page_title: Wire recording
section_title: Magnetic format
hierarchical_section_title: Wire recording / Magnetic format
caption_attribution_description: Reichhalter Reporter W102 Drahttongerät
context_page_description: Wire recording or magnetic wire recording was the first magnetic recording technology, an analog type of audio storage in which a magnetic recording is made on a thin 37 gauge steel wire. The first crude magnetic recorder was invented in 1898 by Valdemar Poulsen. The first magnetic recorder to be made commercially available anywhere was the Telegraphone, manufactured by the American Telegraphone Company, Springfield, Massachusetts.
  The wire is pulled rapidly across a recording head which magnetizes each point along the wire in accordance with the intensity and polarity of the electrical audio signal being supplied to the recording head at that instant. By later drawing the wire across the same or a similar head while the head is not being supplied with an electrical signal, the varying magnetic field presented by the passing wire induces a similarly varying electric current in the head, recreating the original signal at a reduced level.
  Magnetic wire recording was replaced by magnetic tape recording by the 1950s, but devices employing one or the other of these media had been more or less simultaneously under development for many years before either came into widespread use.
context_section_description: Poulsen's original telegraphone and other very early recorders placed the two poles of the record/replay head on opposite sides of the wire. The wire is thus magnetised transversely to the direction of travel. This method of magnetization was quickly found to have the limitation that as the wire twisted during playback, there were times when the magnetization of the wire was at right angles to the position of the two poles of the head and the output from the head fell to almost zero.
  The development was to place the two poles on the same side of the wire so that the wire was magnetised along its length or longitudinally. Additionally, the poles were shaped into a "V" so that the head wrapped around the wire to some extent. This increased the magnetising effect and also increased the sensitivity of the head on replay because it collected more of the magnetic flux from the wire. This system was not entirely immune to twisting but the effects were far less marked.
caption: German Reichhalter Reporter W102 wire recorder (c. 1950).
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