Randall RD45 oscillating

[Zouto]

Hi, I got an oscillating Randall RD45 on the bench. Clean channel is ok, when activating Boost in Gain channel, V2 is oscillating in higher gain settings. Swapping tubes ( V1, V2) did not help. Unfortunately I could not get a schematic, Randall refuses to hand out any schematics.
I'll try to fix it with a snubber cap (100pF) across V2's plate resistor(s), but maybe there's some better cure?
Thanks for help and informations,
Zouto

[mozwell]

Not sure how close this is, but attached is the sch for the RD50

[Zouto]

Thanks a lot, there are some differences in design, fixed bias in RD45 vs. cathode bias in RD50 etc., but it helps. Double sided pcbs are are drag to trace. I'm still trying to get the right schematics.
Zouto

[g1]

schematic attached

[Helmholtz]

What is the frequency of the oscillation?

Oscillation can be caused by a filter cap having increased ESR or low capacitance (e.g. C28).

[g1]

What is the frequency of the oscillation?

Oscillation can be caused by a filter cap having increased ESR or low capacitance (e.g. C28).

This is a very old thread, I just wanted to attach the schematic. I assume the amp will have been fixed by now.