DC current on tone pots.... effect?

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3,766
Just curious. I don't know if any tone was improved, but I noticed my mid pot on my marshall scratchy when I'd turn it when playing.

SO I replaced the .022uf Sozo Mid tone cap and the scratch is gone.

Just wondering what DC current over a leaky cap into tone pots might do to the guitar signal/tone..etc?
 

Billm

Member
Messages
574
DC on pots = scratch.

But you already figured that out!

It's likely that there would be no other effect on tone.
 

pdf64

Member
Messages
6,849
As long as it doesn't get to the following grid, which in this case it wouldn't as there's another coupling cap in series.
If it did, the bias / operating point may get shifted.
Pete.
 

Ronsonic

Member
Messages
3,306
Just curious. I don't know if any tone was improved, but I noticed my mid pot on my marshall scratchy when I'd turn it when playing.

SO I replaced the .022uf Sozo Mid tone cap and the scratch is gone.

Just wondering what DC current over a leaky cap into tone pots might do to the guitar signal/tone..etc?
Couple of things. It makes the pots with the DC on 'em noisy. If enough gets through to the grid of the next tube stage it messes up the bias and then you get all kinds of bad stuff like muddy sound, fuzzy blobby distortion or even melt down the tube. Believe it or not a 12AX7 can redplate.
 




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