Allen Old Flame bias question/biasing in general

[MikeNiteRail]

So my newly acquired Old Flame head reads that I should bias the amp between 30mA-35mA. What are the dangers in biasing an amp like this under suggested mA?

I had a Bassman RI LTD that I used for harmonica. I had that amp biased really cold 18-20mA to tame feedback and add crunch with JJ 6L6 tubes. I really preferred that sound. Maybe that was only ok to do since it was a 4x10 and a different impedance??? Since the Old Flame is so easy to bias, I thought I might try it with a harp friendly, cool bias with the JJs.

Thanks!

Mike

[alltone]

I would think there should be no danger in under bias..just potential problems with over bias when tubes draw more current then they can handle which will shorten their life.

[GearHeadFred]

Technically, when you are drawing LESS idle current (MA), you are OVER BIASED. No harm at all in that. In fact, you will increase tube life.

[phsyconoodler]

It's better to use a V1 premp tube with less gain than cold-bias the amp.Use a 12AU7 or 12AY7 instead of colder bias for harp.

[Blue Strat]

It's better to use a V1 premp tube with less gain than cold-bias the amp.Use a 12AU7 or 12AY7 instead of colder bias for harp.


Why is that "better"? The only thing that's "better" is what sounds better to the user (as long as it's safe, and biasing cold IS safe).

But yes, it is recommended to try lower gain preamp tubes. This is what most harp players do.

[alltone]

Technically, when you are drawing LESS idle current (MA), you are OVER BIASED. No harm at all in that. In fact, you will increase tube life.
:rolleyes: I stand corrected. Doug