78 rpm

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 60 Hz it was 78.2608696 rpm, the speed of a 3600 rpm synchronous motor reduced by 46:1 gearing. For countries with 50 Hz it was 77.9220779 rpm, the speed of a 3000 rpm synchronous motor reduced by 77:2 gearing.

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• two albums with same audio and same album number, but
  • different label colors and different performer names: Odeon 4109
  • Odeon 5604 different composition names

• one album but A+B different appearance
  • 02480002713227 victor 38666

• two albums with same number but different compositions
  • Victor 37122
    • http://www.tango.info/02480002713616 Se Fué Sin Decir Adiós | Mar De Fondo
    • http://www.tango.info/02480002713364 Intimas | Mar De Fondo