After the advent of microphones and electronic amplification, the next technical revolution in sound recording came with the introduction of magnetic tape recorders. The technology of magnetic recording dates back to 1898, when Valdemar Poulsen patented the Telegraphone, a device that recorded the electrical audio signal from a telephone transmitter as variations in magnetic flux on a length of steel piano wire. Over the next thirty years the technique evolved very slowly. By 1930, advances in electronics allowed the first commercially successful wire recorders to be introduced as dictating machines and telephone recorders in Europe and North America. Recording on solid steel media, whether wire or tape, remained the dominant form of magnetic recording outside Germany until about 1950. The Museum has 17 such recorders dating from the 1940s and 1950s. Perhaps most interesting, however, is our Blattnerphone, or Marconi-Stille recorder. This large device, which recorded on steel tape 3 mm wide, was developed in Germany and sold to several radio broadcasters, including to the forerunner of the Canadian Broadcasting Corporation in 1933.

Fig. 24. General Electric 50-A wire recorder (690724), mid 1940s. (Peter Lindell/CSTM)