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10 Watt Vacuum Tube Amplifier
Description:
This ten watt vacuum tube amplifier has a flat response from 30 Hz up to 27Khz and has the depth and warmth of amplifiers that were used in the 1950’s. Since high voltages are required, it is suggested that only qualified technicians and individuals build this amplifier.

How it Works:
It produces 10 watts peak and 5 watts RMS of output power. Special attention was paid to the development of the 6AN8 preamp circuit so that it would produce maximum gain and thus eliminate the need for yet other tubes. Also, the AC voltage to the filament of the 6AN8 was rectified to DC to eliminate 60HZ hum. With no input, this amplifier is very quiet. Oversized DC filter capacitors along with a 10HY choke ensure a DC supply with minimal 60 HZ hum. A low pass filter at the input to the grid of the preamp along with grid blocking resistors on the 6V6’s prevent RF signals from entering this circuit and causing problems. Check for two volts across the 33 ohm resistor to ensure that about 61 mA is flowing to all circuits. Regarding gain; the output from most electric guitars is around 200 mV RMS which will drive this amplifier to full output, as will the output of most tuners. The addition of small screw in rubber feet will raise the chasis and allow for better ventilation. Also, the extra rectifier in the 6AN8 fillament circuit is just to reduce the voltage by .7V.
Power Transformer = Hammond 269EX 380 V ct @ 65 mA / 6.3V @ 2.5A
Choke = Hammond 157J 10HY @ 65mA
Output transformer = Fender P-TF22913 12 W 8000 ohms ct . to 8 ohms
Chasis = Bud AC-406 7” by 9” by 2” high
120 volt fuse = 2 Amp
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