[Harp-L] Tube Bias

[Mike Best <mike.d.best@xxxxxx>]

Excuse me for straying from the very entertaining philosophical debates
which are currently taking place on harp-l, but here's a query of a much
more mundane, technical nature.

 

My two main tube amps are both Fenders, a 1990 Blues Deluxe and a 2000
Bassman RI.  Both have had a bias pot installed.  I've also got a pair of
bias probes which I can use to measure the current in the power tubes (I
think that's the right terminology, I'm not very technical)

 

Anyway my question is, what current should I bias the power tubes for?  The
info which came with the bias probe says that 6L6 power tubes should be
biased for 30-45mA, but Fender amps shouldn't go above 35mA.  Does that
sound right? Does the bias affect the sound of the amp?   Any advice would
be much appreciated

 

Cheers, Mike