reference schematic - http://www.morleypedals.com/pwaes.pdf
The pedal was built on perfboard, tight layout. Sound very nice, much better sweep than that of crybaby, not so sharp or harsh. however, it hisses a lot. Bypass is dead quiet (all of the sound and none of the noise, gotta love the buffer), but i get nasty oscillations when the volume pot is turned all the way down (I used 100kA instead of P1, R8 and R7, maybe thats the reason). Bypass is as per drawing, the sweep is controlled directly by the potentiometer, w/o optoisolator, I used standard crybaby pot for that.
All in all - a much smoother wah pedal, more of an active treble cut filter. Interacts wonderfully with TS, RAT and such. The only problem is the hissing noise which pokes through once in the toe-down position. I took out the C4-R5 newtork and used 150pF cap instead. That has helped with the hiss, but also killed the treble a lot.
Possible mods - eliminate C1 or add a rteble cut cap (5-10pF) from pin 2 to gound.
Will report tomorrow on the progress.
I also made a preliminary layout. Once I figure out the vector graphics drawing, I'll post it here.
I used the PWA as the wah in my Vanishing Point,,,, sounds good...
I've also got a Power Wah and I don't have the problems you described... I would try replacing the volume section as per schematic...
The volume control has been wired as per schematic. Oscillations in bypass mode are gone.
Effect mode: the noise has diminished with use of 5532 opamp. However, the treble-most position is still waaay too noisy to use in front of a distortion.
Ideas, gentlemen?