John Sayers' Recording Studio Design Forum Archive

Hi,

This post is about the ground hum (pretty sure it is anyway) that i am getting from my studio, due to the fact that over head power lines run over it.

Studio details:

Location - England, Essex

Dimensions - 3m x 4m -

40mm Think pine walls - 100mm of rock silk - Carpet. Pine roof 20mm - 100mm rock silk - Fabric

Wiring:



The power is in plastic conduit and is earthed though a fuse box, the lighting and plugs are on their own fused circuits. The cable is however not shielded which had i of know this would of happened it would have been.

I thought of maybe laying chicken wire over the roof and grounding it but dont know if it would do any good.

The intensity does vary during the day which makes me 99.999999% sure its the over head power lines.



This is very frustrating as i am sure some one you might know, any help will be greatly appreciated.

Thanks

Matt

Is your fuse box earthed at the shed? With a ground stake
Can you star ground the GPO's now? How big is your fuse box?

No, the shed it grounded at the house ground. The fuse box is a 16A.

I did a test when I took all power out from the shed a used a battery powered amp and still the hum existed. Also when I turn direction the intensity increases depending on which way I face.

When i run a piezo pickup I do not get any hum so its on the magnetic ones that are affected.

I do believe it is the Mains power running over head as they are only 10ft off the roof, which supplies the whole road, so they are quite high currents.

Do you have any recommendations on shielding? I am thinking on laying Fine Steel Mesh or steel sheet roofing over the whole roof and grounding it. Time to hit the bank.

Thanks

Matt

"The interference may be coming from electrical power lines. The power grid that supplies your neighbourhood may prove to be the source of the interference. Contact your electrical utility to resolve the problem."
that from a canadan website.
Why don't you give your supplier a call.
or
"Adding on-board EMI filters or special layout techniques help in bypassing EMI or improving RF immunity"- wiki

Matt - is the hum affected by you touching the strings?

John Sayers wrote:Matt - is the hum affected by you touching the strings?

no, i have also tried touching other metal stuff no joy though. I am thinking of rewiring with shielded mains cable, not sure if it will help though.