Tape Recording 75926.8.2 Analogue Multitrack Tape Machines
As mentioned earlier, analogue multitrack machines betray their quality roughly in
proportion to the width of the tape utilized for a given number of tracks. A 2-inch tape,
24 track, which utilizes a 2-inch width tape drawn across 24 parallel heads, is therefore
better than a 1-inch, 24 track, but not necessarily better than a ½-inch, two track! Not
only does a greater head-to-tape contact guarantee a higher tape signal-to-noise ratio (i.e.,
more domains are usefully magnetized) but it also secures less tape dropout. Dropout
is an effect where the contact between tape and head is broken microscopically for a
small period during which the signal level falls drastically. Sometimes dropout is due
to irregularities in the tape or to the ingress of a tiny particle of dust; whichever, the
more tape passing by an individual recording or replay head, the better chance there is
of dropouts occurring infrequently. Analogue tape machines are gradually becoming
obsolete in multitrack sound recording; however, the huge installed base of these
machines means they will be a part of sound recording for many years to come.
26.8.3 Cassette-Based Multitracks
Figure 26.9 illustrates a typical analogue cassette-based portable multitrack recorder
and mixer combined. This type of low-end “ recording studio in a box ” is often termed a
Portastudio and these units are widespread as personal recording “ notebooks. ” Typically
four tracks are available and are recorded across the entire width of the cassette tape
(which is intended to be recorded in one direction only). The cassette tape usually runs at
twice normal speed, 3.75 ips. Individual products vary but the mixer of the unit illustrated
in Figure 26.9 allows for two (unbalanced) microphone inputs and a further four inputs
at line level, of which only two are routed to the tape tracks. Each of the fi rst four inputs
may be switched between INPUT, OFF, and TAPE (return). Selecting INPUT will (when
Figure 26.9 : Cassette-based “ notebook ” multitrack.