Next: Digital Audio Tape (DAT)
Most everyone is familiar with standard cassette tapes such as those
used in consumer hi-fi gear. Analog tape works by magnetically
encoding a representation of an audio signal on a long strip of
metallized plastic. This strip of plastic moves past what is known as
a head inside of the tape deck. Heads are responsible for
converting the magnetic energy into electricity for playback, and
vice-versa for recording. Other components inside of the deck help to
keep the tape moving past the heads at precisely the correct speed.
It should be noted that practically every component in a tape deck
physically touches the tape, thus causing wear and tear on the tape
While it can be argued that cassette tapes reproduce sound accurately,
they are plagued by several other problems that reduce audio quality.
Tape suffers from hiss (high-pitched sound that sounds like steam
spraying from a pipe), dropouts (periodic loss in audio level), and
wow and flutter (periodic changes in pitch due to the
mechanics of the tape deck or the stretching of the tape itself).
Expensive tape decks get around many of these problems with special
electronics and high quality mechanisms.
Tape is not an especially robust medium. Inexpensive consumer-grade
cassette tapes start to lose sound quality after they have been played
even a few times. The most expensive cassettes last a few hundred
plays before noticable degradation occurs, providing the deck they are
played in is in proper working order. These are problems that
significantly affect a theatrical performance, where shows are often
run nightly for weeks on end. This makes tape an undesirable medium
for the playback of sound effects or music for a production.
In addition to the lack of robustness of tape, it is not
a medium that affords easy cueing. Accurate cueing
(positioning the tape so that playback starts at the desired point) is
something of an art, and is yet another unreliable aspect of cassette
tapes. This makes tape difficult to use to play back sound effects
accurately and on cue.
This does not, however, mean that tape is completely useless in a
theatre setting. Multi-track tape decks are available that allow
sound to be recorded in layers. This allows a convenient way to
create complex sound effects when a computer is not available.
Portable cassette decks with recording capability exist, thus they
become prime candidates when recording sound effects at a remote
location. Also, when working on a production that has music being
composed for it, it may recorded ahead of time and presented to the
audio engineer on a cassette. Cassettes tend to be the lowest
common denominator as a medium that people can record and play back
at their convenience. This offers some advantages, but they must be
weighed carefully against the disadvantages of tape.
It should be noted that a lot of professional theatres still use analog
tape in reel-to-reel format. Reel-to-reel allows reasonably easy
cueing, and is a lot more robust than standard consumer cassette tapes.
Next: Digital Audio Tape (DAT)