Audio Recording, Wire

The recording of sound using the principle of remnant magnetism (the residual magnetic fields present in some materials after they are exposed to magnetic fields of sufficient strength) was first proposed in 1878 by the American inventor Oberlin Smith. His ideas, later recorded in a patent caveat, are the intellectual starting point for the development of all modern magnetic recording systems.

Wire recorders are characterized by the use of a solid recording medium with a small circular cross section. The wire is moved rapidly past a recording head, which generates a magnetic field in response to an electrical input, normally from a microphone. The magnetic field leaves the wire permanently magnetized. The field on the wire is then played by moving the wire past a reproducing head, which senses the field and produces a recorded signal that is amplified and played back to recreate the original sound.

The primary advantage of the wire-recording medium is its low cost as compared with solid metal tape; machinery used in piano wire manufacture was easily used to produce wire for magnetic recording. Wire has many disadvantages however. In contrast to tape, which always presents the same orientation to the reproducing head, wire can twist in the transport mechanism, leading to variations in reproduction volume.

As a result, wire recorders can record only a single track, in contrast to the multiple track possibilities of tape recorders. Wire also is harder to splice than tape, and it easily becomes snarled if it escapes from the reels on which it is wound. Finally, steel with ideal magnetic characteristics is very stiff and difficult to pull through transport mechanisms. This problem can be dealt with by using coated wire (developed in the early 1940s), although the higher cost reduces wire’s economic advantages.

The primary application of wire recorders is sound recording. Recordings are analog recordings; that is, the magnetic pattern produced on the wire is an analog copy of the original sound. Wire recorders were also occasionally used for the digital recording of telegraph and radio telegraph signals early in the twentieth century.

The first successful magnetic recorder of any kind was a wire recorder constructed by the Danish inventor Valdemar Poulsen in 1898. Poulsen had been attempting to develop a telephone answering machine, and so he named his invention the Telegraphone (roughly meaning ‘‘distant sound recorder).’’ With the assistance of Danish investors led by the entrepreneur Lemvig Fog, Poulsen began to offer commercial machines in 1903. By that time, Poulsen had abandoned magnetic recording for research on radio transmission, and he and his collaborators turned further development of the telegraphone over to the American Telegraphone Company in the U.S.

After delays caused by financial and technical problems, wire recorders were offered in small numbers to the public by American Telegraphone during the 1910s and 1920s. Total sales amounted to fewer than 300 machines due to high prices, poor sound reproduction quality, and worse quality control. American Telegraphone entered bankruptcy proceedings in 1919 and ceased manufacturing in 1928, though the firm was not formally out of business until 1941.

During the late 1920s and 1930s, the primary manufacturer of wire recorders was the Echophone Company in Germany, later sold to Lorenz. The Textophone (later renamed the Dailygraph) was similar in design to the machine produced by the American Telegraphone Company, but incorporated an electronic tube amplifier to improve sound quality.

The quality of the machines was higher than American Telegraphone products, but prices were just as high. As a result, the device was a niche product, selling primarily to wealthy businessmen interested in cutting-edge technology until 1933. With the rise of the Nazi Party to power after that date, Lorenz sold an increasing number of machines to the Gestapo and other state security agencies in Germany for wiretaps and the recording of interrogations. However, by 1939 competition from tape recorders produced by AEG led to the end of wire recorder production in Germany.

Although several organizations in the Soviet Union and firms in the U.S., most notably AT&T through its Bell Telephone Laboratories subsidiary, experimented with magnetic recording during the 1930s, production of wire recorders for consumer use did not take place until World War II in either country.

Thus, at the same time wire recorder production was ending in Germany, it was increasing dramatically in the USSR and the U.S. However the military provided the major market for wire recorders in both countries. The primary application was in situations where vibration rendered other forms of recording impossible. Wire recorders were used primarily by reconnaissance pilots to record their comments while in flight and by journalists reporting from frontline locations.

Most military recorders used cassette designs to eliminate problems with threading the fine wire through a recording head. Cassettes also minimized the chance of wire snarls because of wire coming off the reels. Improved recording heads and the development of coated wire (an outer magnetic layer electroplated on a more flexible nonmagnetic inner core) meant that the sound quality of wartime wire recorders was much better than before. However, the most notable improvement in sound quality resulted from the introduction of alternating current (AC) bias, an electronic noise reduction technique originally developed for tape recorders.

The Armor Research Foundation was the leading wartime developer of wire recorders. Armor patented much of its work and then licensed its patents to dozens of firms in the U.S. and abroad in the late 1940s. These firms produced essentially all the wire recorders aimed at the consumer market in the U. S. and Europe after World War II. Annual production of consumer wire recorders peaked at several million around 1950.

In contrast to the high quality of military recorders built during World War II, postwar consumer wire recorders were largely inexpensive units built as cheaply as possible. In particular, very few of them incorporated cassette mechanisms. As a result, snarls and other malfunctions were a constant problem. Consumers put up with these difficulties since wire recorders sold for considerably less than tape recorders in the immediate postwar period.

Wire recorders vanished from the consumer market by the mid-1950s as the price of tape recorders using coated plastic tape dropped. Although they continued to be used in special applications through the 1960s, wire recorders have essentially disappeared with the development of improved tape materials.