PRS HDRX-20 Bias Question

[Paul_g]

Hi All, new to PRS amps, not new to tube amps. If I purchase a brand new matched set of TungSol 5881 power tubes (same kind the amp ships with), do I have to re-bias the amp?

 

[Stephen J.]

You should at least check the readings to see if you need to make adjustments.

 

[RickP]

Hi All, new to PRS amps, not new to tube amps. If I purchase a brand new matched set of TungSol 5881 power tubes (same kind the amp ships with), do I have to re-bias the amp?

The likelihood is that they are close enough to go, and they certainly won’t damage your amp without the adjustment. That said, there are always differences in tubes, even matched sets and it’s best to check and adjust with a new set. PRS amps make that easier than most (such as the Carol Ann “AutoMon” amps) by putting the contacts where you can get to them. Just a meter and screwdriver to adjust.