Question about phase shift oscilator/tremolo

[überfuzz]

I have a home brewed amp with a bias modulating tremolo, the oscillator is the Fender take on a phase shift oscillator. When I engage the tremolo there's a popping sound. It's not LOAD, more kind of evident. Is this a normal thing in these tremolo circuits and if so, is there a quick fix?

Thanks!

[Chuck H]

Fender probably has probably used a dozen slightly different oscillator circuits. AFAIK none should pop audibly when engaged or disengaged. That doesn't mean they don't, but I don't recall a truly objectionable one. If you have grounds daisy chained that may cause it. Or if you have the switch implemented differently than I'm familiar with. Can you post a schem?

[Enzo]

There is a popping sound as in it pops when you stomp the switch? Or there is a popping sound as in it goes pop-pop-pop-pop... along with the trem pulses?

[loudthud]

Many Fender oscillators employ some kind of kick starter. This usually takes the form of some DC applied to the footswitch so that when you hit the switch, the oscillator starts immediately. Depending on the exact circuit, the kick start pulse might feed through to the output of the oscillator. From that point, an imbalance in the output tubes or the phase inverter might allow the pulse to cause a pop at the speaker. The devil is in the details so please post a schematic.

Afterthought: A Concertina PI might act oddly with a bias wiggle tremolo.