Banishing AC Coupling - How?

[Paul Marossy]

I got my Greenlee GT-15 low voltage detector in the mail today. So I checked out my music room and it picks up stuff virtually anywhere I am in the room. Any metal objects in the room are also apparently acting like antennas for AC. Now I have a bunch of wall warts powering various musical devices in this room and a computer. My guitar, which has humbucking pickups, even picks up a small amount of hum on the neck only/bride only positions when I am using very high gain pedals. And my bass, which has active pickups in it, also has an annoying buzz a lot of the time when I want to record something (when not playing anything).

So, I surmise that these wall warts are radiating EMI throughout the room because they are in unshielded plastic enclosures, with no ground prong and everything in the room wants to pick up that EMI. My room is about 13'-0"x10'-0". It is not anywhere near an electrical panel or an air conditioning unit. No flourescent lighting, either.

So my question is, is there anything I can do to improve this situation, or I am I just stuck with these crappy wall warts making all kinds of noise in my guitar related audio equipment?

I became aware of all this by watching this video I linked in another post - http://www.youtube.com/watch?v=6ZGokkrsO_Y

[RedHouse]

Don't forget the AC wiring in the walls is not shielded either, and it (usually) makes a complete circle around the room (for outlets) and also makes a trip aroind the ceiling (lights) those sources of EMI are much greater thatn the measly wall-warts.
(some buildings the wire is shielded by conduit, but not usually in homes)

If you have never seen the electrical paths in an un-walled room before stop by a construction site and ask to have a peek, it will give you an idea of how those EMI antenna's surround you in a structure.

[Paul Marossy]

Yeah, I know how they wire houses with unshielded "romex". Electrical wiring is generally not required to be in a conduit in single family residential construction. It seems like that would eliminate some problems if it were, though.

[JKowalski]

Well, whats it worth to you? If it bothers you enough, rewire your house and faraday cage your room, buy new noiseless power supplies...

Usually people can get by pretty well by only altering things on the pedalboard end, regardless of the EM noise of your room. I think you are worrying about it a little too much - its good to worry about it a little but you aren't gonna vastly reduce the EM noise except with extreme measures... though in a studio or similar perhaps it would be worth it. There's EM radiation everywhere nowadays, might as well try to deal with it as best as we can and build our equipment to work around it. In the long run, it's a much better idea since it makes your setup more versatile since its likely that you aren't going to be confining it to the room.

[Ben N]

Transformers in your amps proably radiate a lot more than your wall warts--try placing a wah right next to an amp, then move it away.

[RedHouse]

Yeah, I know how they wire houses with unshielded "romex". Electrical wiring is generally not required to be in a conduit in single family residential construction. It seems like that would eliminate some problems if it were, though.

Only if it's the metal conduit, there are newer PVC type conduit's that don't help.

[Paul Marossy]

Well, whats it worth to you? If it bothers you enough, rewire your house and faraday cage your room, buy new noiseless power supplies...

Usually people can get by pretty well by only altering things on the pedalboard end, regardless of the EM noise of your room. I think you are worrying about it a little too much - its good to worry about it a little but you aren't gonna vastly reduce the EM noise except with extreme measures... though in a studio or similar perhaps it would be worth it. There's EM radiation everywhere nowadays, might as well try to deal with it as best as we can and build our equipment to work around it. In the long run, it's a much better idea since it makes your setup more versatile since its likely that you aren't going to be confining it to the room.

I typically don't use my pedalboard or amp when I am in my room. I use a drum machine and a Zoom 9030 to practice with headphones on, going thru a small mixer.

My low voltage detector picks up stuff on my guitar strings just like in the video linked above, but I have never gotten a shock, but the detector stops beeping when I touch the strings. I suspect this all happening because my Zoom 9030 and other things are powered by a wall wart and they really have no reference to electrical ground. It has always bothered me that a great deal of guitar effects powered by wall warts have no reference to electrical ground. It creates all kinds of audio noise. Why on earth do they design things like that?

Transformers in your amps proably radiate a lot more than your wall warts--try placing a wah right next to an amp, then move it away.

Yeah, I know. Same thing happens with a wall wart. A lot of people are mystified by their wah pedal humming a lot. I tell them to move their wall wart(s)  three feet away from their wah pedal and they are amazed that the problem went away.

Yeah, I know how they wire houses with unshielded "romex". Electrical wiring is generally not required to be in a conduit in single family residential construction. It seems like that would eliminate some problems if it were, though.

Only if it's the metal conduit, there are newer PVC type conduit's that don't help.

Yes, I know. Plastic conduit wouldn't do a thing to help.