钢丝录音1898

知名用途

1949年10月1日，中华人民共和国开国大典，曾用钢丝带录音机，播放检阅部队的实况录音，中央人民广播电台同步播放。

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. 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.

History

The wire recorder was invented in 1898 by Danish engineer Valdemar Poulsen, who gave his product the trade name Telegraphone. Wire recorders for dictation and telephone recording were made almost continuously by multiple companies (mainly the American Telegraphone Company) through the 1920s and 1930s, but use of this new technology was extremely limited. Dictaphone and Ediphone recorders, which still employed wax cylinders as the recording medium, were the devices normally used for these applications during this period.

The peak of wire recording lasted from approximately 1946 to 1954.

Characteristics

Magnetic format

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 magnetized 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 recorder was improved by placing the two poles on the same side of the wire so that the wire was magnetized along its length or longitudinally. Additionally, the poles were shaped into a V so that the head wrapped around the wire to some extent.

Handling and editing

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.

Notable uses

In 1944–1945, the 3132 Signal Service Company Special of the U.S. Army's top secret Ghost Army used wire recorders to create sonic deception on the Western Front in the Second World War. Multiple battlefield scenarios were recreated using military sounds recorded at Fort Knox, Kentucky. The wire-recorded audio, which was played back through powerful amplifiers and speakers mounted on vehicles, was used to conceal real Allied deployments, locations and operations.

In 1944 at the Middle East Radio Station of Cairo, Egyptian composer Halim El-Dabh used wire recorders as a tool to compose music.

In 1946, David Boder, a professor of psychology at Illinois Institute of Technology in Chicago, traveled to Europe to record long interviews with "displaced persons"—most of them Holocaust survivors.