Though now largely forgotten, did the Avilyn magnetic
particles represent the absolute zenith of cassette tape advancement?
By: Ringo Bones
This substance has now virtually become an “alien technology”
for those born way after the heyday of the cassette tape. But back then, this
represented the value-for-money in cassette tape technology terms when it comes
to sound quality. Besides the more expensive metal particle tapes, cassette
tapes that use Avilyn magnetic particles are probably the closest yet to
sounding like professional open-reel tapes. Stranger still, Avilyn magnetic
particle technology has its origins way before cassette tapes become a runaway
commercial success in the 1980s.
Developed as a high coercive magnetic particle developed for
sound and video recording back in 1974, Avilyn is an acicular magnetic iron
oxide on whose surface certain cobalt compounds have been adsorbed. The
coercive force of the particles is determined by the amount of cobalt and other
preparing conditions, and is controllable between 450 and 800 Oe (Oersteds).
The particles display much improved thermal stability with respect to remanence
and coercive force. The new video tape having a coercive force of 550 Oe is
compatible with chromium dioxide video tape in recording characteristic
according to measurements on a conventional video tape recorder. The head wear
rate of the new Avilyn tape is about one-fifth that of chromium dioxide tape
and is almost the same as for conventional iron oxide tape. Tape demagnetization
is not as serious as is in the case of cobalt-doped gamma ferric oxide tapes.
During the 1980s, Avilyn was mostly used in TDK’s high-bias
Type-II cassette tapes and VHS video tapes. TDK also produces Avilyn open-reel
tapes for professional studio recording use at the time when 16-bit digital
audio recording technology was still in its infancy. Sadly, during the early
part of the 21sr Century as the prices of recordable compact discs and
associated equipment came tumbling down and availability increased, everyone’s
love affair with the cassette tape slowly waned.
