[Mark T. Montgomery]

Hey guys, I've heard before that with certain types of metal you can easily shield the components in your amp to get improved sound.  This is supposedly due to reduced interference between the components themselves?  My question is what type of metal should I use, what components other than the transformer shoud I shield, and how much of a difference will this make?
I've read that this is a trick that several of the best amp makers use?

[Gordy]

Hi Mark,

Mu metal, a high nickel content alloy, is the best, though rather expensive http://www.lessemf.com/mag-shld.html .  Mild steel works really well, but don't use stainless!  I found out the hard way that copper isn't very effective against EMI, though good for RFI...  ERS paper could be used in addition to the steel, BPT uses it in their signature power conditioner.

[Lost81]

Hi Mark,

As Gordy stated, mu-metal works well. I think it is susceptible to rust though.

Michael Percy sells 2 other types of shielding material:

TI SHIELD: Unique composite shielding material from Texas Instruments for blocking EMI & RFI interference. Conventional
shielding materials excel either in electrical conductivity or magnetic permeability, but not both. Steel is not conductive enough
to be effective at blocking high frequencies, while copper and aluminum are not effective at absorbing low frequency EMI. No
single material met both of these requirements until TI developed this copper/alloy 49/copper composite material. TI Shield is
effective from below 10Hz up to 10GHz and is currently available only in .014" thickness. Counterpoint utilized similar technology
in construction of their chassis' and found significant audible benefits were to be derived from surrounding audio circuitry
with materials that shield against both EMI & RFI. MicroSorb (pg. 18) could be used to adhesive back this material and provide
mechanical damping of the chassis as an additional benefit. Unlike Mu-Metal, this material may be cut and bent into convenient
shapes without requiring annealing to restore its shielding properties. 12" x 12"/$27.95, 12" x 24"/$54.50

Stillpoints ERS EMI/RFI Suppression Cloth: In appearance a grey cloth like material impregnated with carbon fibes
that are wash coated with metals in a proprietary process. This material not only shields from and reflects EMI/RFI, but absorbs
it, so merely laying a sheet on top of, or wrapping, noise emitting components (anything digital, AC junction boxes, power supplies,
transformers) can have dramatic results. Even speaker drivers, crossovers, and turntable platters may benefit with this treatment.
Users have reported spectacular reductions in glare, hash, background noise, etc. The polyester fabric will insulate the core
of ERS, to some degree, but can be easily penetrated with shape edges. Caution should be exercised when used in close proximity
to circuitry. See Positive Feedback & Stereo Times articles. 8.5" x 11" sheets @$19.95 each
Free UPS ground shipping (48 states)
for any order containing 2 sheets+ ERS.


-Lost81

[Mark T. Montgomery]

Thanks guys, now all I need to now is what components to shield and how cost effective this is?  How of a difference should I expect from this mod?

[Gordy]

Good point Benny, I need to go back and rust proof that mild steel!

I've shielded transformers mainly.  In my amps, tuner, cdp's and dvp's.  I used steel (free) and ers, which I get from Mike at http://www.cryotweaks.com/index.shtml, as he's a member/contributor here   I think it's a very cost effective tweak even with using a double layer of the ers outside the steel.  I've also used the ers around the dig. section of my cdp's...  I personally stay away from anything analog/line level.

I did all my shielding back when I was moding a Carver amp, so I can't really comment on individual contributions, found it to drop the noise floor which in turn allowed better detail in my components/system.  

All the best, Gordy