Fuzzdog MFZ1 build - ground noise through output?

[MechaGodzilla]

I knocked this one up last night and it's really noisy. I tested it before housing it and I thought "oh maybe it's just picking up noise because it's not yet inside a metal box" but it's noisy even after boxing it up, even on a battery (putting out ~8.6v).

I tested continuity at a few points and it seemed the ground might have been connected to the output but I couldn't replicate that when I checked about an hour ago. I might go back and redo the ground connections at the jacks with a bigger iron tip coz they're not great at the minute. I was super careful with the diodes and IC (how do you even test an IC with a multimeter?).

Any ideas folks?





Kit instructions

[Ben79]

Output would probably see continuity with ground if your volume happened to be on minimum.

[MechaGodzilla]

Output would probably see continuity with ground if your volume happened to be on minimum.

Yeah, I think that's what I'd done the first time I checked. I've still got no clue why it's so noisy.

[MechaGodzilla]

Huh. Sounds fine off an adapter

[Ben79]

Try a fresh battery and see if voltage is the issue?
Check your battery joints?

[eatyourguitar]

ground noise is an oxymoron since all unbalanced signals reference ground. the sound of ground on both the tip and sleeve is silence. you are probably talking about 60Hz hum being inducted into an antenna and amplified by a gain stage. I guess maybe I understand what you are trying to say. it is a common misuse of the term since most people with ground loops have the different potentials on the sleeves of unbalanced gear transmitting 60Hz hum super imposed on the signal. here is a check list...

* do all your unbalanced sleeves have one path to ground?
* do your sleeves have equal resistance paths to ground?
* do your sleeves have reasonably low resistance to ground? (short cables, not broken, reasonable gauge wire)
* are all of your cables and boxes shielded by properly grounded RF screens? (see the first 3 things)
* are you using fluorescent lights in the room?
* if your gear has a 3 prong plug, is there more than one piece of gear with a 3 prong plug?
* if using a 3 prong plug, is your ground hot? are your grounds looped through the wall AND the audio sleeve?

[MechaGodzilla]

I fixed it