the "pop" (reduction) that failed...

artsinbloodshed · July 11, 2011, 06:20:22 PM

Quote from: Paul Marossy on July 11, 2011, 02:37:59 PM
Quote from: Gurner on July 11, 2011, 02:12:49 PM
Without wanting to reaffirm the obvious, you've got to narrow down the source of the popping....because without knowing what's causing it, you can't eliminate it conscisely

My efforts would be going into *proving* it was the LM386....vs just swapping it out for another variant & hoping that fixes the problem.

Do you get popping with the RH side of the 0.1uf output cap shorted to ground (I'd be surprised if you do!)
Do you get popping with the LM386 input cap pulled or pin 3 grounded ? (this is perhaps the most revealing test as it helps establish whether the "pop" is being sourced prior to the LM386 input or getting into the LM386 "up the tradesman's entrance"....ie the supply rails)

Edit: Just to confirm - you said you're supplying the power from a wall wart....you're not switching this on/off here at the same time are you?

Yeah, I agree. I made my statement based on the assumption that all other possibilities have been elmiminated. Good point about the switching power on/off with the switch. That would definitely cause problems...

No,the pedal is fed by a wall wart but i'm just switching the effect on and off (the regular way).
My guess is that it comes from the LM386 itself because I tried to disable the buffer at the input and the pop was somehow "reduced"...but with all the advices you gave I think i'll have some work to do !:)
I have a question though: What is the "RH" side of the cap?

Gurner · July 11, 2011, 06:54:19 PM

Sorry RH = right hand side ....meaning as I look at the schematic, the output side of your output cap. There ought to be zero pop when you short that to ground, but like I say don't run your guitar signal through while this condition is in place, as by doing so you're presenting a direct short to ground for an LM386 output AC signal. Just short to ground & try switching on/off to see if a pop is audible.

Paul Marossy · July 12, 2011, 11:08:14 AM

Just out of curiousity, what FET did you use in your build?

artsinbloodshed · July 12, 2011, 02:25:38 PM

I use some stock MPF 102...
As I said, with the buffer shunted the popping remains audible...

Paul Marossy · July 12, 2011, 03:19:19 PM

What happens if you use a battery instead of the wall wart? Also, what voltage are you getting out of your wall wart? If it's higher than 9V, then that might also be a contributing factor as it's operating on a higher voltage than it was designed for.

I have one build that pops when on a regulated 9V wall wart common power supply on my pedal board, but doesn't if that pedal specifically is on a battery. It's weird and I have never figured out why it does that.

artsinbloodshed · July 14, 2011, 07:57:02 AM

no batteries, just wall wart...and the wall wart gives a good 9,67 V after measuring...
I have no 9V battery available for now and I cant' buy one today (bastille day)...first thing i'll check tomorrow...
It's a uber simple build but there's so many ways to get that popping that it stuns me!

Paul Marossy · July 14, 2011, 09:48:22 AM

Just trying to eliminate the power source as being the problem.

I don't remember if I already mentioned this, but I made a clone of a pedal that I won't name here, and I can't use it because it has a problem with making popping noises when switching. Does it only when on a wall wart common power supply with the other pedals on my pedalboard, but not when that one specific pedal is powered with a battery. I am still baffled on that one. Anyway, it's a drag because I just don't do batteries. 98% of my builds don't even have room for a battery in them, they are powered by wall wart only.

artsinbloodshed · July 14, 2011, 04:58:06 PM

Quote from: Paul Marossy on July 14, 2011, 09:48:22 AM
Just trying to eliminate the power source as being the problem.

I don't remember if I already mentioned this, but I made a clone of a pedal that I won't name here, and I can't use it because it has a problem with making popping noises when switching. Does it only when on a wall wart common power supply with the other pedals on my pedalboard, but not when that one specific pedal is powered with a battery. I am still baffled on that one. Anyway, it's a drag because I just don't do batteries. 98% of my builds don't even have room for a battery in them, they are powered by wall wart only.

Yes, I don't do batteries either. My statement is that batteries suck hard.it's not reliable (in a stagewise manner) and it's not eco friendly...
just to mention: The popping problem remains when on battery.
the battery gives a 8,54 voltage after measuring...

Paul Marossy · July 14, 2011, 06:24:04 PM

Gee, this is a weird one. Not sure what else to suggest!

artsinbloodshed · July 14, 2011, 07:24:01 PM

i warned you it was a weird one!

I tried to swap all the LM386 I had,disconnected all the buffers,re-connected the buffers,put a resistor in serie at the input (10k), add a RF filter at the input and swapped the pulldown resistor from a 15k to a 22M value...
and...the song remains the same...
WEIRD!

Darn it's a bummer, the stomp totally kicks ass, except that killing popping noise...
I'll try a third build to see...

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the "pop" (reduction) that failed...