TYPES OF MICROGROOVES
A mono-microgroove is formed on the disc—a lacquer blank the first stage in the manufacturing process by a cutter which moves laterally (side-to-side) only. This is shown in Fig 8.13 through 8.16.
The reproducing stylus will move from side-to-side when tracing the modulated groove, as indicated in Fig. 8.14, and it is easy to visualise that this is the only movement required for the reproduction of a single channel of information.
The depth of the groove does not change. It is of course, usual to speak of grooves, although there is only one continuous spiral. On microgroove discs there are 150–300 grooves to the inch.
In stereo recording, an unmodulated groove would be essentially the same as that on a mono disc. It is, ...
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