made a looper-switcher - how to get rid of "pop"

[boroman]

I recently build a 1-loop swticher pedal (so in, out, effects send, effects return), whcih uses 3PDT and a LED. Everything is fine but when I switch the loop on, I get a small click/pop so when delay effects is there it just going throught the delay so it's weird. I read I can get rid of it using 0.1uF cap (?) but where I should place it? Or are there any other solutions?

[mozz]

Disconnect the led and see if it still pops.

[boroman]

Disconnect the led and see if it still pops.

At first I said yes, second - no. I put the DC away from the switcher and it still "clicks"..

[mozz]

Switch to a different amp. Other than that, maybe 1 meg resistors on the input and output.

[boroman]

Switch to a different amp. Other than that, maybe 1 meg resistors on the input and output.

Do you mean, solder them in my switcher pedal?

[mauman]

Do you mean, solder them in my switcher pedal?

Yes, solder a 1Meg resistor between the tip & sleeve of each jack (one each on the in, out, loop send, and loop receive jacks.) Won't hurt and may help, if there's a capacitor in a pedal upstream, downstream, or in the loop that's causing the pop. Your switcher is not the cause of the pop, but adding these pulldown resistors can help prevent such ventriloquism.

[Mark Hammer]

You can look up the term "pedal ventriloquism" - a term I coined for the precise phenomenon described here.

Some background...

All electronically-switched pedals - Boss and DOD being the poster-children for this - require a buffer before and after whatever FETs are used to cancel or enable the effect. The output buffer will always have a terminating resistor that allows the DC-blocking cap on the output to always drain off. But the capacitor on the input buffer generally does not have a terminating resistor, and is simply "hanging" there.

Now, if your pedalboard is a bunch of e-switched pedals, then you might hear a "thunk", when plugging into the first one, but every single pedal after that has its input capacitor connected to the terminating resistor on the pedal just ahead of it. This enables the user to engage/bypass any of them as many times as you want, without any switching noise.

The problem comes when one mingles true-bypass pedals (which includes loop selectors) with e-switched. The TB pedal will mechanically lift and re-connect the path to the e-switched pedal after it. Depending on the value of the input cap on the e-switched pedal, that could result in an audible pop as a drain/bleed path is removed and then provided. You'll note as well that if one were to step on the TB switch several times (on-off-on-off), the popping goes away, as that input cap becomes more fully drained.

I called it "pedal ventriloquism" because the popping appears to come from the TB pedal, when really it is coming from the e-switched pedal it is connected to. That pedal seems to be "throwing its voice" and making the TB pedal; sound like its making the noise.

As others here have recommended, by simply providing a hard-wired drain path for the input cap on whatever pedal comes after the TB pedal, the problem will be cured. Ideally, something in the 1-2.2M range will suffice, without loading anything down. Solder it onto the lugs of that pedal's input jack. Should the time come to sell that pedal, you can easily unsolder it, for those who insist on something being absolutely "stock".