Build Your Own Clone Message Board

As Cliff Clavin would say..."Switch pop, what's the deal with that?"

I've been seriously into building pedals for a year now and have completed many kits from many different vendors (BYOC is the best one hand down!).

With some builds, irregardless of vendor, the foot switch makes a "pop" when engaging or disengaging. I've tried to swap out foot switches, but that doesn't seem to decrease the POP. I don't know enough about circuits yet to make any attempt at analyzing this.

This isn't a tech support kind of question, just request the very experienced builders help me understand what the cause can be and how to avoid it. Can the switches be tested for this? Wonky solder joints? RF interference? Nature of some circuits?

Thanks for any help, it's sad to have a great sounding pedal that can't be used live due to this issue.

This is a notorious problem in our racket. True bypass switching sometimes just pops. It's worse with some circuits than others, but even building to the exact same spec, one build might pop and another might not. The problem is that sometimes it's an error with the build, but sometimes it's just… bad luck.

Some PCB shops sell relay bypass conversions that replace the switching mechanism with one that is guaranteed to be silent. I am going to try that on one of my builds that is popping and see if it helps.

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Scott

My band, Austin Hollow

True bypass switch pop is almost always caused by a small amount of DC voltage buildup on the pedal input or output. This could be caused by voltage leaking out of the input or output of the pedal. When you switch from bypass to effect mode, the pop is caused by the audio signal "meeting" the voltage present on the circuit input or output.

This is usually either caused by DC leaking out of the circuit input or output (from bad circuit design or from a leaky input or output cap) or it can even be caused by static electricity. True bypass circuit designs usually include pull down resistors on the circuit input and output to combat this (typically 1-2 meg in the input and 100k on the output). The function of these resistors is to allow any DC voltage present to drain away to ground without dumping too much audio signal to ground. This system fails when the source of the voltage is too great for the pull down resistor to effectively dump it to ground.

Here is the best article I've read on the subject: https://www.mrblackpedals.com/blogs/straight-jive/6629778-what-really-causes-switch-pop

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MasterDelayer/Reverbrador/Ampaholic/TopJacker

That is a great article. Lots to wrap my head around!

Thanks for the insight, 'tis a frustration for all it seems. Maybe I'll get around to building a Super 8, then all the pretty lights can stay on and switch pop won't be so much of a concern.

Anyway, thanks!