Qn about Epiphone EA33RVT output stage grid leak R

[tubeswell]

Hi Y'all

I noticed that this amp (and a few others as well) have a resistor (in this case "R25" - 330k) between the bottom of the grid leak resistors for the output stage and the ground. What is the reason for this extra resistor here? And how critical is it?

Thanks

http://www.schematicheaven.com/gibso...vt-galaxie.pdf

[Steve Conner]

That resistor sets the DC conditions for the bias-wiggle tremolo. The trem waveform is injected through C13, and if it weren't for R25, the DC charge on that cap would be undefined.

It's only critical in so far as it'll affect the amount of tremolo you'll get, and if you make it too big, the power tubes may run away.

[tubeswell]

That resistor sets the DC conditions for the bias-wiggle tremolo. The trem waveform is injected through C13, and if it weren't for R25, the DC charge on that cap would be undefined.

It's only critical in so far as it'll affect the amount of tremolo you'll get, and if you make it too big, the power tubes may run away.

Ah - so it forms a voltage divider with R34 in this circuit then? (which bleeds excessive current from C13?)