How to shield a humming transformer

[yeeshkul]

Guys what is the best material to shield off a humming transformer?

[EBK]

Is it humming because the windings are wiggling?

[GibsonGM]

There's theory, and then there's 'field performance'.   Shielding it may or may not result in noise reduction.  Like Eric is asking..it is 'vibrating'?   

"Material" to shield with...anything that will conduct its magnetic flux to ground...

Are we sure it's the actual transformer causing an issue, and not the wires to/from it being routed poorly?  Tell us more about the problem if you could...

[karbomusic]

"Material" to shield with...anything that will conduct its magnetic flux to ground...

MU Metal.

[EBK]

You may need to think mechanical dampening rather than electromagnetic shielding....

I'm expecting (hoping for) Paul R. to share some wisdom on this. 

[digi2t]

I'm expecting (hoping for) Paul R. to share some wisdom on this. 

"Yeah, I remember once, one of my tractors had a transformer hum..."

[bluebunny]

Q. How do you stop your transformer humming?

A. Give him the words.

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Ooops! Wrong thread!   

[yeeshkul]

Guys thank you, it hasn't happen yet, but i am building a transformer fed guitar effect, and since the transformer will be placed quite close to the audio path, i am expecting troubles on the way.
I will tell you more when i actually wire it up.

[PRR]

Distance is by far the best shielding.

[wavley]

Distance is by far the best shielding.

Paul is right, Mu metal is the best when distance is not practical, but it's expensive and needs to be heat treated after it has been bent.  I've actually had pretty decent luck using metal junction boxes from Lowe's, aside from exotic things thickness and magnetic permeability are your main things you're looking for, even aluminum can be a good shield when thick enough.

[Rob Strand]

The location and orientation can make a big difference with a conventional transformer.  (And distance as PRR pointed out).

A properly implemented magnetic shield is tricky (and not economical in production).

Maybe consider a toroid or an external plug pack.

Think about how many commercial devices you see with magnetic shielding?

[amptramp]

You could always put the transformer on the outside of the box so the box can shield everything on the inside.  Some of the small tube amps are built like that.

[EBK]

My vote is toroidal xformer.