Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => AmpTools/Tech Tips => Topic started by: aron on March 07, 2017, 07:29:37 am

Title: Bias pots /trimmers
Post by: aron on March 07, 2017, 07:29:37 am

Hi everyone,I just bought a few things from Hoffman and I have a question about bias pots,I have read that you should use cermet pots cause carbon may burn with DC.Are the fender bias pots cermet? I bought both trims and the larger pots,I'm recapping a traynor bassmaster YBA1A and also I'd like to make the bias adjustable,I have to pick up the package today so will likely start working on the amp tomorrow.
Thanks
Aharon

Title: Re: Bias pots /trimmers
Post by: sluckey on March 07, 2017, 07:59:44 am

Either of the bias pots that Hoffman sells will be fine. A typical bias circuit puts only a small current through the bias pot. I prefer a small chassis mount locking pot but if I ever have to buy a bias pot, I'll use one from Hoffman.

Title: Re: Bias pots /trimmers
Post by: aron on March 07, 2017, 10:37:27 am

Thanks sluckey. :worthy1:
Aharon

Title: Re: Bias pots /trimmers
Post by: PRR on March 07, 2017, 06:10:14 pm

> carbon may burn with DC.

Anything "can" be burned.

I wasn't aware that cermet was better. Except that it can be a little tougher in very small sizes. If you are varying B+ in a helicopter radio, that might matter.

Guitar amp bias is too small to hurt any pot big enough to see.

Title: Re: Bias pots /trimmers
Post by: aron on March 20, 2017, 10:28:40 am

I read too many Weber books.
Aharon