1935: Audio recorder uses low-cost magnetic tape

AEG debuts the Magnetophon commercial audio tape recorder in Berlin

In 1926, American inventor Joseph A. O'Neill of New York, NY patented “a strip of paper or other cheap material on which is deposited a trail or line of magnetic material, such as metal particles, dust or fine shavings” for reproducing sound. He did not pursue it commercially.

Austro-German engineer Fritz Pfleumer (1881 – 1945) coated 16 mm wide paper strips with fine granules of iron powder as a medium for magnetic recording. He received a patent in 1928 for his “sound paper machine” that he licensed to AEG, Berlin. AEG designed a recording machine and worked with BASF, Ludwigshafen to develop a cellulose acetate-based tape to replace the fragile paper. The Magnetophon K1 recorder and Type C tape debuted at the Berlin Radio Show in August 1935. With superior sound quality and significantly lower cost than competing steel-tape designs, the K4 model introduced in 1938 became AEG’s first commercially successful machine. In the late 1930s, polyvinyl chloride (PVC) emerged as the preferred base material for recording tape until replaced in the 1950s by "mylar" (biaxially-oriented polyethylene terephthalate - BoPET) substrates from DuPont and others. Modern tapes have moved on to improved substrate materials such as PEN polyethylene naphthalate (similar to PET) and aramid (aromatic polyamide, a totally different Kevlar-like material).

John T. Mullin, a technician with Army Signal Corps, returned to the U.S. after WWII service in Germany with a Magnetophon K4 machine. Mullin worked with singer Bing Crosby and engineer Harold Lindsay at Ampex Corporation, Redwood City, CA to produce the Model 200 commercial recorder that was introduced in 1948. Other manufacturers, including 3M in the U.S., BASF in Germany, Philips in the Netherlands, and Sony in Japan, followed Ampex into the market for broadcast and consumer machines. Audio recording technology was adapted to video and data storage applications in the 1950s.

  • O’Neill, Joseph A. “Record for reproducing sound tones and action” U.S. Patent 1,653,467 (Filed: Mar 22, 1926 Issued: Dec 20, 1927)
  • Pfleumer, Fritz. “Lautschriftträger” German Patent 500,900 (Filed: Jan 31, 1928 Issued: June 26, 1930)
  • Lindsay, Harold and Myron Stolaroff, “Magnetic Tape Recorder of Broadcast Quality”, Audio Engineering (1948 Oct) pp. 13–15.
  • Stolaroff ,Myron J. “Low-Cost Precision Magnetic Recorder for Professional Use” Audio Engineering (1949 Au), pp. 17, 18, 30.
  • Lindsay, Harold W. “Precision Magnetic Tape Recorder for High Fidelity Professional Use” Electrical Manufacturing (1950 Oct) p. 134.
  • Selsted, Walter T. “Magnetic Tape Apparatus”, U.S. Patent 2987233 (Filed: 1952 Oct 20, Issued: 1961 Jun 06)
  • "Magnetic Tape" Revolution Exhibit Computer History Museum
  • Mullin, Jack. "Discovering Magnetic Tape," Broadcast Engineering, Intertec Publishing, Overland Park, KS (May 1979)
  • Engel, Friedrich K. “The Introduction of the Magnetophon” in Eric D Daniel, C. Denis Mee, Mark H. Clark eds. Magnetic Recording: The First 100 Years, IEEE Press (1999) pp. 47 – 71
  • Gooch, Beverley R. “Building on the Magnetophon” in Eric D Daniel, C. Denis Mee, Mark H. Clark eds. Magnetic Recording: The First 100 Years, IEEE Press (1999) pp. 72 – 90
  • Schoenherr, Steven. "History of Magnetic Recording" presented at IEEE Magnetics Society Seminar, UCSD (Nov. 5, 2002) (Retrieved on 11.5.14 from: http://www.aes.org/aeshc/docs/recording.technology.history/magnetic4.html)
  • Leslie, John and Ross Snyder "History of the Early Days of Ampex Corporation" AES Historical Committee (December 17, 2010)
  • “Dynamic mechanical analysis of barium ferrite magnetic tapes with aramid and poly(ethylene naphthalate) substrates” by Robert D. Berry and Brian L. Weick, J. Appl. Polym. Sci. 2015, 132, 41478 http://onlinelibrary.wiley.com/doi/10.1002/app.41478/abstract
  • “Protecting Your Archival Data With Improved Tape Dimensional Stability,” Oracle white paper, January 2011, http://www.oracle.com/technetwork/articles/systems-hardware-architecture/tape-dimensional-stability-294733.pdf
  • Mullin, John T. "An Afternoon with John T. Mullin" videotape, Audio Engineering Society, New York (1989)

File name: 1935_Tape_v7
Rev: 11.16.15