Tube Amp Archive

Measure the volatage at the junction of the PI coupling cap, 220k and 1k5 grid stopper resistor to see if it is the same on both sides. I think it is likely that there is a high voltage leaking into one grid circuit from somewhere. Since you are observing this on two amps, is the problem on the sam...

When u state that it is either cathode or fixed what does that entail? Does it mean that when not in cathode bias mode that the cathode resistor is bypassed completely? Or does it render negative voltage assist only? Some current prod cathode bias amps are IMO very optimistic in their cathode resist...