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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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In Reply to: magnetic shields... posted by DC STEVE on June 29, 2007 at 13:38:23:
Materials with high permeability are usually nonlinear. If they are close to audio equipment or cables, they will interact with the magnetic fields associated with the audio signal with their nonlinear character. They will alter the tonal character of the system through the distortion they add.
This material would be useful to control magnetic fields from non-audio appliances.
Shielding is usually done with metals such as aluminum or copper, that have permeability close to unity. Magnetic fields pass through these shields, so routing a shielded cable next to, say, a power transformer, may result in a lot of hum induced into the cable. If I had this problem, I would use small amounts of the magnetic shielding material close to the transformer, and try to keep the cable as far away from the magnetic shielding material as possible.
An exception is the specialized material used in Highwire Power Wraps and as the RF damping material on Skywire cables. This has high permeability but is designed to not interact with signals below about 1 MHz. It contains materials that dissipate RF energy.
There is an important distinction between shielding and damping. Shielding reflects electrical noise energy, in the same way that a mirror reflects light, while damping absorbs energy like black velvet absorbs light. Controlling noise in audio systems requires both shielding and damping to be applied judiciously, and with attention to the side-effects.
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Follow Ups
- Better to keep this away from the audio system... - Al Sekela 12:58:34 06/30/07 (0)
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