tonepad's fukurban octup

[robotubo]

i recently built the fukurban octup at tonepad.com

I replaced q3 and q4 with 2n5458s instead because the local elect store didnt have 2n5457s

i dont know whats wrong with it, it just distorts my signal. is it because I did the swap? Please help.

The signal is fine even with the pedal on so I know the circuit works.  The volume trim pot works perfectly, the bias trim pot just gives me a sort of distortion. 

Can anyone tell me what's wrong with this? Thanks guys.

[Colonel Angus]

After reading the build reports on Tonepad, it sounds like your circuit may be functioning properly. The descriptions make it sound like "clean octave" is a bit of a misnomer. Everyone reported a fuzzy tone with a ring-mod esque octave. I haven't built this one but that is what I gathered. Hopefully that sheds some light.

[robotubo]

Thanks so much. I will check that out

[Earthscum]

If you are looking for a perfectly clean octave up out of this, you can remove the 10 from the Source of the jfet pair. In my experience, this gives you somewhere around unity, but it's nearly perfect, so the effect may not be apparent until you overdrive it in a later stage. The cap would be the 10uF at the lower right corner.

In case you're interested: If you run an LFO to the bias pot you get a phase warbling kind of sound (the phase of the output rocks back and forth). I showed my experiments HERE.

ETA: If you have a 10k pot handy, you might try wiring the positive leg of the 10u to the center lug, and tie lug 3 in where the leg of the cap went. This should give you a variable gain to get the signal cleaned up a bit without losing all the signal strength. Another option would to be replace the 10k at the Sources of the jfet pair with a pot, lug 1 to ground, lug 3 to the source, and the wiper goes to the positive leg of the cap.