A Maxell HE-44 cassette type demagnetizer
A cassette demagnetizer is a device that removes the
magnetic
Magnetism is the class of physical attributes that occur through a magnetic field, which allows objects to attract or repel each other. Because both electric currents and magnetic moments of elementary particles give rise to a magnetic field, m ...
field that accumulates during the use of
audio cassettes in
cassette deck
A cassette deck is a type of tape machine for playing and recording audio cassettes that does not have a built-in power amplifier or speakers, and serves primarily as a Transport (recording), transport. It can be a part of an automotive entertai ...
s.
The passage of magnetically charged tape over the metallic parts of the tape deck imparts a magnetic polarity that can reduce fidelity in recording and playback. Demagnetizers (also called ''
degaussers'') remove this polarity.
Demagnetizers of the ''cassette'' type resemble cassettes and contain
circuitry to demagnetize
tape heads. Demagnetizers of the ''wand'' type demagnetize anything that they touch, including tape heads and
capstans. The wand's advantage lies in its demagnetizing other metal parts of the tape path, not just the heads. Used carelessly, it can increase the magnetization of the heads; if used too close to tapes, it can erase them. Both of these types of demagnetizer contain electronic circuitry and require a power source (either a
battery or a power cord).
A third design consists of a cassette shell with a head cleaning tape wound on the spools and a magnetic disc mounted above the head cleaner tape. When the deck "plays" the cassette, the tape cleans the heads and simultaneously the magnet rotates, creating the alternating magnetic field required for demagnetizing.
Some cassette decks demagnetize themselves. These work by feeding the record head a high-frequency signal, whose amplitude is great at first and then is reduced to zero over a few seconds.
References
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Audio storage