Wire recording
Wire recording, also known as magnetic wire recording, was the first magnetic recording technology, an analog type of audio storage. It recorded sound signals on a thin steel wire using varying levels of magnetization.[1][2] 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 in 1903.
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. The principles and electronics involved are nearly identical.
Handling and editing[edit]
To facilitate handling as the user threaded the wire across the recording head and affixed it to the take-up spool, some manufacturers attached a strip of plastic to each end of the wire. This was designed to press-fit snugly into either spool. To prevent the wire from piling up unevenly on the spool as it was recorded, played or rewound, on the majority of machines the head assembly slowly oscillates up and down or back and forth to distribute the wire evenly. On some machines, moving wire guides perform this function. These are similar to mechanisms that distribute line across a fishing reel. After recording or playback, the wire has to be rewound before any further use can be made of the machine. Unlike reel-to-reel tape recorders, the take-up reel on most wire recorders is not removable.
A break in the wire is repaired by tying the ends together and trimming. When such a repair is made to an existing recording, a jump in the sound results during playback, but because of the high speed of the wire the loss of an inch due to tying and trimming is trivial and might pass unnoticed. Unfortunately, if the wire breaks it can easily become tangled, and snarls are extremely difficult to fix. Sometimes the only practical solution is to carefully cut the tangled portion away from the spool—an operation which runs the risk of endlessly enlarging the problem—and discard it. The difficulty of handling the wire itself when necessary is arguably the only serious shortcoming, among several definite advantages, of steel wire as a monophonic recording medium.
Editing is accomplished by cutting and splicing. As the knot of each splice passes through the head during playback, a very brief loss of normal contact is inevitable and the resulting dropouts can make editing musical recordings problematic. Although wire is not as suitable for editing as magnetic tape (a plastic-based material) would prove to be, in the field of radio broadcasting it offered tremendous advantages over trying to edit material recorded on transcription discs, which was usually accomplished by dubbing to a new transcription disc with the aid of multiple turntables and stopwatches. The first regularly scheduled network radio program produced and edited on wire was CBS' Hear It Now with Edward R. Murrow.
