Noise at floor level

[Ed G.]

I have this weird thing in my house with this 'plane of noise' at floor level in my house. If I put my guitar on the floor, it gets loud. Hum. I'm thinking some sort of EMF, but I have no idea what generates it at the floor level. Some sort of wiring under the house, maybe? Only cabling under the house is telephone wire and some directv coax. The phone wire also carries a DSL signal. I've got an older house, it's built up, not on a concrete foundation.

[JimRayden]

Flurescent lamps in the basement's ceiling?

---------
Jimbo

[darron]

it's not the angle that your pickups are facing perhaps also?

[Paul Perry (Frostwave)]

The mains earth - which is the same as the earth wiring on the guitar - may be at not exactly the potential of the concrete floor (and its reinforcing rods).
Back in WW1 trench warfare days,people noticed that if you stick two bayonets in the ground some distance apart & run wires to them, you can pick up stray signals. Do this in a built up area & you pick up hum (I have done this, also picked up an audio signal sent by an amplifier driving another couple of buried pipes).
I guess in the case of the guitar, it is either some capacitative pickup of ground hum, or the coils are intercepting hum radiated from stray currents flowing through the reinforcing rods.

[Ed G.]

It's not a concrete foundation, it's built up about 3 feet, a little crawl space underneath. Only wiring I can see is phone lines and directv cable. The power lines drop from the attic.

[greigoroth]

Nice explanation Paul! I got a concrete floor that also hums, I thought I was going insane before your post ed. Is it thus wise to create a pedal board where the pedals sit maybe 5 cm off the floor (like in a pedaltrain type of thing)? - am currently planning/constructing a pedal board by the way!

[gez]

Nice explanation Paul! I got a concrete floor that also hums, I thought I was going insane before your post ed. Is it thus wise to create a pedal board where the pedals sit maybe 5 cm off the floor (like in a pedaltrain type of thing)? - am currently planning/constructing a pedal board by the way!

Perhaps shield your pedal board (and ground said shield)?  Doubt it would do much, though, as it's probably the guitar's PUs that are at fault.

[DDD]

Maybe the noise is not low (audio) frequency noise, but a result of detecting RF, which in turn has its maximums and minimums spread over the certain areas?

[petemoore]

  Probably doesn't do that with the antenna trimmed, try lifting the source coils and see if that doesn't eliminate much of it.

[Plinky]

There aren't any wall warts near the pedals are there? Stupid question, but I had a large one near my wah pedal give me fits once. 

[Nasse]

http://www.elektor.com/magazines/2005/june/electrosmog-tester.57575.lynkx

[greigoroth]

Hmmm....

Could it be my wireless internet doing bad things?

Plinky: nope, no wallwarts. I noticed with the gain on that if I lift my wah pedal 5 cm from the ground there is substantially less hum. I haven't tried the other pedals to see if they are also humming more when near the floor - pedals are in the rehearsal room at the moment and I have only noticed this at home... then again, everything is noisy at rehearsal so it is possible that the hum exists there as well.

[Paul Perry (Frostwave)]

Another way to look at it: maybe your mains ground is "imperfect" (eg, resistance where the ground wire connects at teh juncttion box, or elsewhere).
this results in the entire system - ground wire, all the gear etc - having a few volts of AC on tem, relative to 'true ground".

From the perspective of the electronics, this is exactly the same as if you had a properly grounded system, and the EARTH has hum on it! (in this case, think of your concrete floor and its reinforcing as being the 'true ground'.)

[Transmogrifox]

Shag carpet?

[Ben N]

Shag carpet?

That would be likely to produce crackle, not hum, no?