Disc 78 turns

The discs (whose golden age was 1920-1950) revolving with 78 turns per minute generally had a diameter of 25 cm (approximately 3 minutes of recording) or 30 cm (approximately 5 minutes of recording) and contained a song by face. Sometimes only a face was used. The 78 turns were the substitutes of the cylinder. One distinguishes the disc 78 turns with needle or side engraving and the disc 78 turns with Saphir or vertical engraving. Their manufacture ceased in the Années 1950 and they are sought today by the collectors.

Reading rate

The mention " 78 tours" must be rather included/understood as a generic term more than literally because these discs could be recorded at speeds going from 66 to 103 turns per minute according to the desired duration of recording. It is true that speed 78 turns was most current. It should be added that the real speed of recording was seldom mentioned on the label of the disc. Moreover, but it is a detail, the speed of 78 turns per minutes is only one approximation, because it is the result of a calculation which utilizes the speed of the engine of the gramophone and the frequency of the electric current. The latter being of 50Hz in Europe and 60Hz in America, the number of revolutions of the discs on these two continents is thus not exactly identical except for some hundredths of turn.

Methods of recording

It is necessary to distinguish two techniques from sound recording: up to 1925, the artists sang in a metal horn directly connected to the stylet used for the engraving of the disc. From this date, the 78 turns are recorded by means of a Microphone.

The disc 78 turns had the characteristic to be recorded on line, i.e. without preliminary passage by a phase of recording on Magnétophone before engraving, this last not being invented yet. This irrefutable fact is not without posing problems: so during the recording one of the musicians made a wrong note for example, it was necessary to throw the disc master and in regraver another while the artists started again their piece since the beginning. Engraving on line did not allow either the assembly of the recordings. Moreover, like it there not of band master for these discs, the only way which the technicians of the recording companies have today to transfer a recording from one 78 turns towards a more modern support such as the CD is to use as source one relatively 78 turns commercial in good state and to numerically filter the noises of surface before the final recopy.

Certain discs 78 turns are invaluable testimonys because they contain historical recordings. When those are of unquestionable interest, in particular the large singers of the 20th century, one does not hesitate to mend these 78 turns to record them over CD. One has today powerful computer tools allowing of " nettoyer" and of " rafraîchir" these old recordings.

See too

Internal bonds

phonographic Long-playing record
Disc
Record player

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