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A disc, made of vinyl plastic, pressed into it was an endless circular groove running from the outer edge into the center, used to carry sound. This disc, legally called a phonorecord, but usually called a record, was played on a machine called a record player or phonograph, by placing a small metal needle onto the record.

The vibration of the needle was translated into electrical signals, carried along wires to loudspeakers and when the electrical signals were translated back into vibrations of the speaker it would then play back as music, singing, sound effects or other noise. The coding of the sound determined how fast the record was to be played by specifying the speed to which the playback was to occur. The 4 common speeds were expressed in rpm or revolutions per minute and were

  • 16 rpm (very rare)
  • 33 rpm (disks at this speed were often referred to as long playing or as lps)
  • 45 rpm (discs at this speed were often referred to as 45s), and
  • 78 rpm (rare)
As it eventually eliminated an earlier form of recording, the wax cylinder, the phonograph record has been almost completely eliminated by the compact disc.

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