Audio Engineering

750 Chapter 26

in the playback head causes a current to fl ow in the head’s coil. This is applied to an
amplifi er to recover the information left on the tape.

In an analogue tape recorder, the pattern stored on the tape is essentially a stored
analogue of the original audio waveform. In a digital recorder the magnetic pattern
recorded on the tape is a coded signal that must be decoded by the ensuing operation of
the playback electronics. However, at a physical level, analogue and digital recordings
using magnetic tape (or discs) are identical.

26.2 Magnetic Theory ...................................................................................................

Figure 26.2 illustrates the path of a magnetic tape through the head assembly of a modern
analogue tape recorder. The recording tape is fed from the supply reel across an initial
erase head by means of the capstan and pinch roller. The purpose of the erase head is
to remove any unwanted previous magnetization on the tape. Next the tape passes the
record head, where the audio signal is imprinted upon it, and the playback head, in

Direction

Signal

Head

Tape

Figure 26.1 : Magnetic tape and the head gap.

Supply spool

Guide roller Guide roller

Erase head

Record head

Playback head

Capstan

Pinch roller

Take-up reel

ta

pe

Figure 26.2 : Tape path.