tripple fuzz de-scratch quest

[LP Hovercraft]

Love that versatile Tripple Fuzz!!!  I'm wondering if the Tripple Fuzz's gain knob just hates potentiometers or is ther perhaps another way to go about this.  Would the Tripple Fuzz circuit do the same weird scratchy cutty-outty thing when the gain knob is varied if instead one were to use a photocoupler connected in a configuration like this:   

The gain knob (controlling Q1's emitter to ground) is connected as a variable resistor to the anode of an LED connected to a 3.5ish volt rated LED (rated max voltage dependent-with a 4.7K resistor in series at the supply side for protection from a full 9V) with a 100K pot wired as a variable resistor to ground.  The photocell would be hooked between the emitter of Q1 and ground and would have a maximum dark resistance of 10K-25K. 

Just curious.

[soggybag]

If I understand what you are describing, I have experienced the same thing with my Tripple Fuzz. When the Gain knob is adjusted the sound jumps in volume. I wasn't sure if this was a problem with my build or not.

I'm not sure if a photocoupler would help the problem or not. My guess would be not. It seems if you could replace the pot with another type of variable resistor the same problem would still exist.

I was playing around with different clippin diodes and I could not really hear a difference. I ended up removing the clipping diodes altogether.

[LP Hovercraft]

So Q1's signal just gets jumpy as the resistance from the emitter to ground is varied no matter how it's done.  I was thinking of mounting this in an old Ernie Ball volume pedal, but am somewhat deterred due to the scratchiness.  If you turn it while you are not playing, It's not so bad.  Maybe I'll still build it this way.  Is there a lot less distortion without the diodes?

[slacker]

The pot is scratchy and jumpy when turned because it's got DC on it. So turning it not only changes the gain but changes the DC voltage as well. You could change it for a fuzz face type gain pot arrangement using a cap to ground, that would probably solve the problem.

[LP Hovercraft]

That's a really good idea!  Thanks!  The + cap side-to-wiper then pulls the audio nastiness to ground.   When I get back home, I'll give it a whirl.