degeneration

[surfsup]

I see you are focusing on "C". I gave "A" a shot this morning on my Ax84 HO (dirty non-clean) amp with EL34 single ended cathode biased at (if memory serves) ~80mA with a 100R resistor. I get 14.5V at the cathode, again from memory, and the plate sits at ~260V. I clipped a lead on the plate pin3, and on the cathode ground at the buss and put the C/R between the leads with the C nearer the plate.

I tried about 8 different combos of R/C I'm pretty sure this list is right:

Resistors:
3300
4700
5600

Caps:
0.0022
0.0047
0.01
0.022
0.047
0.15

In the end, the 3300/0.0022 and 3300/0.15 sounded best to me. However, I then took the RC filter off. Although there was a slightly more raw tone, the amp was brighter and more lively. The RC filter seemed to muffle the amp enough to hear it. I am now not even bothering with it.

[Andy Le Blanc]

Ive seen "A" as a conjunctive filter I think in a blues expess plus pdf

I guess if the amp needed to be corrected that way it would be useful

another tool to use... was the self bias bypassed?

mine is a combo bias, been fiddling with "C", I was surprised at the apparent
increase in volume. The cathode resistors are un bypassed, I expected the opposite.

more like focus maybe...

[surfsup]

It was still biased with the same rc combo on the cathode. I guess i should try it again and remove the Ck leaving just the Rk.