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DILAPIDATED EARLY TAPES CAN BE RESTORED - ONLY FOR AN HOUR - AND RECORDED ON CD

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To the delight of serious collectors, older recordings of outstanding musical merit are constantly being reissued on CD. Yet the process of transfer to the new digital format led to a sad discovery. Many priceless master tapes of yesteryear had deteriorated, seemingly beyond hope of restoration.

When fetched from their storage vaults after 30 or 40 years, the tapes containing the original recording proved no longer playable.Unless a mint-condition LP pressing could be found, no satisfactory transfer to CD could be accomplished, and in all too many cases, the musical legacy of an incomparable artist seemed forever lost.

The tapes so fatally affected stemmed mostly from the early period of tape recording - the years following World War II.

After its initial development as a part of German wartime research, magnetic tape was quickly adopted as the preferred recording medium by record companies throughout the world.

By 1950 it had replaced the old wax or acetate platter in almost every studio.

However, nobody realized that the tapes of that era were chemically unstable and thus vulnerable to the passage of time.

The adhesives binding the magnetic particles to the plastic backing slowly leached out in the intervening decades, leaving the magnetic layer brittle and flaky.

Such tapes would instantly self-destruct when engineers tried to copy them onto CDs. The loosened magnetic particles would come off, clogging the playback head of the tape recorder while leaving the tape itself denuded of the music. As a result, many transfer projects had to be abandoned.

But a way to rejuvenate those moribund tapes has now been discovered. Agfa Corp., one of the leading manufacturers of professional recording tape, developed a process that brings defunct tapes back to life for a short time - a single hour.

After that, the tape reverts to its former state of dilapidation. Yet during that single hour of resurrection, the musical content of the tape can be rescued and recaptured in digital form.

Agfa explains that the brief rejuvenation involves baking and subsequently cooling the old tape under carefully controlled conditions.

The object is to melt those clotted and hardened adhesives so they flow freely to redistribute themselves evenly along the tape surface and once again bind the magnetic particles firmly enough to prevent any shedding during replay.

The main trick is to do this without displacing the tiny magnetic particles from their exact positions, which represent the shape of the sound waves. Just how this is done Agfa won't tell, but the process has now been made available as a custom service to record companies as well as to the archivists of broadcasting organizations.

The process was developed jointly at Agfa research laboratories in Munich and in the United States and has proven both reliable and effective.

"We haven't yet met a tape we couldn't restore," claims John Matarazzo, technical manager at Agfa's U.S. headquarters in Ridgefield Park, N.J.

At this point, nobody can tell what nuggets of the musical past, formerly inaccessible, might be reclaimed for contemporary listeners by the new method. But in all likelihood, listeners have a treat in store.

As W.H. Auden put it, "For many of us, some of our most important `new' experiences are discoveries about the hitherto unknown past."