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

[artsinbloodshed]

Hey guys...
I know "popping" is quite common and I read almost everything about it and actually,this is the first time I failed to get rid of it...
I built the "grace" schematics...it really kicks ass but the popping when stomped on is so audible that it kills any pleasure.
heres's the link for the schemo:
http://runoffgroove.com/grace.html

-the dc is filtered by a 100uf cap (added)
-added a 10k resistor at the input for dissipation.(popping with or without)
-No leaky cap (coupling or decoupling)
-3PDT (input grounded) AND millenium are equally popping.
-The led's not the problem (popping with or without)
-No voltage at the input or output when bypassed
-I even managed to add a 1M pulldown resistor at the input and output (just to be sure...) ...not effective...

Now i'm running out of ammo...so what's your guess guys?

[skumberg]

Try using one of the outer lugs on the 3pdt for connection to the output jack. See illustration.
- - - <----
- - -
- - - <----
I had this problem with a switch. The centerlugs created a thumping noise during switching. Inside a switch there is a piece of metal that rests on the middle lug and flips between the outer lugs. If the connection between the center lug and the metal piece isn't smooth enough during switching a noise might develope. If the centre lug is connected to the output at all times this will be heard.

[artsinbloodshed]

I used this configuration:
http://gaussmarkov.net/wordpress/thoughts/wiring-up-a-1590b/
The pop is as audible as with the center lugs...
I tried a millenium bypass and the problem remains the same...plus I prefer 3PDT's
The 3pdt does not seem faulty...
Where the heck does the pop come from?!!!

[R.G.]

I believe that one very likely route is that it's coming in capacitively through the input wire, enabled by the very high impedance of that JFET gate and the 4.7M input resistor.

To test that, temporarily solder a 100K resistor across the 4.7M input resistor. If the pop decreases or is dramatically smaller, it gives you a place to work.

[artsinbloodshed]

by "across" you mean lug to lug, right?

[artsinbloodshed]

So, I soldered a 100k resistor across the 4,7M... there were absolutely no change...loud popping.
I socketed the 4,7M res and tried different values from 100k/1M/10M...still no change.
I even changed the LM i.C AND the switch...no change at all....
I'm totally clueless...
Any ideas guys?

[R.G.]

So, I soldered a 100k resistor across the 4,7M... there were absolutely no change...loud popping.
I socketed the 4,7M res and tried different values from 100k/1M/10M...still no change.
I even changed the LM i.C AND the switch...no change at all....

OK.
1. Using your DMM to measure resistance, measure the resistance from the input jack ground bushing to **every single point on the schematic** that shows a ground symbol. Do this with the power off. All of them, without exception must show less than one ohm resistance.
2. Set your DMM to measure DC volts. Power the effect and insert a jack if it needs this to turn the power on to the insides. Now measure the tip/signal contact on the input and output jacks in both bypass settings and record the voltage. This must be within 10mV of zero volts or you will hear a pop caused by the DC voltage when you change the bypass switch.

[artsinbloodshed]

i'm not really sure to understand what you're saying in 1 and 2 (being not a native english, some technical terms are tricky).
1: measure the resistance from input jack ground and "touching" every spot marked "ground" on the schemo?
2:measure dc voltage from input tip (to ground) and output tip (to ground)?

anyway, having built 2 pedals with both 3PDT and millenium bypass, here's what i've found (kind of amusing...) on the millenium one:
loud popping as well + the LED starts to glow as soon as the volume is set at (about) noon and more or the distortion level set almost at full throttle...

[R.G.]

i'm not really sure to understand what you're saying in 1 and 2 (being not a native english, some technical terms are tricky).
1: measure the resistance from input jack ground and "touching" every spot marked "ground" on the schemo?

No problem. Sometimes I think I'm not a native speaker of any language. 

Set your meter to measure resistance. Arrange the circuit board and wiring so you can touch any point you need to with your meter probes. Make sure the pedal is not powered on for this test. Clip the black/negative meter lead to the grounded connection on the input jack. Now use the red/positive probe to measure the resistance from that input jack ground terminal to each and every place in the circuit that the schematic shows should be connected to ground.

This is because what you describe could be caused by a bad connection to ground somewhere. So you are testing to see if all places in the circuit that should be connected to ground actually are connected to ground. If not, that could be causing part of your problem.

2:measure dc voltage from input tip (to ground) and output tip (to ground)?

