Audio Recording, Tape

Tape recorders were the dominant technology for sound recording in the second half of the twentieth century. By combining low cost, high fidelity, and flexibility in editing, they came to dominate both consumer and professional recording during this period. In addition to sound, tape recorders were used for video and data recording, which are discussed in separate entries.

Tape recorders are characterized by the use of a recording medium with a flat cross section. The tape 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 tape permanently magnetized. The field on the tape is then played back by moving the tape past a reproducing head, which senses the field and produces a signal that is amplified to recreate the original sound.

Valdemar Poulsen, inventor of the first wire recorder in 1898, also experimented with tape recorders around 1900. His machines used a solid metal tape, which provided superior performance since the recording medium always had the same geometrical relationship to the reproducing head as the recording head (wire could twist about its axis, resulting in variable sound quality). However, solid metal tape was much more expensive than wire, making tape recorders too costly for most applications.

As a result, solid metal tape recorders were built only for highly specialized applications during the 1920s and 1930s. Lorenz in Germany and Marconi in the U.K. built radio broadcast recorders using solid metal tape, and AT&T in the U.S. built telephone announcing systems, but their high cost meant that only a handful of each type of machine entered service.

The key to more widespread use of tape recorders was the development of particle-coated tape by the Austrian inventor Fritz Pfleumer in 1928. By coating paper tape with small magnetic particles, he dramatically reduced the cost of magnetic tape. Coated tape was also physically much more flexible than solid metal tape, and this made the design of transport mechanisms for the tape much simpler.

Pfleumer sold his invention to the German firm AEG, which then partnered with the BASF division of I. G. Farben to develop a tape recorder. AEG developed and manufactured the machine itself, while BASF developed and manufactured the tape. BASF soon replaced paper with plastic as the backing material, further lowering costs. The AEG machine was first marketed as the Magnetophone in 1935. The firm developed a variety of models for civilian, government, and military use over the next ten years.

The Nazi government made extensive use of the Magnetophone for both security and radio broadcast purposes, and the demand for higher quality reproduction drove the development of a number of innovations. The most significant of these were the invention and widespread use of the ring head, which produced more intense and defined magnetic fields on the tape, and AC-bias, an electronic noise reduction technique. AC-bias was the addition of a very high frequency tone to the input signal during recording, which dramatically reduced noise and made tape recording suitable for music as well as voice recording.

The developments at AEG and BASF were copied in the laboratory in the U.S. and the Soviet Union during World War II, but it was not until the general dissemination of knowledge about the Magnetophone after Germany was occupied by Allied forces that there was widespread interest in tape recording.

The Brush Development Company in the U.S., under the technical leadership of Dr. Semi Joseph Begun, produced the first American tape recorder, the Soundmirror, in 1947. Brush was soon followed by a number of other companies, most notably Ampex, which produced a high-quality recorder suitable for radio broadcast use. Using a combination of German technology and American wartime research, these and other firms in the U.S., Europe, and Japan soon offered a variety of products whose performance matched or exceeded competing recording technologies.

By the early 1950s, tape recorders were the dominant method for making professional sound recordings. They had rapidly replaced other forms of recording in the motion picture industry and were increasingly used in radio broadcasting and the music recording industry. The success of tape recording was due not only to lower cost but also to the ease of editing. Unlike phonograph recordings, magnetic tape could easily be cut and pasted together, much like motion picture film, to make a high quality product. Such editing had been possible with sound-on-film systems, but magnetic recordings could be edited immediately rather than waiting for film to be developed.

The popularity of tape recording for professional use increased further in the 1960s with the development and widespread use of multitrack tape recorders. In addition to the basic ability to separate vocal and instrumental tracks, these recorders provided much easier sound editing in the studio and also allowed artists to experiment with new forms of musical expression. Analog multitrack recorders began to be replaced in the mid-1970s by digital multitrack recorders for studio use. By the end of the twentieth century, most professional recording was digital and increasingly recorded on hard disks or other computer-related formats rather than on tape recorders.

The use of tape recorders by consumers lagged behind that of the professional world. Reel-to-reel tape recorders, the primary consumer versions of the 1950s, were relatively inconvenient to use compared with phonograph record players and other consumer electronics and were usually limited to fixed installations in the home. A variety of cassette formats were developed to address this problem, but it was not until the introduction of the Phillips Compact Cassette (so common by the end of the twentieth century that it was simply referred to as ‘‘the cassette’’ as if it were the only one) and the 8-Track Cartridge in the 1960s that cassettes were widely adopted.

The 8-Track was the first successful high fidelity cassette system, and it was installed in many vehicles in the 1960s and 1970s. Because of the greater physical size and complexity, it eventually lost out to the Phillips cassette. The Phillips format was originally intended for voice recording only, but the development of new magnetic particle formulations in the 1970s, along with the introduction of Dolby® noise reduction, improved sound quality of the Phillips cassette to the point that it matched the performance of the 8-Track and the LP phonograph record and so gained consumer acceptance.

At the end of the twentieth century, tape recorders and especially the Phillips cassette were still the dominant form of consumer recording technology, but they were increasingly being supplemented by newer digital recording formats primarily derived from the computer industry.