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. Image File history File links Size of this preview: 663 × 599 pixelsFull resolution (2300 × 2079 pixel, file size: 1. ... Image File history File links Size of this preview: 663 × 599 pixelsFull resolution (2300 × 2079 pixel, file size: 1. ... Image File history File links Size of this preview: 371 × 599 pixelsFull resolution (1641 × 2648 pixel, file size: 1. ... Image File history File links Size of this preview: 371 × 599 pixelsFull resolution (1641 × 2648 pixel, file size: 1. ... Audio storage refers to techniques and formats used to store audio with the goal to reproduce the audio later using audio signal processing to something that resembles the original. ... This article or section does not adequately cite its references or sources. ...

History

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. Valdemar Poulsen (1869 - 1942) was a Danish engineer. ...

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. This article or section does not cite any references or sources. ... This does not cite any references or sources. ... State Street Village, S.R. Crown Hall, Armour Main Building Illinois Institute of Technology (IIT) is a private Ph. ...

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.

Magnetic Format

Poulsen's original telegraphone and indeed all very early recorders placed the two poles of the record/replay head on opposite sides of the wire. The wire was thus magnetised transversely to the direction of travel. This method of magnetisation was quickly found to have the limitation that as the wire twisted, there were times when the magnetisation 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 sytem was not entirely immune from twisting but the effects were far less marked.

The longitudinal method survived into magnetic tape recording to this day.

Media capacity and speed

Compared to later tape recorders, wire recording devices had a high media speed, made necessary because of the use of the solid metal medium. 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 as 15 or 30 minutes. After recording or playback, the reel had to be rewound, because, unlike the later tape recorders, the takeup reel on most wire recorders was not removable. In practice, the fine wire easily became tangled and snarls were extremely difficult to fix. 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.

Fidelity

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. For the financial services company, see Fidelity Investments. ...

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, being somewhat more resilient than magnetic tape, 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. In aircraft, the flight data recorder (FDR) and the cockpit voice recorder (CVR) are used to record aircraft and pilot behavior in order to analyze accidents, and are usually called black boxes by the news media. ... An example of a FDR (Flight Data Recorder). ...

External links

• Description and photos of a wire recorder and recording media