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Going Topless

When changing tubes on my ARC preamps, I noticed a substantial lift in performance when the top covers were left off the units. An increase in "Air", 3D and just plain "relaxed ease" was appearent when the covers were off.
Now my particular units have Litz signal wire running from input selector and PC board to the RCA I/O jacks in the back. These bundles of wire come close to the top chassis cover, without actually touching it.
Are we dealing with "Eddy Currents" here? I have come to the conclusion that all (music)signal carrying wires, must be isolated from close proximity to metal. I have heard the same effect on ICs and Speaker wire. All of these wires appear to be well shielded and use a stiff dielectric. There must be stray Magnetic Eddy Currents at work here.
Anyone else go through this? Better yet; Can anyone explain this?
The moral, Metal and wire don,t mix...........Frank
frap

Showing 2 responses by gregm

gregm
3,021 posts
 
Shouldn't the metal cover protect against RF interference? I too have had similarly positive experience with a tube where the manufacturer advised naked if the room was "free of TV and radio interference", and covered otherwise. The sound was invariably better naked (with the occasional taxi CB adding lib to the odd concerto). The idea, as I probably don't remember it, was that the cover created a "farraday trap"(??).

Maybe Sean could throw light on my gibberish?
gregm
3,021 posts
 
Thanks for your help, Sean!
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