Noisy only when on the floor

[SuperGeo]

Hi guys

I've built an sansamp gt2 clone in a plastic enclosure and shielded it with aluminium foil. It worked well and the noise wasn't annoying but when I get it on the floor a Hum noise start to appear. Just raise up the pedal from the floor and it goes away.

There isn't any mettalic part touching the floor. I have really no idea why is it happening 

I'd appreciate any help

[bioroids]

That happened to me a few times, but always dissapeared when using a metal box. I think the most important part of the shielding is the bottom of the box. You should check if the aluminum foil is covering the whole box and if it's properly connected to ground.

It seems that at some places there is a lot of RFI running thru the floor (it can affect the cables too), maybe because of wires or pipes running there and acting as antenna?

Luck

Miguel

[mac]

The floor has a magnetic permeability greater than air so near the floor there is more density of EM waves.

mac

[SuperGeo]

That happened to me a few times, but always dissapeared when using a metal box. I think the most important part of the shielding is the bottom of the box. You should check if the aluminum foil is covering the whole box and if it's properly connected to ground.

It seems that at some places there is a lot of RFI running thru the floor (it can affect the cables too), maybe because of wires or pipes running there and acting as antenna?

Luck

Miguel

yeah you're right I checked here and the bottom of the box was not connected to the rest of the shielding. Solved it and it's really quiet.

Thank you very much 

[SuperGeo]

The floor has a magnetic permeability greater than air so near the floor there is more density of EM waves.

mac

yep I didn't know that... that's why my stompbox was less noisy in the air

[bioroids]

Cool!

Miguel

[Paul Perry (Frostwave)]

This 'floor' business has made my day! I have a friend who is into very low frequency (VLF) and audio frequency electromagnetic signals (for 'found sound' tracks) & I'll ask him to start checking out floors!! Gives a whole new meaning to the term "noise floor".

[mac]

One important thing...
Remember to sweep your floor. It wont stop the noise but your stomp box will keep on shining 

mac