afterlife popping

[jimilee]

I usually use a 1m across the lugs on the input, seems to work.


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[Boba7]

Yeah I tried everything.

I have a 2M2 from input to ground, tried different values there (100k seemed to lessen the "pop")
I tried different values on the output to ground too (knowing it shouldn't make a difference as the output is a pot, but I also remembered a Big Muff that popped until I put a 220k from output to ground)

And I also tried 100r and 1k resistor inline with the input and the output (see Mr Black page on popping 3pdt)

Nothing has worked so far.

There's no DC voltage that I can measure on input or output, with the switch both engaged and disengaged.

My guess is the 3pdt is a noisy one and the compressor amplifies the noise.

I'm gonna try another 3pdt and maybe a relay bypass. If it still pops, then I'll just give up...

[electrosonic]

Maybe the led on/off pulse is coupling with the audio? Disconnect your led and see if it goes away.

Andrew

[madbean]

I think the best you can do here is 1M each on R1 and R2, and increase C1 to 22n or 47n. You lose the extremely high input impedance but it's still going to be plenty high enough by guitar standards. If it still pops then that's pretty much the end of the road unless you maybe try a relay type bypass.

Noticing that my 4:1 has a decent amount of pop on it, too. That's basically the same circuit with a clean blend.

[Boba7]

Andrew: Yeah I thought about it too and disconnected it with no luck...

Brian, I have right now a 2.2M for R1 (tried also 1M), 1M for R2 and 10nf for C1. I tried a 100nf in parallel with it with no better results.

Wondering what causes the pop and if a relay bypss would actully get rid of it or no... Ah ah that'd be frustrating! Already working on a 1590a boxed effect is a bit stressful I must admit.
Well now Im even wondering if I should change the switch at all...

[madbean]

It's possible the popping is coming from the circuit output, actually. A bit unusual but it can happen (generally mechanical popping is noticed at the input because it gets amplified throughout the audio circuit). Try tack soldering a 1M between the circuit output and ground on your 3PDT and see if that does anything. I'm just guessing at this point.

[Boba7]

Oh yeah I did that too... 2M2, 1M, 220k and 100k... No difference...

Now Im thinking of doing those mods: http://stompville.co.uk/wp-content/uploads/2012/02/105SV.png

LP filter at the input to filter RF frequencies, a 1k between the 10nf and opamp, and 100r between the 1uf and volume pot at the output.

Thanks for taking the time to help!

[electrosonic]

Does changing the sustain knob change the amount of pop? The circuit actually has a lot of gain when there is no signal. I would guess the pop is being amplified - if that is the case, maybe a relay w/mute would be a solution.

Andrew.

[Boba7]

Andrew, no it doesn't seem to change the amount of pop. Only the volume affects (logically) the amount of pop.

But even with the circuit unpowered, there's a pretty loud pop. The 3pdt must be on the noisy side.

Do you guys think a 1k between the input cap and the opamp and a 100r between the output cap and volume pop could do something?

[Boba7]

Ok so I tried everything, even changed the 3pdt, the pop is still there.

But I'll live with it since its the best compressor I've ever played!!

[jimilee]

Is it going to be an always on pedal anyway? The one I built, I didn't even use a stomp switch.

[Boba7]

Nope not always on, although it really could, it's the most transparent compressor I've heard!!

But no, I already drilled the enclosure, and I want to be able to switch it on/off.

So after trying literally everything, the only thing that reduces the pop is a 100k as a pulldown resistor at the input of the circuit. Very odd. I know it lowers the impedance a lot but I can't hear any loss of highs. Is there any problem I might run into with such a low impedance??

What a BEAUTIFUL compressor. I'll post pics soon.

[Boba7]

So I guess it was time for relay true bypass in a 1590a enclosure...

My wiring with the 3pdt was so clean, I was very proud of it. Now it's a bit messy as I just reused the same wires to go to the relay bypass board. Oh well...

Build report soon to come.

With the sensitivity mod, it's just THE perfect compressor.