Biasing an Express

[sliberty]

So I have installed the 1ohm resistors and banana plugs on my Express for measuring idle current (voltage converted to current of course), along with a multi-turn trim pot for adjustments. But I am really new at biasing. All of my prior builds have been cathode biased amps, and I have done nothing to adjust from the standard values. So I need some guidance.

What are the acceptable ranges for idle current for EL34's and for 6V6's in an Express given the B+ it uses? And what are your favorite bias settings for these tubes? I know that favorites will vaary a lot and should be judged by ear, but it will give me something to start with.

Thanks,
Steve

[Normster]

I avoid math as much as possible, but I always do the calcs for bias. For example (assuming 400V on the plates) an EL34 is 25 (watts)/ 400 (volts) X 70% (dissipation) = 43.75 mA. 6V6 is 14 / 400 X 70% = 24.5 mA.

As for the minimum and maximum dissipation, I'm not sure. I typically use 70% because it seems to work.

[MooreCowbelle]

And make sure you actually measure the plate voltage...

[Allynmey]

Steve, KF just set -30V on the grids and left it there I understand.

Allyn