Earthbound audio Supercollider issues

[JebemMajke]

I ve made this version of big muff using this schematic
And i get sort of upper octave sound even on sustain to the max. I 've used trimpots in places of collector resistors. So voltages are biased to 4.5 v ( except q2 which can not go lower than 7 v ( 22k trimpot )). I ve took the output from q3 collector and i gotta tell you its a beast, no upper octave, a killer muff. So i guess tone stack must have issues. Any advice?
Tranistors are q1 mpsa18, q2 and q3 bc549c's and q4 bc 550c.

[runmikeyrun]

try these things:

Adjust your trimpots so they read 12k each.  Replace the one that only goes to 22k with a different trimpot or a 12k resistor.  See how it sounds.  It might be just fine after that.

Failing that-

 You have to find out if it's your tone stack or 4th gain stage that's producing the octave.  Eliminate your tone stack and jump the collector of Q3 to the base of Q4.  Don't forget to put in a cap, a 100n should work.  Octave?  Then check the gain recovery stage.  If not, run Q3 into the tone stack and usual but connect the 100n off lug 2 of the tone control directly to your volume pot.  Octave?  Then the problem is in your tone stack.  

You can also use an audio probe, I believe there's a sticky on it.  You can take output from any part of the circuit and then when you hear the octave that's where you need to start looking.

Unfortunately I sold my supercollider so I can't measure voltages for you.  Sorry.

Just for fun, here's a link to a video of the supercollider I built from this schematic... guitar and bass both: