Tube Amp Archive

I built a 100 watt (2x6550) bass amp. I am running 680 volts on the plates and 430 volts on the screens. I used 1k5 5w screen resistors. I have been using the amp weekly (left at practice space) for 3-4 hour session practices with no problem. 6 months and going strong. I am using the Tungsol RI 6550...

+1 for http://www.classictone.net/40-18006.html I just put one in a 1966 Bandmaster myself. It had exactly the same problems as you are describing. Horrible distortion with either channel volume > 3. +1 for the 1 ohm resistors. Makes checking bias much easier. What I also did when I converted to a 3...