IC Muff Fuzz Issue - Will an Enclosure Fix Excessive Noise?

[ElectricDruid]

Got it. Is it as simple as grounding that capacitor or will it's position have to change? I'm using the vero layout below and I can handle just grounding it (+ to pin 3, - to ground), but if it needs to be in a specific spot in relation to R3 and R5, I'm having a hard time figuring out where it should be relocated.

Yes, its position will have to change. It needs to go in parallel with the other 680K resistor, instead of the one up to 9V.

So it'll be placed with the positive end where the negative end currently is, and the negative end down to ground on the bottom row.

[antonis]

This: 



P.S.
Off topic but, either way C2 is fitted, it equally serves as 4.5 Vbias "stabilizer" and AC ground point..
(considering +9V power supply internal resistance negligible..)

[ElectricDruid]

Exactly that. Thanks Antonis.

[Fancy Lime]

I suspect that the old original units may have had the cap go to the positive rail. Most likely for reasons of layout convenience or simply 'cause why not. If you only ever run it off a battery, there is essentially no difference. It only starts to matter when the impedances of the rails are different, which can be the result of power supply noise filtering. If that is the case, we normally try to keep the impedance of the "designated ground" (negative in this and most other cases) as low as possible, while that of the "designated supply rail" (here and usually positive) may be higher. In practice it hardly ever makes an audible difference in audio circuitry. It's mostly just "best practice" to only connect stabilization and AC dumping caps to ground. As soon as you start dealing with high gain or RF, things become a little more complicated. So it's always good to follow best practices as a habit, even when it may not be strictly necessary.

Anyway, carry on,
Andy

[nerdbot]

Thanks so much for the help everyone. I grounded the cap and went with 100u, mostly because I only bought a single 10u for some reason and the legs were too short to reposition. Unfortunately, it didn't resolve the gating with other op amps, but possibly made the noise/decay slightly better.

I think I'm moving on! I'll leave the gating issue to others, but it sounds great with the TL072. I'll report back once I put it into an enclosure and try to provide some audio clips.