RFI/EMI Shielding, is it necessary?

[mkruger]

Iv'e always assumed when building my tube mic pre that using an RFI shielded case was necessary becuase the components/wires inside are not shielded. I've been using Par-Metal 14U series shielded cases for this. I noticed they also make a table top case specifically for amplifier and hi-fi audio projects that's not shielded. Both cases I've mentioned are made from the same aluminum-alloy.

So this made me think... Is the shielding necessary? Or should I be asking does metal, such as aluminum, provide enough shielding on it's own? Thanks for your help!


-mike

[runebivrin]

A metal box forms a Faraday's cage, which blocks any RFI quite well.

Near as I can tell from Par-Metal's web site, the 14U case is designed to have no openings what so ever, with overlapping edges, to completely block any form of RFI.

I think you'll find the table top case work well enough for these purposes. Particularly since you're building a tube thingy, which could probably use the ventilation. You can always cover the vents with a fine metal mesh if RFI should prove to be an issue.

Rune