DASH

DASH stands for Digital Audio Stationery Head. The DASH specifications include
matters such as the size of the tape, the tape speed and the layout of the tracks
on the tape; also the modulation method and error correction strategy, among
other things. The format is based on two tape widths: 1/4” (6.3 mm) and
1/2” (12.55 mm). For each tape width there are two track geometries, Normal
Density and Double Density and there are also three tape speeds, nominally Slow,
Medium and Fast (a further variation is caused by each of the three speeds being
slightly different according to whether 44.1 kHz or 48 kHz sampling is used).
According to the above, there must be twelve combinations all of which conform
to the DASH format. This could make life confusing, but just because a particular
combination of parameters is possible, it doesn't necessarily mean that a machine
will be built to accommodate it.

The original Sony 3324, and recent 24-track machines, use the normal density
geometry on 1/2” tape which allows twenty-four digital audio tracks, two
analog cue tracks, a control track and a timecode track. (The cue tracks are
there so that audio can be made available in other than normal play speed +/-
normal varispeed). The tape speed at 44.1 kHz is 70.01cm/s. The 3324 is totally
two-way compatible with the larger 3348 which can record forty-eight digital
tracks on the same tape. To give an example, you may start a project on a 3324,
of any vintage, and then the producer decides as the tracks fill up that he
or she really needs more elbow room for overdubs. So you hire a 3348, put the
twenty-four track tape on this and record another twenty-four tracks in the
guard bands left by the other machine. Continuing my (hypothetical) example,
when it is decided that the project is costing too much and going nowhere, the
producer is sacked and another one brought in who decides that the extra twenty-four
tracks are unnecessary embellishments and the original tracks, with a little
touching up, are all that are required. Off goes the 3348 back to the hire company,
the tape - now recorded with forty-eight tracks - is placed back on the 3324
and the original twenty-four tracks are successfully sweetened and mixed with
not a murmur from the tracks that are now not wanted. We are now accustomed
to new products and systems which offer new features yet are compatible with
material produced on earlier versions. This must be audio history's only example
of forward as well as reverse compatibility. It shows what thinking ahead can
achieve.