Given their propensity to go dull whenever they are
accidentally placed near magnetic objects – even magnetic screwdrivers - why
aren’t cassette tapes provided with inherent magnetic shielding?
By: Ringo Bones
Unlike your Barclay-Crocker prerecorded Open Reel tapes that
came in mu-metal cans as standard, prerecorded cassette tapes back in the 1980s
and even well into the 21st Century doesn’t come with protection
against erasure when accidentally placed against a strong magnet like refrigerator
magnets and electric guitar pickups and electric bass guitar pickups. And if
you Google search cassette tapes that are magnetically shielded, you are
directed into Google’s lists of invented patents stating that the tiny nickel
plated piece of steel behind the pressure pad functions as a “magnetic shield”
for the cassette tape. Given that this concern was largely ignored by the
leading cassette tape manufacturers during the format’s lifetime, is it even
possible to magnetically shield cassette tapes against erasure and loss of high
frequencies when accidentally placed closed to magnetic screwdrivers, fridge
magnets, and electric guitar and electric bass guitar pickups?
Back in 1979, the world’s leading cassette tape manufacturer
TDK released their MA-R series of cassettes and they were the top of the line
of the company’s Type –IV metal particle cassettes. The tape formulation used
is based on TDK’s patented Finavix particle. It’s very heavy and its metal
shell construction – later revealed to be an aluminum-zinc alloy – has the
potential to be made with an actual mu-metal alloy capable of actually provide magnetic
shielding for the cassette housing instead of just a vibration reduction
measure. Sadly, given that these were top of the line in the TDK’s range of
cassettes, they were also very expensive. From the 1980s through to the 1990s,
TDK’s MA-R series of metal particle cassette often carry a retail price of
around a dollar and a half to two dollars less than a price of a compact disc - which for all intents and purposes just too high a price to pay for a blank cassette tape.
This largely explains why I totally abandoned prerecorded cassette tapes in the
mid 1990s when the “relatively affordable” Marantz CD-63 Ken Ishiwata Signature
model entered the market.
