Tube Amp Archive

Martin, Yes, I was measuring the right pins, and yes, there was a wiring error. I am embarrassed that I didn't find it, especially since I checked over the wiring before my last post. The funny thing is, the error was made by the monkey that came before me, and not only didn't I find it, I assumed i...

Thanks much for all of these replies! I tried to measure the voltages as you have suggested, but I'm not sure these readings look right On the cathodes, I can't really measure any voltage WRT GND...0.00 - 0.02 volts. But the grids are another story. One V4 [brown] I get a very small DC voltage WRT G...

try try again

meant to add the schematic as an attachment

Hi, I have an older [octal] Gibson GA-20 amp with an odd problem. I hope one of you can help me with some ideas. The amp was in terrible shape when I got it, and a lot has been replaced and I have cleaned it up pretty thoroughly. I can hear the amp has a good sound in it, but layered over the top it...