Adding intensity / depth to a GA-5T tremolo circuit

[hearforever]

I have a question about adding an intensity / depth control to a Gibson GA-5T type circuit. this is a similar or identical circuit to the Gibson GA-1-RT amplifier

http://music-electronics-forum.com/a...-schematic.pdf

Is it possible to add this control easily to this circuit?
Thanks!

[Enzo]

Comes to mind:

see where the 0.1uf cap comes from the trem circuit and arrives at the junction of the two 220k resistors at the grid of the power tube? Replace those two resistors with a 470k or 500k pot, and wire the cap to the pot wiper. That ought to make it variable.

[hearforever]

That's what I thought. Basically the triode tremolo section is modulating the signal headed to the power tube to ground, right? So the pot would adjust the amount of signal being modulated. I would think in that case when the pot is turned clockwise it would be increasing the intensity.

Just noticed this Magnatone circuit is similar but has a more complicated variable intensity. Why are there .02 coupling caps on either side of the pot there?
http://www.prowessamplifiers.com/sch...natone_410.pdf

Anyway, I think I'll try switching the resistors for the pot.
thanks

[Enzo]

The way I would explain it is that the trem oscillator is sending out a large voltage low frequency waveform, and that waveform is changing the power tube bias moment to moment, thus affecting the stage gain. But I am open to better explanations.

[Enzo]

In the magnetone, one cap blocks the DC plate voltage from the trem tube plate, and the wiper cap blocks the DC voltage from the 12DW7 cathode circuit.