Shielding versus damping.

Posted by Al Sekela (A) on December 12, 2007 at 16:14:30

In Reply to: Thanks for your kind reply. Some more questions posted by diyaudiophile on December 12, 2007 at 00:44:29:

Shielding reflects energy, while damping absorbs it. Contrast a mirror with a piece of black velvet. If you were to build a dark room, would you line the walls with mirrors or black velvet?

TI-Shield in this application is acting as a damping material. RF noise travels along wires and through components as electric and magnetic fields. The center layer of TI-Shield is a high-permeability alloy that provides a low-reluctance place for magnetic fields to go. Since these fields are time-varying, they induce eddy currents in the copper outer layers. The copper has some resistance, so these eddy currents dissipate energy from the RF noise.

A shield, such as a thick piece of copper, would reflect the RF energy much more than it would absorb it. Shielding, to be effective, requires complete coverage of the circuit with the shielding material, and then you still have the RF energy bouncing around inside.

Damping, on the other hand, does not require complete coverage. This is why Chris' design works. I should also point out that I do not know if the cylinder shell of TI-Shield is optimum for the AC damping networks: it may be overkill, or too little. It is clear, though, that you do not want the TI-Shield piece to be able to vibrate in response to room sound. Putting a vibrating piece of high-permeability material next to a circuit invites severe microphonic behavior. The Microsorb or equivalent acoustic damping material is very important.

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Follow Ups Full Thread

Topic - Validating use of TI-Shield on R-Cs (long) - bartc 20:14:18 12/02/07 (29)

Continued adventures & a pic - bartc 07:33:05 12/09/07 (10)

Is the TI shield easy to cut and shape ? - diyaudiophile 23:35:04 12/10/07 (9)

A 40-watt soldering iron is good for TI-Shield. - Al Sekela 15:30:12 12/11/07 (1)

Thanks AL (nt) - diyaudiophile 00:15:35 12/12/07 (0)

OK, answers where I have them - bartc 05:58:32 12/11/07 (6)

Thanks for your kind reply. Some more questions - diyaudiophile 00:44:29 12/12/07 (5)

Shielding versus damping. - Al Sekela 16:14:30 12/12/07 (2)

RE: Shielding versus damping. - diyaudiophile 23:25:50 12/12/07 (0)

Thanks for the clear explanation of the difference, Al! - bartc 17:04:18 12/12/07 (0)

I asked the same questions with no satisfying answer - bartc 05:42:02 12/12/07 (1)

RE: I asked the same questions with no satisfying answer - diyaudiophile 23:16:34 12/12/07 (0)

Thanks, Bart. - Al Sekela 21:10:35 12/03/07 (6)

Additional clarifications for y'all - bartc 21:51:58 12/03/07 (5)

RE: Thanks Guy's ! - benie 01:44:55 12/04/07 (4)

Clarifications. - Al Sekela 13:39:39 12/04/07 (1)

RE: Thanks AL (nt) - benie 02:07:10 12/07/07 (0)

I still do, but not sure if Al does now - bartc 05:40:12 12/04/07 (1)

RE: Glad to hear your getting the great results. (nt) - benie 02:10:12 12/07/07 (0)

Nice report - RioTubes 19:20:40 12/03/07 (1)

Try it, you'll like it too, I bet! nt - bartc 19:48:15 12/03/07 (0)

One more point that I forgot to mention... - cdc 23:14:05 12/02/07 (7)

I do use the 12 AWG - bartc 06:18:18 12/03/07 (6)

RE: I do use the 12 AWG - cdc 10:29:35 12/03/07 (5)

Good ideas, I'll try it and report back. nt - bartc 12:32:56 12/03/07 (4)

Excellent. By the way... - cdc 14:29:43 12/03/07 (3)

Jeez, Chris (and Alan M) are right! - bartc 20:02:25 12/04/07 (2)

Bro, I experimented for about three months... - cdc 22:41:38 12/05/07 (1)

You did indeed tell us all that! - bartc 06:00:30 12/06/07 (0)

I did not think about this but.... - cdc 22:01:34 12/02/07 (0)

Follow Ups

Shielding versus damping. - Al Sekela 16:14:30 12/12/07 (2)

RE: Shielding versus damping. - diyaudiophile 23:25:50 12/12/07 (0)

Thanks for the clear explanation of the difference, Al! - bartc 17:04:18 12/12/07 (0)

Shielding versus damping.

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