SOLVED Tearjerker Wah Crackle/Scratchiness

[greggerypeccary]

Hi!

My Tearjerker build sounds great but there is some crackling when playing the guitar and sweeping the wah. It doesn't seem to happen when sweeping the wah with the guitar muted. I used a brand new "Black Top" 200k pot from Smallbear and I don't think it's the classic old pot noise. I think someone mentioned it could be a leaky cap? Does that sound feasable? I own a multimeter but would need a bit of instruction going about diagnosing this.

Thank you so much!

 

[Stickman393]

Not entirely sure what the mechanism of crackling is on these.

Leaky caps - this would be more common in electrolytics. I would specifically be looking at c3, the 4.7uF electrolytic cap. Early wah pedals used bipolar caps in this position.

IIRC, bipolar electrolytics are essentially built like two polar electrolytics back-to-back. They tend to have higher ESR and lower leakage than polarized electrolytics. I suppose it's possible that, if a leaky cap in this position causes crackling, that would explain this design choice in early wah pedals.

Another thing worth noting - most modern wahs use polar electrolytics in this position, but electrolytic caps have gotten considerably better over the decades. The eventual shift to polar caps could be due to the advances in low-leakage caps.

That's a bit of conjecture on my part, but TL;Dr, check out c3

 

[Nostradoomus]

Some pots are just dirty even fresh off the line, try some deoxit anyway and see what happens.

 

[greggerypeccary]

Thank you both! I'll report back with results.

 

[greggerypeccary]

Sprayed the pot with Nu-Trol... Crackle is gone! Silly me.

 

[Stickman393]

Schweet. Probably just a touch of dust in there then. Have fun brotha.