Popping sound when pedal is engaged

[Baran Ismen]

Here i am with a new problem..

I Got this m wave mini universe reverb pedal some time ago. It sounds absolutely killer, but theres a problem with that ls been there since the beginning and lots of people also experience.

When engaged, it pops! It pops and introduces this into the reverb sound. Weird thing is, the longer the pedal stays active, the lesser this popping effect becomes when switched on and off. It makes me think of a capacitor issue, but seems like lots of people complain about it on YouTube comments. There is also a slight delay of the sound like 10 15ms.

I tried several resistors between gnd and in/out tips separately, but no luck. I also measure around 400mv when the pedal is engaged freshly between in(or out) and gnd leads, and it decreases to nearly zero within a minute or two, and as it lessens, popping sound also diminishes.

Any brilliant ideas?

[antonis]

Disconnect indicator LED and try again..

If popping issue persists, ground IN & OUT (via aligator clip or so..) when effect is bypassed and disconnect clips AFTER effect is engaged..

Come back ONLY if popping persists despite utilizing the above..

[bean]

You've got some leaky coupling caps at input and/or output. Or, possibly a lack of effective circuit grounding. Or, the design is such that there are no coupling caps at all (like say a split rail where they decided to cheap out on a couple parts). Or, they've used a cheap 3PDT with significant mechanical popping. Not all 3PDT are created equal.

Reverb is one of the worst offenders because any mechanical noise, however small, will sound infinitely worse because of the nature of the effect.

[Baran Ismen]

If popping issue persists, ground IN & OUT (via aligator clip or so..) when effect is bypassed and disconnect clips AFTER effect is engaged..

That way I'll have no sound?

[Baran Ismen]

Further notes that;

1- Two red-circled pins BOTH have 3.3V, that are connected to the LED's resistor on the front side (R1). I've never seen an application before where 2 pins of the 3pdt are occupied with live voltage.

2- Shorting GND and Middle pin of the switch leaves the LED open (as expected) no matter if the pedal is closed or open, BUT the short delay when the pedal is engaged is gone.

I think that when I close the pedal, the effect is also grounded, or reset somehow because when I activate the pedal, say in shimmer mode, the effect starts to rise from scratch. But when done as above, switching does not affect the decay, it just goes on in the background, which sounds more natural. It'll be easier to explain with a short video tonight actually  Unfortunately, popping is still there on this scenario.

[Lino22]

Did you try to disconnect the LED as Antonis suggested? In my experience it is almost always the LED, then it can be leaky caps but that one is easy to sort out and companies know how to. Disconnect the LED and try it out.

[Baran Ismen]

After detailed research on YouTube and obligatory learning of basic Portuguese , I've found that someone fixed this (big caps to Google Translate)

https://www.youtube.com/watch?v=c79RCgKpOlQ

It's an input & output resistor trick indeed, but I've tried no less values than 470k, he uses 220k for both and claims that it does not affect the tonality. I'll give this one a try tonight.

[Baran Ismen]

Did you try to disconnect the LED as Antonis suggested? In my experience it is almost always the LED, then it can be leaky caps but that one is easy to sort out and companies know how to. Disconnect the LED and try it out.

I'll also try this, because there's definitely something to do with the LED as when its permanently on (shorted with 3v3), there's no delay happening when the effect is engaged and the decay goes on when dis&reengaged. Semi-trail effect, we can say.

I'll try another workaround like feeding the LED directly from power input with a 4.7k LED and connect to the switch, not via the board. Good old DIY'er style!

[Lino22]

There is a way to wire 3PDT true bypass so the input and output are wired to GND in bypass. No pulldowns necessary.

[Baran Ismen]

There is a way to wire 3PDT true bypass so the input and output are wired to GND in bypass. No pulldowns necessary.

I know, I've even thought about changing the switch completely, but this one is just a bit smaller than the regular ones and their legs do not fit into the board. Say I disregarded that and used cables to connect everything, then the small size of the enclosure kicks in, and regular 3PDTs won't fit in height. I doubt that can be done over the current PCB.

