Tube Amp Archive

Hi all, For the benefit of anyone else who gets a similar problem, I'm pretty sure I found the problem. Basically I've cut the B+ in the wrong place so the screen-grid power-supply capacitor has the correct (scaled) voltage on it, but the actual connection to the screens themselves is still coming o...

Hi Dana, thanks for the quick reply! I did check the voltages before putting the tubes in, and they looked OK, here's what I measured : V+ Vbias 356 -14 <Control MAX> 239 -9 96 -3.2 -56.6 -1.9 -33.1 -1.2 <Control MIN> The dual pot is log taper so 12'oclock is actually getting down to about the 96/3....

Hi all, new to this forum and looking for some technical help with a fixed bias VVR installation. I have a fixed bias VVR2 board from hallamplification, going into a Fender Blues Junior. I'm only scaling the power stage, and all the voltages seem to scale as expected, between 10% and 100% of the v+ ...