The switch pop saga continues ... this is a new one.

[midwayfair]

I've been switching to optical bypass and buffered bypass on a bunch of stuff in the hopes of killing switch pops completely.

But today I encountered something completely new: a switch popping with buffered bypass. while unplugged. with the buffer FET removed. and the op amp removed. and the guitar unplugged. Literally every source of DC disconnected, even charged caps or line static.

And just to make sure it wasn't just that pedal, I checked a buffered Fatpants (different buffer, same results). POP. Tried a mechanical bypass pedal. POP. Tried optical. POP. (But it was a little quieter.)

I'm seriously lost.

[jubal81]

Wish I had a good answer. I'm digging the opto-fet mute with the PedalSync chip. Completely spoiled by smoothness and silence.

[rullywowr]

Hey Jon, are you still playing that ungrounded amp?  This is a just a hypothesis but perhaps there is a ground potential difference which is causing some built up energy to be released in the form of a POP! 

[midwayfair]

Hey Jon, are you still playing that ungrounded amp?  This is a just a hypothesis but perhaps there is a ground potential difference which is causing some built up energy to be released in the form of a POP!

Good point, and the amp is the only variable I didn't change. I guess I'm going to have to suck it up and get my good amp down in the basement. I've really been afraid of carrying heavy things up and down stairs since I hurt my back last month, but I guess it's still under 30 lb.

Also, I hope this doesn't mean that the input cap on my HRD has gone bad.

[midwayfair]

huh, so ... I solved the issue with the buffered bypass one.

I took some measurements and saw that there was an absolute huge voltage on the source of the FET buffer, which was of course charging up and bleeding through the output cap. It was close to 2V by the time it got to the switch!

So I did some investigation and realized that I tied the gate to Vb for the op amp.

Ordinarily, I would have thought that would be fine (it's not like referencing Vb is unheard of in buffers), but apparently I was wrong. Oh well, it's fixed now.

Having such a huge voltage was probably charging up the input cap to the amp, so that explains why all the other pedals/bypasses were popping, and probably also explains why it still popped even when the power supply and FET were removed.

I'm not sure what the lesson I should take away here is, though ....