Ampeg J-12T RI red plating

[The Dude]

Gotcha, it's wiggling the ground reference --
Current is now 31mA/tube.
Dude has had this amp for a while, presumably with no issues.

I'll take a closer look at the trem section in the morning, may wanna tame it anyhow as I recall higher settings sounding choppy/nasty..

Don't be afraid to bump the cathode resistor a bit more and wrangle the bias to 25mA or less. Maybe the previous owner had no issues because the previous tubes were more robust. Or, maybe the amp was red plating and he didn't notice.

[hylaphone]

Well, I bumped up the cathode resistor to 250R and the EL84's are now idling around 25mA -
Also raised R8 and R34 for less bias wiggle - the tremolo is a lot more useable now and the tubes are stable with no signs of red plating.

I'm flabbergasted how far we had to take this, and how the amp even functioned as long as it did before cooling down the bias.
Anyhow, thanks a lot for all the help!