Scratchy Treble/Bass Pots Question

[bbaug14]

Could be insufficient filtering in the pre-amp supply node. (Are you using 8uf or 10uF filtering on the pre-amp node by any chance?)

If there is not enough filtering, then the V1 stages being supplied from the pre-amp node can start to self-oscillate (LFO) through the power rail. This causes DC to appear on tone stack pots etc that are supplied from that pre-amp node.

One cure is to increase the pre-amp R-C node's filter capacitance.

Another 'fix' is to AC-couple the stage that is driving the tone stack (to the tone stack) I've fixed this kind of self-oscillation this way before.

Not saying that this is your problem - trying to diagnose amp problems through a website (without having the thing on the bench in front of me) is part prior knowledge and part hunches.

Thanks for the tip, but I dont think this is it. I have 22uF at the preamp nodes (big black caps in the center of the board), which should be ample I think. Also, if this was the case, I would think the pots would be scratchy regardless of lead or bass setting. I've got two 22uF caps in the preamp with seperate grounding points. I'm using the "Larry" grounding scheme.

[bbaug14]

Here is the switch.

[IMG1152]http://i60.tinypic.com/2vcfc0p.jpg[/img]