Monday, May 25, 2009

Non-print equipment & services: Cassette tapes

The earliest analog cassettes used ferric oxide tape, now referred to as “normal” or “Type I” tape. Many recordings are designed to record only on Type 1 tape. If you can’t find any switch or indicator on your recorder showing what type of tape it’s supposed to use, assume that Type I will work in all machines.

Many models can also use Type II cassettes, referred to as “chrome” or “high bias” tapes. Some recorders can recognize automatically whether an inserted tape is Type I or Type II. On other recorders you have to use a manual switch to set the recorder for proper operation with the tape type you’re using.

The highest quality cassette tape is called metal or Type IV (the short-lived Type III, or ferrichrome, was a blend of ferric and chrome oxides). Metal cassettes require much more bias current for proper recording, so using metal cassettes can reduce battery life in portable recorders by a third or more. But their sound quality, when used with a recorder that can drive them properly, is excellent.

Shell construction
A good shell provides environmental protection for the tape, keeps it packed smoothly, provides a low-friction path for the tape to move along during record and playback, and doesn’t warp in high temperature conditions. Shells made to closer tolerances for all these factors cost more money, but they’ll yield better sound quality and longer life for the cassette.

Many cassette shells are glued together or “welded” with ultrasonic vibrations. But the better shells are assembled with five screws, one at each corner and one in the middle. If an irreplaceable recording should ever suffer a jam or snap the tape, you’ll discover another advantage of screwed shells: you can disassemble the cassette, remove the tape, and splice or straighten it. Then you can reassemble the tape in the same cassette, or (if a damaged original shell was the problem) transplant the valuable tape to a “donor shell” from another cassette. In contrast, opening up a welded or glued shell requires prying and cracking which can further damage the tape.

For best results with cassettes, follow these guidelines:

Don’t use C90 or longer length cassettes. The tape in all cassettes up through C60’s (30 minutes per side, one hour total) is the standard thickness tape. The tape in C90’s and C120’s cassettes is thinner, and more vulnerable to damage, print-through and other problems.

If you reuse tapes for several recordings, bulk erase the cassettes to get rid of old recordings before making the new ones. This is particularly important if the cassette may get used in several different recorders: unless their heads are aligned exactly the same, one recorder may not be able to completely erase an existing recording made with another recorder.

If you intend to save a recording, break out the record inhibit tabs on the rear spine of the cassette. This will protect the cassette against accidental erasure.

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