ampage Tube Amps / Music Electronics	For current discussions, please visit Music Electronics Forum.

ampage archive

Vintage threads from the first ten years

silverface 100W twin bias question

4/5/2005 5:24 PM
Jason	silverface 100W twin bias question Hey everyone, I'm pretty new with tube amp work so please forgive me if this has been asked before... I just don't really get the bias circuit in this silverface twin amp I'm working on. It's one of the ones with the fender bias pot in it. When I try and get around 34ma for each output tube, I can only get it in a pair. What I mean is, when I set the 1st tube to 34ma, I'll get 34ma on the next one, and then only 12ma on the other two. I tried to equal them out with the pot, but I can't get anywhere close to equal bias for the pairs....what's going on here?? FYI:I'm using a weberVST bias probe, and I'm getting good voltage. Thanks, -Jason

4/5/2005 5:24 PM

Jason

silverface 100W twin bias question

Hey everyone,

I'm pretty new with tube amp work so please forgive me if this has been asked before...

I just don't really get the bias circuit in this silverface twin amp I'm working on. It's one of the ones with the fender bias pot in it. When I try and get around 34ma for each output tube, I can only get it in a pair.

What I mean is, when I set the 1st tube to 34ma, I'll get 34ma on the next one, and then only 12ma on the other two. I tried to equal them out with the pot, but I can't get anywhere close to equal bias for the pairs....what's going on here??

FYI:I'm using a weberVST bias probe, and I'm getting good voltage.

Thanks,
-Jason

Replies:

jason Sorry...after reading that, I wante... -- 4/5/2005 5:31 PM