Magnetic Tape

Fritz Pfleumer
Magnetic Tape was invented by Fritz Pfleumer in 1928, improving on earlier designs for magnetic wire by Oberlin Smith in 1882. Pfleumer’s innovation was to use a celluloid sheet coated in ferric oxide powder. By charging a magnetic coil or ‘playhead’ with a current and then running tape through the playhead, oscillations in an electrical current could act like a virtual stylus by polarizing the magnetic iron in the powder layer, creating a versatile and re-recordable medium for audio playback. Because the recording process of magnetic tape relied on the strength of the electric current, this process also greatly benefited from earlier inventions like the ribbon mic, and the triode, without which a recording on magnetic tape would simply not have been possible (Daniel, 1999).
The possibilities of magnetic tape for recording and broadcast would not be fully explored commercially in the United States for 20 years after their invention, primarily due to the onset of World War 2. While magnetic tape itself wasn’t restricted to Germany, the Nazi government prohibited companies like AEG from sharing their innovations on Pfluemers original design with the Allies. An interesting anecdote of the times was that because the Allies were unaware of the advances made by company’s like AEG, the various coding and intelligence agency’s responsible for intercepting Nazi communications were baffled by the quality and simultaneity of Hitler’s radio speeches across Germany and the Nazi occupied territories. This was because they had been recorded on magnetic tape and spliced and played back to prevent the allies from discovering Hitler’s true whereabouts. In contrast, most Allied communication was either transcribed or simply not recorded, and when it was, albeit rarely, it was done on plastic phonograph discs which did not allow for playback manipulation or the kind of fidelity that magnetic tape allowed (Schoenherr, 2002).
Daniel, Eric D. Magnetic Recording: The First 100 Years. New York: IEEE Press, 1999.

Schoenherr, Stephen. "The History of Magnetic Recording." Audio Engineering Society. November 5, 2002. Accessed December 3, 2015.