Revolutions in sound recording
Revolutions in sound recording

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Revolutions in sound recording

2.6 Turning the handle

The owners of the original hand-cranked gramophones were instructed that the standard velocity for ‘seven-inch plates’ was about 70 revolutions per minute. The owner was also warned that failure to turn the plate at the correct speed would lead to a lowering of the pitch if turned too slow, or a raising of the pitch if turned too fast. It is doubtful if true reproduction of the recorded sound was ever achieved by the owners of these machines! A better power source was needed and as electric motors were far too costly, a suitably powerful and inexpensive clockwork motor was used. It was designed and built by Eldridge Johnson, a craftsman with a passion for the gramophone who would later form Victor Talking Machines and Victor Records, which would become RCA-Victor. The clockwork motor proved an immediate success, with Christmas 1896 seeing the Berliner Gramophone Company of Washington, DC ahead of all the competition, with the factory being unable to keep up with the demand. By mid-1897 the ‘Improved Gramophone’, with a new Johnson-designed motor and soundbox, was launched. This model was destined to become one of the most familiar icons in the recorded music field for it was immortalised, along with a small black-and-white fox terrier dog called Nipper, in a painting by Francis Barraud, shown in Figure 12. This painting was to become the trademark of the HMV (His Master's Voice) Company in Europe and Victor Records in the USA.

Figure 12: Barraud with his painting of Nipper entitled ‘His Master's Voice’

The recording and playback speed would ultimately be standardised at 78 revolutions per minute (rpm), as explained below in Box 3. Actually this can never be taken for granted, because recording speeds varied from under 70 to over 80 rpm. To cater for these differences a speed controller was fitted to most gramophones.

Disc diameters also varied but 7-inch (18-cm) playing for two minutes, 10-inch (25-cm) playing for three minutes, and eventually 12-inch (30-cm) playing for up to five minutes became standard. Eventually recordings were put on both sides of the disc – known then, as now, as the A and B sides – offering better value and greater convenience to users.

Box 3: Why 78 rpm was chosen

Discs revolving at 100 rpm would have given a better sound through improved bandwidth but would have shortened the playing time of the disc to less than Edison's original two-minute cylinder. 40 rpm could have increased the playing time but would have offered a poor sound quality compared with cylinders. 70 to 80 rpm was a compromise offering a reasonable sound and an acceptable playing time. With the introduction of mains-powered synchronous electric motors a speed of 78 rpm became standard. This is because for these types of motor, the rotational speed is dependent on the mains supply frequency. With 78 rpm, simple reduction gearing could be used between the motor and the turntable that required minimal changes when converted from the European 50 Hz to the North American 60 Hz mains frequency supply or vice versa.

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