[antonis]

If popping issue persists, ground IN & OUT (via aligator clip or so..) when effect is bypassed and disconnect clips AFTER effect is engaged..

That way I'll have no sound?

Of course but you'll verify the existence (or not) of leaky caps..
(you'll leave no time for caps leakage..)

P.S.
As far as input impedance domination isn't an issue, proceed with in-out low value pull-down resistors..
Just take into account RC time constant in conjunction with  effect ON/OFF time period..

[Baran Ismen]

If popping issue persists, ground IN & OUT (via aligator clip or so..) when effect is bypassed and disconnect clips AFTER effect is engaged..

That way I'll have no sound?

Of course but you'll verify the existence (or not) of leaky caps..
(you'll leave no time for caps leakage..)

P.S.
As far as input impedance domination isn't an issue, proceed with in-out low value pull-down resistors..
Just take into account RC time constant in conjunction with  effect ON/OFF time period..

Low value is the key here I guess, komşu. Guy in the video uses 2x 220k's, whereas I've tried 510k, 1m, 4.7m and 10m resistors.    

[antonis]

Low value is the key here I guess, komşu.

Quite right, arkadaşim..

But you have to understand the RC time constant of resistor/cap filter (I let you deside if it's a HPF or LPF.. ) to estimate the time needed for capacitor fully discharge (4 to 5 times RC..)
(in the mean of there isn't a resistor "stadard" value for all cases pop elimination - except for"short", of course..)

[Baran Ismen]

Low value is the key here I guess, komşu.

Quite right, arkadaşim..

But you have to understand the RC time constant of resistor/cap filter (I let you deside if it's a HPF or LPF.. ) to estimate the time needed for capacitor fully discharge (4 to 5 times RC..)
(in the mean of there isn't a resistor "stadard" value for all cases pop elimination - except for"short", of course..)

220k on both didnt do the trick. Also removed the Led and no go.

Your trick also didnt seems to help (shorting pcb in and out to gnd)

[antonis]

220k on both didnt do the trick. Also removed the Led and no go.
Your trick also didnt seems to help (shorting pcb in and out to gnd)

Then put the blame on the 3PDT switch..

[Baran Ismen]

Ok, i tried 2.2k on both and it worked finally, popping is %98 yone. I also think that i have found the reason for both popping and delay.

I think its because the pcb input is connected to ground when pedal is disengaged, and when you switch on, theres an abrupt delay and the effect starts to do its job. Say you set a Long decay, dis and reengage resets this. But i also found a way to overcome this, yet the Led stays on all the time.

I explained everything in the video below.

https://youtu.be/pzV6-AYBkaQ?si=gSkpybrNTavZAElw

[antonis]

Ok, i tried 2.2k on both and it worked finally

You do realize that 2k2 is a ridiculous input impedance, don't you..??

[Lino22]

Fuzz Face has input Z about 10k and that is really low and causes troubles to pedals placed before it.

[Baran Ismen]

Ok, i tried 2.2k on both and it worked finally

You do realize that 2k2 is a ridiculous input impedance, don't you..??

I know, i havent tried this on my pedal board yet, Just connected to my pc individually, but ill give it a go tomorrow, but also tried 27k and it also worked good. Interesting that higher values such as 510k or 1m did not work.

However, i still believe that the main problem lies beneath the design itself. Its a true bypass indeed, but the effect does not run in the background. Take a phaser pedal for example, as Long as its powered, phaser effect runs in the background and when you switch on and off, it does not reset its cycle. I believe its the case here.

[Baran Ismen]

One thing that I could not still understand (the logic) is the term of impedance.

Can someone explain to me what impedance is and how does it affect like explaining to a monkey? I mean, literally the most basic way possible with real-life examples even 

Seems my pick-ups have an output impedance of 1K. How good is it? That means the output current has just a little "resistance" to go out from the guitar?