Wire recording

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A Peirce 55-B dictation wire recorder from 1945.

First US patent for a magnetic recorder; Valdemar Poulsen, inventor.

Wire recording is a type of analogue audio storage in which the recording is made onto thin steel or stainless steel wire. The first wire recorder was the Valdemar Poulsen Telegraphone of the late 1890s, and wire recorders for law/office dictation and telephone recording were made almost continuously by various companies (mainly the American Telegraphone Company) through the 1920s and 1930s. They were most famously introduced as consumer technologies after World War II.

Compared to later tape recorders, wire recording devices had a high media speed, made necessary because of the use of the solid metal medium. Wire recording's most widespread use was in the 1940s and early 1950s, following the development of inexpensive designs licensed internationally by the Brush Development Company of Cleveland, Ohio and the Armour Research Foundation of the Armour Institute of Technology (later Illinois Institute of Technology). These two organizations licensed dozens of manufacturers in the U.S., Japan, and Europe. Consumer wire recorders were marketed for home entertainment or as an inexpensive substitute for commercial office dictation recorders. However, the introduction of consumer magnetic tape recorders around 1948 quickly drove wire recorders from the market.

The audio fidelity of wire recording made on one of these post-1945 machines was comparable to a 78-rpm record or one of the early tape recorders. The Magnecord Corp. of Chicago briefly manufactured a high fidelity wire recorder intended for studio use, but soon abandoned the system to concentrate on tape recorders. Some wire recorders were also used in aircraft cockpit voice recorders and flight data recorders beginning in the early 1940s, mainly for recording radio conversations between crewmen or with ground stations. In this capacity, wire recorders survived somewhat later, being manufactured for this purpose through the 1950s and remaining in use somewhat later than that. There were also wire recorders made to record data in satellites and other unmanned spacecraft of the 1950s to perhaps the 1970s.

The wire reels were recorded or listened at nominally 24 inches per second (610 mm/s), making a typical one-hour reel 7,200 feet (approx. 2195 m) long. This enormous length was possible on a spool of under 3 inches in diameter because the wire was nearly as fine as hair. Since the wire was pulled past the head by the take up spool, the wire speed increased as the diameter of the spool increased. Wires also came in different lengths, such . Editing could be accomplished by cutting the wire and tying the ends together, with the knot sometimes welded with the tip of a lit cigarette. The wire would run through a very small recording head slit on a bobbing head that ensured the wire was placed on the take-up reel evenly.

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• Audio restoration and transfer