 120 121 47K 5W metal oxide R202 203 204 205 206 207 Dual Potentiometer 50K...
Page 21: ...be Socket 8 pin PCB mount for V3 4 7 8 Switch DPST AC Power SW1 Switch SPDT Triode Ultralinear SW2 Switch SPST Bias Lamps SW3 Relay 12V DPDT K1 2 Ferrite Beads FB1 through FB8 Choke 32 henry 360ma L1...
