Tape Recording
Richard Brice26.1 Introduction
Magnetic recording underpins the business of music technology. For all its “ glitz ” and
glamour, the music business, at its most basic, is concerned with one simple function:
the recording of music signals onto tape or on disc for subsequent duplication and
sale. Before the widespread advent of computer hardware, this technology was pretty
well unique to the music industry. Not that this limitation did anything to thwart its
proliferation—the cassette player was the second most commonplace piece of technology
after the light bulb! Nowadays, with the massive expansion in data-recording products,
audio—in the form of digital audio—is just another form of data to be recorded in
formats and distributed via highways originally intended for other media. The long-
term advantage for music recording applications is the reduction in price brought about
by utilizing mass-produced products in high-performance applications that previously
demanded a precision, bespoke technology.
A sound recording is made onto magnetic tape by drawing the tape past a recording
head at a constant speed. The recording head (which is essentially an electromagnet)
is energized by the recording amplifi er of the tape recorder. The electromagnet, which
forms the head itself, has a small gap so that the magnetic fl ux created by the action of
the current in the electromagnet’s coil is concentrated at this gap. The tape is arranged
so that it touches the gap in the record head and effectively “ closes ” the magnetic circuit,
as Figure 26.1 illustrates. Because the tape moves and the energizing signal changes
with time, a “ record ” of the fl ux at any given time is stored on the tape. Replaying a
magnetic tape involves dragging the tape back across a similar (or sometimes identical)
electromagnet called the playback head. The changing fl ux detected at the minute gap
CHAPTER 26