78 rpm speed: Difference between revisions
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By 1925, the [[78 rpm]] was becoming a standard for [[gramophone records]]. The exact speed depended on the frequency of the alternating current electricity supply. For countries with | By 1925, the [[78 rpm]] was becoming a standard for [[gramophone records]]. The exact speed depended on the frequency of the alternating current electricity supply. | ||
For countries with 50 Hz it was 77.9220779 rpm, the speed of a 3000 rpm synchronous motor reduced by 77:2 gearing. | |||
For countries with 60 Hz it was 78.2608696 rpm, the speed of a 3600 rpm synchronous motor reduced by 46:1 gearing. | |||
Latest revision as of 2011-04-01T17:18:49
By 1925, the 78 rpm was becoming a standard for gramophone records. The exact speed depended on the frequency of the alternating current electricity supply.
For countries with 50 Hz it was 77.9220779 rpm, the speed of a 3000 rpm synchronous motor reduced by 77:2 gearing.
For countries with 60 Hz it was 78.2608696 rpm, the speed of a 3600 rpm synchronous motor reduced by 46:1 gearing.