Adding Tremolo/Vibrato to an Amp

[jon]

I was thinking about building a Dr. Z Prescription (schematic attached) but adding tremolo/vibrato to the circuit. I was hoping to avoid the standard bias modulating circuits and go with something from say a brown Showman (schematic attached). I think I have figured almost everything out with the tremolo circuit its self but I am a little confused about dumping the signal back into the PI and injecting the signal into the tremolo circuit.

On the Fender circuit they use a very small coupling capacitor on the input of the PI (.0005uF) the Z uses an .022uF with a voltage divider of 1.2M and 100K.

Should I just take the signal from the voltage divider and dump that into the tremolo and use the standard Fender coupling cap to feed the output into the PI? or should I change things.

If there is another circuit someone suggest that would also be appreciated.

[tubeswell]

There's a chapter in the Darr book that has a little bit on other tremolo circuits. Meanwhile, I am waiting patiently for Merlin to write his book on designing tremolo and reverb circuits for tube guitar amps.

Otherwise go with the fender design in the first instance, and then tweak.

[jon]

Anyone???

[tictac]

The problem with the brown/blonde Fender vibrato circuit is it does color your tone even when not in use. You could switch it in and out with a relay or switch, bypassing the circuit entirely when not in use.

It is a cool sounding circuit but it adds another 3 12AX7's to the tube count. You can use a 6AT6 for the single triode in the circuit.