Tks Jeff. Yes and no. I do have the same promblem as yours before. One tube couldn't bias but mine was one of the tube is damaged. What demaged the tube could be as what you said. After changing it the amp works fine but the extreme right(#4)tube that I replaced was the most unstable one(not haunting but reading changed everytime I on the amp, the rest were around 0.470v but this one quite often diff from the rest).
What I'm having now is the bias haunting. All 4 of them. I got someone told me it's either the feedback loop got problem or the tubes are not well. I doubt so is the latter.
What I'm having now is the bias haunting. All 4 of them. I got someone told me it's either the feedback loop got problem or the tubes are not well. I doubt so is the latter.