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

ampage archive

Vintage threads from the first ten years

Search for:  Mode:  

variable bias? what's that and how to make?

6/16/2000 2:37 PM
variable bias? what's that and how to make?
someone recently advised me to replace the bias inside my vintage MARS tube amp (24 yrs old) with a variable bias...  
what's that?  
Is that easy to make? what are the pros and cons?
And now, a word from our sponsors:

6/16/2000 2:58 PM

Basically you would be replacing a fixed resistor in the bias supply with a potentiometer to adjust the negative voltage to your power tube grids. This is just an easier way to service the amp when retubing.  
There is no performance increase........ just convenience :>)  
Look at the transition in some fender blackface amps from fixed resistor to potentiometer. that should get you steered in the right direction.  

  Page 1 of 1