SOLVED Fuzzy Fox Octave Not Working

[Guitar65]

Hi. I’m hoping someone can help me diagnose this circuit. The fuzz portion works fine although there is a substantial volume increase when switching the clipping diode switch. Perhaps some one has a fix for this?
The other problem is the octave overtone. There is no difference to my ear when activating the octave switch. Admittedly I do not know much about the octave generation and how it works other than it must be filtering low tones and leaving a narrow range of high tone to pass. But how the octave tone is generated I need to research. Unfortunately there is no documentation with this pcb so I have no schematic to reference troubleshooting. I also do not know much about the Keeley portion of the effect.
Thanks

 

[ICTRock]

for best ring modulation results the diodes should be matched within 10mV of each other when measuring forward voltage, which is difficult with germanium diodes but not impossible. I usually recommend schottky diodes in their stead because they more easily match and their curve is more consistent as well.

outside of the technical, the effect is more pronounced on the neck pickup and playing above the 12th fret. if that particular playing style still isn't generating any ring modulation it's time to revisit the technical issues

 

[Guitar65]

Thank you. I’ll look at the other diodes I have on hand and see if there’s a better matching pair.

 

[Guitar65]

I just looked at the only other octave fuzz I’ve built and it used BAT45 Schottky diodes.

 

[ICTRock]

I typically use 1n5817 because they show up a lot in reverse polarity protection on PPCB builds but any schottky will do so long as you can get them fairly well matched.

 

[Guitar65]

Thanks

 

[pricklyrobot]

My experiences with the Foxx Tone circuit are:

• a Danelectro French Toast
• a GGG PCB w/ 1N34A’s from EBay that I made no attempt to match - wouldn’t have known how or why to, 15 years ago when I built it

In both cases the octave is really pronounced and un-subtle (as compared to something like a Superfuzz) and doesn’t require any particular attention to pickup selection or playing technique to be able to hear.

Assuming the Fuzzy Fox is a pretty similar circuit re: the octave part (there’s no parts list or schematic currently available to view), I’d go through the normal troubleshooting stuff (check/reflow your joints, run through it with an audio probe, etc) before you start swapping parts.

Q2, D1, and D2 should be your octave section, I think…

 

[Guitar65]

Thanks!

 

[Guitar65]

Replaced the ge with shottky after normal troubleshooting and it’s much better.