SHO tone talk !!

[MikeH]

As I stated above, you might look into a BMP style tone control.  It can act as both a high pass or a low pass filter and would be a flexible solution.  Swapping caps will definitely work, but will be impossible to adjust on the fly.

http://www.muzique.com/lab/tone3.htm
http://www.muzique.com/lab/tbypass.htm

Another solution to consider would be to use a 2 or 3 position toggle, or even a rotary switch, with some different values for input caps.  That would allow some flexibility.

[Gus]

If you look at the schematic it looks to have about a gain of about X1 at min setting

What happens as the gain is increased due to the drain to gate resistor feedback path?  Think about it

I would guess as others posted the issue might be you speaker(s) or amp being over driven or maybe you are clipping the output of the SHO.  What is the input of the SHO connected to a guitar a bass another effect?

"Cut the gain and increase the clean volume" ?     increasing the gain increases the volume

If you want an input high pass think about it what is the input resistance of the SHO when the gain control is set to 1 o clock? What is the gain? are you clipping the output?  Calculate the input cap knowing the source feeding the SHO and the desired RC time constant that set the high pass filter.  .047uf might still be to high depending on the speaker(s) and amp after the SHO.  Also don't forget about the Miller cap of a small MOSFET if you study the circuit.

[pinkjimiphoton]

i added a master volume to mine...just a 1meg pot (50k worked better, actually) wired up as a variable resistor between the 0.1 cap and the 1m resistor if memory serves...
it's on the band truck at the moment, so i can't look at it, but it definitely helped tame the boost some.

it may have replaced the 47k resistor too...shoot, i am too brain dead to remember!! on mine, as soon as you kick it on, there's an easy 6db boost, maybe more. if it's too muddy, try a .047 input cap as others suggested, or even a smaller one. on mine, it's kinda trebly even with the .1mf cap.