Set your meter to measure DC voltage on a scale of 0-2V. Arrange the circuit board and wiring so you can touch any point you need to with your meter probes. Make sure the pedal *is* powered on for this test. Clip the black/negative meter lead to the grounded connection on the input jack. Now use the red/positive probe to measure the DC voltage on the signal (or "tip") contact of both the input jack and output jack, in both normal and bypassed  settings.

If there is DC leaking from the effect, this should detect it. If it is, and it's over 10millivolts, it would cause audible popping.

anyway, having built 2 pedals with both 3PDT and millenium bypass, here's what i've found (kind of amusing...) on the millenium one:
loud popping as well + the LED starts to glow as soon as the volume is set at (about) noon and more or the distortion level set almost at full throttle...

This indicates that the Millenium is incorrectly wired. Properly wired and with parts in the right places, this does not happen. It may be a more general wiring issue with the bypass switch and jacks as well.

[artsinbloodshed]

Ok,well...R.G...
I did everything you told me to do and here are the results:
checked the Resistance value and R<1.
checked the DC voltage and I can't read nothing weird. DC=0 (when On or Off)
I couldn't tell if it was within the 10mV...my brand new dmm died on me and i had to rely on an old analog one...
The pop was still audible.
I wired the 3PDT as J.D Sleep described on digital guiatr gadget...still popping.
Just to try it out, I soldered the input wire just after the buffer (before the input capacitor) and I noticed a less audible pop...could it be a clue toward the solution?

[artsinbloodshed]

more infos...
I bought a brand new DMM and tadaah,i could finally check everything correctly!
So, as I said, the R value is always < to 1 ( every grounded point) and the V value is always 0V when on and off (powered).
just in case, I checked the voltage of my dc brick and it brings 9,67V to the pedal...maybe it could have an impact.
I changed th LM 386 but same popping.
Anyway,I'm now officially clueless...
Electricity fairy,god of electronics, I'm summoning your help...

[Paul Marossy]

I built a clone of something, which shall remain nameless, and I could never figure out why it popped.

It would not pop when powered by a battery, but it would pop when on a common power supply with other pedals. Weird, huh?

[artsinbloodshed]

yeah,weird...sometimes you just can't know what is happening despite all your knowledge...
Sometimes it's just some beginners mistakes,sometimes it's just the sum of tons of events...I say Butterfly effect!
Anyway, does anybody knows if LM 386's are known to have Popping probs?

[Paul Marossy]

yeah,weird...sometimes you just can't know what is happening despite all your knowledge...
Sometimes it's just some beginners mistakes,sometimes it's just the sum of tons of events...I say Butterfly effect!
Anyway, does anybody knows if LM 386's are known to have Popping probs?

There is one remote possibility I suppose regarding your popping problem.

There are a few different versions of the LM386. The LM386-N1 thru LM386-N3 have a maximum voltage rating of 12V, and a min of 4V. The LM386-N4 has a max of 18V and a minimum of 5V. It might possibly have something to do with the difference between the two, maybe in how much current it draws when you switch the circuit on. Might be enough to make a difference?

I can't remember, it's been several years since I've done anything with an LM386, but I remember that some circuits care whether it's an N4 version or not. That's the only thing I can think of. Might be grasping at straws, though.  

[artsinbloodshed]

Ok then, I'll try different Lm386 N-something...
I think that the one inside the stomp is a N-1...I should have a N-3 sleeping somewhere.
Maybe it's time to swap and see if any good results could come out of it...

[wavley]

The Dirty Boy pedal guy say that you should just deal with it because it saves batteries and you should just engage pedals on the downbeat and it won't be a problem!

[Paul Marossy]

Ok then, I'll try different Lm386 N-something...
I think that the one inside the stomp is a N-1...I should have a N-3 sleeping somewhere.
Maybe it's time to swap and see if any good results could come out of it...

My hunch was based on a *possible* difference between the N-4 and the other three versions. I doubt that you notice any change between an N-1 and an N-3, but you never know...

[Seven64]

try adding a 0ohm resistor as the jumper for when the pedal is bypassed. 

you may also try a 3pdt switch pcb like the one from smallbear if all else fails.

[Gurner]

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! Be quick with this test & don't put an ac signal into your LM386 under this condition...as clearly you've a direct AC "short" to ground....not good for the LM386 at all)
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 via the supply rails)


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

[Paul Marossy]

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...