[2299] Why Bypass Switches Pop

Date: September 12th, 2017 | Comments : [1] | Categories: DIY.

Why Bypass Switches Pop: updated to dispel the myth of static electricity.

Lab Notebook: Why Bypass Switches Pop


One Response to “Why Bypass Switches Pop”

[779554] Mark Hammer Says: 9:31 am, September 22nd, 2017

There is something I like to refer to as “pedal ventriloquism”. This is what occurs when a person has one or more electronically switched pedal that have been performing well, and then inserts a true bypass pedal into the mix.

E-switched pedals, like those by Boss, generally have an unterminated input cap, like what Jack shows in the first illustration. Users will experience a brief “thunk” when first plugging in, but since switching is done within the circuit in that pedal, rather than *around* it, no further thunks will be experienced when switching after that first one.

HOWEVER, if a true bypass pedal is inserted just ahead of one such e-switched pedal, every time you hit the stomp switch, the input cap of the e-switched pedal is momentarily disconnected and reconnected, and the user will experience some switch-popping, for the reasons Jack describes.

I refer to this as “pedal ventriloquism” because it is not the TB pedal that is popping; the user merely *thinks* it is, because the pre-existing pedals never popped in the user’s experience. The new TB pedal is “throwing its voice” to the e-switched pedal, and making it pop.

As would be true of any non-e-switched pedal with an unterminated input cap, a couple of quick on-off switches, and the pedal seems to be cured of popping, because the current in the cap gets drained off and hasn’t had time to accumulate…yet. An easy cure for such ventriloquism is to simply stick a terminating resistor in the e-switched pedal, between input and ground, such that any excess/stored current is always draining off. In other words, the cure for an unterminated e-switched pedal is identical to that of an unterminated TB pedal.


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