Noise issues when powering two circuits on breadboard

[ramonolague]

Hello,
I’m running into noise issues while prototyping two circuits on the same breadboard. I’m trying to combine a Ritual Fuzz (Colorsound One Knob Fuzz) and an Acapulco Gold into one enclosure, with some mods to both circuits plus an input gain pot.

The issue is that I can’t power both circuits at the same time without introducing noise and squealing. If I power only the Ritual Fuzz, it works perfectly. But the moment I power the Acapulco Gold circuit — even without routing audio through it — the fuzz starts producing artifacts: a faint background squeal, ring-mod-like sounds as notes decay, and a quiet high-pitched hum when the guitar volume is rolled down to zero. As soon as I disconnect power from the second circuit, everything goes back to normal.

I suspect it’s a power-related issue, but I haven’t been able to solve it. I’ve tried adding caps to ground and splitting the power rails, but either I’m wiring something incorrectly or overlooking something obvious. Any help would be greatly appreciated.

 

[Cybercow]

IMO: Typical breadboards have no ground plane, and with no large ground surface to capture stray emissions, breadboards are notorious for noise with dirt circuits. Double dirt circuits will often quiet down once enclosed in a properly grounded enclosure.

How does the Acapulco Gold do when the Ritual Fuzz is not powered?

 

[genXslacker]

How does the Acapulco Gold do when the Ritual Fuzz is not powered?

If it doesn't make noise on its own, I'd try buffering the signal out of the fuzz and into the AG. I'm know EE, so it seems like magic when a buffer clears up a squeal I haven't been able to eliminate any other way.

 

[swelchy]

Heck.. even in an enclosure the Acapulco is a super noisy pedal..... It's literally designed to massively be distorted... Nothing subtle or studio quality about it... pretty sure that pedal is literally made to bang power chords and scream lyrics about fighting the system.

 

[BuddytheReow]

I second what Cybercow has said. You've also got a unique issue with the one knob fuzz (and other fuzz face variants) that is probably the main culprit. In these circuits, the audio path is thrown into the DC path and that's probably what you are hearing when both circuits engaged. See below schematic. IMO, even if committed to solder, you'll still probably have this issue whether PCB or stripboard unless you can do something clever such as a buffer(?) or two separate power supplies.