TimTom,
Thanks for bringing that manual discrepancy to our attention, but upon reviewing the manuals i’m not sure what written instructions and image are referring to in the manuals. We definitely want to make the manuals as clear a possible so I’m really interested in making these changes…so let me know what image and pages you are referring to.
It sounds like you will have to play around with the HPF and LPF trim pots to get the tone you are after. Just to make sure both optocouplers are working correctly, start up the pedal in “calibration mode” with the depth knob off (fully counter clockwise) and adjust the harmonic mix knob so that you can tell if both optos have signal going through them. It sounds like they are probably both working because of the issue of it sounding very bright when driven by another pedal…but just double check, if you haven’t already. But the brightness thing is an interesting issue. I think this is happening because the high frequencies have much less impedance getting into the pedal than the low frequencies (because of C1). You should be able to adjust down the HPF trim pot to make up for this. Another fix would be to put a capacitor in parallel with R3 to keep the high frequencies from being amplified/buffered by U2A. If you want to try this (it shouldn’t be necessary) , a 1nF cap would roll off at 15kHz, that would probably be a good value to start with.
Good luck…and please let me know about that manual discrepancy.
-Brach