Demagnetizing

[rollo]

  So obviously over time we build up magnetism in our components. If we UNPLUG them for several days will not the magnetism wear off ? How long can a piece of metal stay magnetized ?



charles

[_Scotty_]

From what I can glean from the scientific literature on magnetism only ferromagnetic materials can be magnetized. They require a constant magnetic field from a permanent magnet or a magnetic field from a constant non-fluctuating DC power source. Brass, copper and other non-magnetic materials will not be readily magnetized by a low level musical signal as is found in the circuitry of small signal devices up stream of a power amp.
I would be very reluctant to attempt to deguass any small signal circuitry due to the possibility of damage due induced currents of greater amperage than the device or circuit was designed to handle. This damage would be analogous to the type of damage seen from EMP which tends to fry things that are not hardened in some way.
As far as how long something might remain magnetized, I have screw drivers that I magnetized with a permanent magnet years ago and they are still magnetized.
Scotty

[rollo]

  Thanks Scotty.

charles

[BobM]

There has always been controversy about degaussing phono cartridges for the reasons you state above Scotty. They are delicate instruments with a magnetic field and very small tolerances. The possibility of screwing them up far outweighs any suspected benefits IMO.

As for demagnitizing CD's or vinyl records, I've tried it and heard nothing different. Logically it would make sense that it shouldn't have any effect, but then we all know that logic isn't always correct in audio, and we also know there is a lot of snake oil out there too. YMMV.

[P.I.]

There has always been controversy about degaussing phono cartridges for the reasons you state above Scotty. They are delicate instruments with a magnetic field and very small tolerances. The possibility of screwing them up far outweighs any suspected benefits IMO.

As for demagnitizing CD's or vinyl records, I've tried it and heard nothing different. Logically it would make sense that it shouldn't have any effect, but then we all know that logic isn't always correct in audio, and we also know there is a lot of snake oil out there too. YMMV.

Stay tuned about the CD thing...