MAGNETIC TAPES

DescriptionTapes to record and play back sound
ManufacturerAgfa, Eerspule
Time Period
Components
DetailsOne full set of tape and case (magnetophonband 260 double play tape)
Four empty cases (Agfa magnetband, Eerspule 13)
DimensionsCases: 13.5 x 13.5 cm
Tapes: 13 cm diameter
LocationUCL Cabinet of Obsolete Media
Inventory nºUCL201704

Magnetic tape is a medium that was designed for analogue audio recording, consisting of a length of plastic film that is given a magnetisable coating onto which the recording is made. The base of the tape is often polyester, as this allows it to have the desired level of strength and elasticity, preventing it from snapping or stretching[1]. The magnetisable coating usually consists of a metal oxide, most commonly ferric oxide, but chrome dioxide is also used. These coatings impact the properties of recordings; ferric oxide typically produces a limited high frequency response whereas chrome dioxide has a greater capacity for high frequencies but also has a higher hiss level[2]. When a recording is made using a tape recorder, the acoustic signal is converted into a corresponding pattern of magnetisation on the metal oxide of the tape, preserving the audio signal so that it can be re-played. The recording can be erased from the tape through exposure to a high-frequency alternating magnetic field. The width of the tape can make it suited to different purposes, for instance a narrow tape of 0.15 inches is used for compact cassettes, whereas a 2-inch wide tape is used for multi-track audio and television recording.

Danish engineer Valdemar Poulsen’s Telegraphone, a device designed in 1898 to record the human voice using a magnetic steel wire, can be seen as a precursor to the development of magnetic audiotape[3]. Leading on from this, in 1928 the Austrian Fritz Pfleumer created a device using paper tape coated in magnetic particles, envisioning it being used to record telephone conversations[4]. The electric company AEG purchased Pfleumer’s patent in 1932, and worked with the chemical company I.G. Farben to refine the use of magnetic particles on different types of tape, resulting in the Magnetophon, a reel-to-reel tape recorder which was unveiled at the Berlin Radio Show in 1935. This device was reportedly used by Adolf Hitler to record speeches. The invention of the tape recorder had a considerable impact on radio broadcasting, as it allowed for worldwide rebroadcasting of programs and the splicing of tapes to edit out unwanted sounds. The Compact Audio Cassette was a magnetic tape format released by Philips in 1962, consisting of two spools[5]. From the early 1970s onwards, the cassette tape became one of the most popular formats for prerecorded music before being superseded by the CD.

F.M.B.


[1] Tim McCormick and Francis Rumsey, Sound and Recording: An Introduction (Oxford: Focal Press, 1992), p. 146.

[2] Glyn Alkin, Sound Recording & Reproduction (Oxford: Focal Press, 1981), p. 150.

[3] William Lafferty, ‘The Blattnerphone: An Early Attempt to Introduce Magnetic Recording into the Film Industry’ in Cinema Journal (1983), 4, p.19.

[4]  James Livingston, ‘100 Years of Magnetic Memories’ in Scientific American (1998), 5, p.109.

[5] Willem Andriessen, ‘THE WINNER’; compact cassette. A commercial and technical look back at the greatest success story in the history of AUDIO up to now’ in Journal of Magnetism and Magnetic Materials (1999) 193, pp.11-12.