Rick Tone Trem-O- Drive

[Stymie]

I built the Trem-O-Drive as shown on the Rick Tone schematic with the exception of the two switches.  I replaced the drive and tremolo toggle switches with a foot switch for each.  The schematic below shows the wiring for these switches.

I also had to install a pull down resistor to eliminate popping when the drive foot switch disengages the drive circuit.

There is a low level thumping when the tremolo is on.  The thumping volume increases or decreases as the depth pot changes.  It also does this to a lesser degree with the speed pot.  The thumping is not audible when playing my guitar but is noticeable when the guitar is silent.

Is there a solution I can use to eliminate the thumping or is this just something I have to live with?

[Williamblake]

When i played with that tremolo circuit I put 100nF from the oscillator‘s plate to ground. You could change the resistor between the cathode and the intensity pot to shift the tremsignal to a different bias range. Never tried the resistor but the cap helped.