# Popping Noise



## TheSin (Sep 22, 2020)

I’m trying to consolidate information from past threads regarding the topic of that annoying popping noise you sometimes get when engaging a pedal. Here are the main possible causes and fixes that I gathered so far:

-Faulty/dry solder joints at 3PDT
Fix: Reflow solder joints on 3PDT

-Lack of input and output caps & pulldown resistors
Fix: PEDAL PCB includes them on the majority of their PCB’s. Test these component values and capacitor leakages before installing them. Use high quality capacitors.

-Faulty input and output caps or pulldown resistors
Fix: Test these component values and capacitor leakages before installing them. Use high quality capacitors.
If you didn’t to test beforehand, check for DC voltage to ground at input and output wires. High DC readings indicate that there is an issue with either the caps, resistors, or faulty solder joints at these components. (My question: What are acceptable DC readings, if any?)

-LED causing the issue
Fix: Jumper LED switch at 3PDT to keep it on, engage the 3PDT, if noise is gone then it’s the LED. Proceed with one of the recommended repairs on the AMZFX page.
(My question: Would installing another or a smaller LED fix it?)

-Cheapie 3PDT switch
Fix: Replace it with a higher quality switch after you’ve tried everything above.

Please correct any mistakes/misinformation and add what you feel is pertinent. Thanks in advance!


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## Cybercow (Sep 22, 2020)

If the stompswitch is causing a 'popping' noise there are several potential causes. A smaller LED will NOT fix it.
Most, if not all of PedalPCB's PCB circuits exact a pull-down resistance to help prevent such noise.
Anther factor that can create switch-pop is having the indicator LED wired to the supply voltage AFTER the circuit filtering section. When the bypass LED is connected to power supply BEFORE the circuit's power supply filtering cap(s), it is far less likely to 'pop'.

Here are a couple of articles on switch-pop . . . .

What Really Causes Switch-Pop

Why Is My Guitar Pedal Popping?


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## TheSin (Sep 23, 2020)

Cybercow said:


> If the stompswitch is causing a 'popping' noise there are several potential causes. A smaller LED will NOT fix it.
> Most, if not all of PedalPCB's PCB circuits exact a pull-down resistance to help prevent such noise.
> Anther factor that can create switch-pop is having the indicator LED wired to the supply voltage AFTER the circuit filtering section. When the bypass LED is connected to power supply BEFORE the circuit's power supply filtering cap(s), it is far less likely to 'pop'.
> 
> ...



-I have a Paragon I just built and have switch pop on stage 2 and intermittent pop on stage 1. I am getting dc volt readings at outlet jack of pedal. I see that both circuits have an electro and film caps wired in parallel at outlet. Which one should I focus on testing, or both?
-On my seabed delay there is no pull down resistor to ground only a 1k in series with the electro cap. Big pop on this pedal, usually gets quieter after I engage it a few times. 
I eliminated the LED being the cause of issue on both pedals.


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## TheSin (Sep 23, 2020)

Btw what are acceptable ESR and Vloss readings on caps? Thanks!


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## Nostradoomus (Sep 23, 2020)

Most likely the electro cap is leaky...replace it with a film or tantalum cap and see if that makes a difference.


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## TheSin (Sep 23, 2020)

Nostradoomus said:


> Most likely the electro cap is leaky...replace it with a film or tantalum cap and see if that makes a difference.


Ok I’ll try that. Is that common to replace electros w film or tant? I always thought there was a reason that electros were there. Sorry, just trying to learn more here. Thanks!


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## Cybercow (Oct 4, 2020)

Personally, I follow a rule of thumb where any caps at or below 1µF are film or MLCC, spending on space allowed. Anything higher than 1µF, unless SPECIFICALLY called for, are electrolytic. It always depends on the circuit and WHERE in the circuit caps are applied.


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## HamishR (Oct 7, 2020)

I'll use a box cap for 1µF if there is room. Sometimes I'll use a tant or MLCC if room is extremely limited and honestly I can't say I've ever heard a difference. Electros do eventually wear out apparently although again - never heard it.  Except in very old amplifiers.

I've heard of power pop, K-pop, J-pop and synth pop. Now it seems we have switch pop.


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## TheSin (Oct 7, 2020)

HamishR said:


> I'll use a box cap for 1µF if there is room. Sometimes I'll use a tant or MLCC if room is extremely limited and honestly I can't say I've ever heard a difference. Electros do eventually wear out apparently although again - never heard it.  Except in very old amplifiers.
> 
> I've heard of power pop, K-pop, J-pop and synth pop. Now it seems we have switch pop.


....so many “pops” to choose from.
I’ve been experimenting on a couple pedals that I have this issue with...Swapping Input/output electro’s w film, changing 3PDTs, grounding pcb input, and even output, during bypass, reflowing solder joints, adding resistors in series at input and output (per Mr Black article), etc, etc...and while some of these have helped, there is still something else out there that causes this. Maybe the circuit, I don’t know???? 
One thing I do know is that this has improved my skills and knowledge, which is valuable!


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## TheSin (Oct 7, 2020)

TheSin said:


> ....so many “pops” to choose from.
> I’ve been experimenting on a couple pedals that I have this issue with...Swapping Input/output electro’s w film, changing 3PDTs, grounding pcb input, and even output, during bypass, reflowing solder joints, adding resistors in series at input and output (per Mr Black article), etc, etc...and while some of these have helped, there is still something else out there that causes this. Maybe the circuit, I don’t know????
> One thing I do know is that this has improved my skills and knowledge, which is valuable!


Definitely gonna invest in better caps & 3PDT’s, maybe even those soft touch ones, and hard wire them in so I can swap em more easily....no more breakout boards for me.


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## HamishR (Oct 7, 2020)

I think if you want better caps in a pedal then the ones to look at would be the electrolytics. I've never had any issues with red, grey or yellow box caps, or with MLCC caps.  And I've never seen the point in those switch boards - it doesn't take any longer to hard wire them IMO.

One thing I have noticed on seeing some folks pedal pics is the huge variation in soldering quality. If you have a clean, well prepared soldering iron at the right temperature and good resin core solder then soldering should be a quick and neat exercise. It should be easy to get a quick, shiny, quality joint. Speed is important because a lot of things melt rapidly if you hold the iron on too long. Switches are prone to melting rapidly if the lug gets too hot, the PVC insulation of wire melts very easily potentially causing shorts, and caps, transistors and ICs can be ruined by excess heat.

If you have sweaty hands then wipe down the PCB before you start soldering. If you are soldering on to a previously soldered pot make sure you can get the wire through before you start soldering. Doing things properly saves time in the long run.


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## TheSin (Oct 7, 2020)

HamishR said:


> I think if you want better caps in a pedal then the ones to look at would be the electrolytics. I've never had any issues with red, grey or yellow box caps, or with MLCC caps.  And I've never seen the point in those switch boards - it doesn't take any longer to hard wire them IMO.
> 
> One thing I have noticed on seeing some folks pedal pics is the huge variation in soldering quality. If you have a clean, well prepared soldering iron at the right temperature and good resin core solder then soldering should be a quick and neat exercise. It should be easy to get a quick, shiny, quality joint. Speed is important because a lot of things melt rapidly if you hold the iron on too long. Switches are prone to melting rapidly if the lug gets too hot, the PVC insulation of wire melts very easily potentially causing shorts, and caps, transistors and ICs can be ruined by excess heat.
> 
> If you have sweaty hands then wipe down the PCB before you start soldering. If you are soldering on to a previously soldered pot make sure you can get the wire through before you start soldering. Doing things properly saves time in the long run.


Concur 100%!


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