DIY Push-Pull (PP) 6V6 Tube Amplifier Schematic
Brad S.  
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DIY Push-Pull (PP) 6V6 / 6V6GT Tube Amplifier with Hammond Transformers
This 6V6 amp was built following the push-pull (PP) EL84 / 6V6 Dynaco A-410 output transformer schematic. There are a few minor deviations from the original schematics. Instead of Dynaco transformers, Hammond 1608A audio output transformers and a Hammond 272HX power transformer were used. The EL84 / 6V6 PP Dynaco A-410 output transformer schematic showed a 1000 ohm feedback resistor which resulted in bad amplifier oscillation. Feedback resistor Values between about 6 and 10 k-ohm worked well and I settled on 10k. A 5Y3 rectifier would have been to small for a stereo amp so a JJ GZ34 rectifier was used. It became necessary to put a 100 ohm resistor before the first power supply capacitor to bring down the B+ to about 325 volts as I was getting in excess of 345 volts (there is less voltage drop through a GZ34 versus a 5Y3).
I am planning to replace the 100 ohm, 10 watt power supply resistors with 20 watt resistors. The 10 watt resistors run a little to hot for my taste.
6SL7 driver / Push-Pull (PP) 6V6 / 6V6GT Tube Amplifier Schematic
The driver tubes are Tung-Sol 6SL7GT and the output tubes are EH 6V6GT. The amplifier really sounds wonderful with nice detail and plenty of bass response. Power output is about 10 watts per channel.
DIY Push-Pull (PP) 6V6 / 6V6GT Valve Amplifier with Hammond Transformers