Magnetic Tape
by Michael N. Geselowitz
The recent announcement that Quantegy Inc. — the successor to
Ampex Corporation — was closing the last magnetic tape
manufacturing plant in the United States brings to an end a
technological era. The idea of recording and playing back sound
by recording a magnetic signal on a conductive medium was first
thought of by American Oberlin Smith in 1888, and the first
practical device to do so—using wire as the medium — was Danish
inventor Valdemar Poulsen’s Telegraphone, patented in 1898 (Poulsen
also invented the arc-transmitter,
an IEEE Milestone).
For the next few decades, although work was also carried out in
the United States and the United Kingdom, among other places, the Germans led the
efforts to improve magnetic recording. AEG developed the
Magnetophone, and improvements in the chemical engineering of
polymers allowed its partner BASF to ship the first magnetic
tape in 1935 — a foil of cellulose acetate coated with a lacquer
of iron oxide bound with additional cellulose acetate. Most
developed nations continued to work on magnetic tape for
commercial and, with the approach of World War II, military
applications.
During the War, the Allies became aware of the German
superiority in this technology. As U.S. forces advanced late in
the war, a young technician from the Army Signal Corps, John T.
“Jack” Mullin, was assigned to capture and analyze enemy radio
equipment. He stumbled upon an advanced Magnetophone, and U.S.
work soon progressed in this area.
According to one popular story, in 1945, General Dwight D.
Eisenhower wanted to record a message to the German people,
which he did using captured German tape. However, the tape had
not been completely erased, and Hitler’s voice, so the story
goes, could be heard
intermittently along with that of Eisenhower. Eisenhower ordered
that no more captured tape could be used, and ordered Major John
Herbert Orr to use captured German scientists to set up an
American tape manufacturing facility.
Afterwards, Orr returned to civilian life in the United States where he
went into partnership with Alexander Poniatoff. Their
company — Ampex — began producing magnetic tape and magnetic
recorders (German patent rights on the recorders had been seized
by the U.S. Alien Property Custodian).
Meanwhile, Mullin had also returned from the War, and in
1946 demonstrated the advanced Magnetophone to a meeting of the
IRE, predecessor to the IEEE. There,
according to Mullin's own account, it created quite
a sensation. Word got back to Bing Crosby, who was a pioneer in
the area of entertainer-as-entrepreneur (think Oprah Winfrey
today). With Mullin as a consultant, Crosby began to use the Magnetophone to record his radio programs. Soon Mullin entered
an arrangement with Ampex to supply the equipment and recording
medium, and the company and the technology took off.
The full Bing Crosby story will make for a good “Engineering &
Pop Culture” piece in this space some day. The important fact is
that magnetic tape became a crucial recording medium for the
birth of the information age, used for video as well as audio,
in formats such as cassette and 8-track, for sound recording in
motion pictures (replacing optical sound tracks), and eventually
for digital recording, including computer memory.
There were
many other players around the world: 3M in the
United States; a reformed BASF in Germany, Philips in the Netherlands;
and
Sony in Japan. Ampex always remained a leader, and in 1995,
Ampex successfully spun off its media division as Quantegy.
Over the past few decades, digital recording has all but
completely supplanted
analog recording. Various new media, including those that employ
lasers, are now more widely used to record digital signals. Although magnetic tape will continue to be used for niche
applications, it is no longer as ubiquitous as it once was. We tip our hat to
Quantegy and
the closing of another chapter in electrical history.
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