Oberlin Smith published a description of magnetic recording in Electrical World, Sep. 8, 1888, based on his visit to Edison's lab in 1878, using an electromagnet with a string covered with iron filings. He may have built a working model but no device has survived. Above is the "original drawing of Oberlin Smith (1840-1926) published in the Electrcial World of 8.9.1888. The spoken words are transformed by the telephone A into an electrical sound signal and are recorded in the form of magnetization patterns on the sound carrier C, passing through the recording head B. F = battery, E = take up reel, D = supply reel, J = reel brake." (from Heinz Ritter, 1988) Valdemar Poulsen in 1894 discovered the magnetic recording principle while working as a mechanic in the Copenhagen Telegraph Company. In 1898 he patented the telegraphone, the first successful magnetic recording device.
Poulsen Telegraphone, 1898, from EMTEC
Poulsen Telegraphone, 1898, from EMTEC
Valdemar Poulsen in Denmark would succeed in 1898 where Smith had failed. He built and patented the first working magnetic recorder called the Telegraphone with wire wrapped around a drum and a recording/playback head that moved by a screw thread on top. Poulsen had become a telephone engineer at the Copenhagen Telephone Company in 1893 and began to experiment with magnetism to record telephone messages. By 1899 he filed U.S. patent 661,619 for a vertical wire-covered cylinder, and in 1900 demonstrated improved drum and horizontal wire cylinder models at the 1900 Paris Exhibition. While making these improved models, Poulsen and his partner Peder O. Pedersen discovered the application of a direct current to the recording head, called dc bias, improved the sound quality on a steel tape version of the Telegraphone. At the Paris fair, Poulsen recorded the voice of Emperor Franz Joseph, today preserved in the Danish Museum of Science and Technology as the oldest magnetic sound recording in existence. Listen to sound excerpt.. Poulsen stopped his work on magnetic recording and turned to radio after 1902, and only a small number of his machines were made in Denmark and Germany. The American Telegraphone Company acquired the patent rights in 1905 and made dictating machines, selling 50 to the Du Pont Company. However, the signal remained weak without amplification and the wire spools became twisted and were unreliable. The wax cylinder phonographs of the rival Ediphone and Dictaphone companies were cheaper and more reliable. By 1918, the company went into receivership and stopped manufacturing after 1924. [photo of an original Telegraphone courtesy of John Parncutt, from EMTEC, Ludwigshaven, Germany]
Fritz Pfleumer, ca. 1928 from Ritter, 1988
BASF magnetic tape from Ritter, 1988
When Poulsen's patent expired in 1918, Germany led efforts to improved magnetic recording. Curt Stille developed in 1925 the Dailygraph magnetic wire recorder as a dictating machine. Semi Joseph Begun at the C. Lorenz Co. developed a steel tape recorder called the Stahtonbandmaschine. However, wire and steel tape would be replaced in the 1930s by thin plastic tape. Dr. Fritz Pfleumer was granted in 1928 a patent in Germany for the application of magnetic powders to strip of paper or film. [photo of an original Magnetophon below courtesy of John Parncutt, from EMTEC, Ludwigshaven, Germany]
AEG Magnetophon, 1935, from EMTEC
AEG Magnetophon, 1935, from EMTEC
"In 1930 the Allgemeine Elektrizitatsgesellschaft [AEG] in Berlin decided to start the development of a magnetophone machine, based on the Pfleumer principle. 2 years later there was an agreement of collaboration with BASF, Ludwigshafen: AEG developed the system, BASF an appropriate sound carrier. This collaboration did not come by accident. On the contrary, BASF had the knowledge necessary for the development of magnetic tape. Here since 1925, carbonyl iron powder in the finest particles had been produced for induction coils in telephone cables and for mass cores in the high frequency technique. In addition, experience had been gathered in the manufacture of enamel paint by milling and dispersing of dyestuffs with cellulose acetate and solvents. At the same time the development of plastics had started for the production of foils and fibres. Thanks to this rich experience in 1934 BASF was able to ship the first 50,000 meters of magnetic tape. The tape consisted of a foil of cellulose acetate as carrier material, coated with a lacquer of iron oxide as magnetic pigment and cellulose acetate as binder. During the 1935 Radio Fair in Berlin the Magnetophone and the Magnetic Tape were presented to the public." [quotation and diagrams from Ritter, 1988, pp. 10-12 ]
Beecham concert, 1936, from EMTEC
Beecham concert, 1936, from EMTEC
The first public recording using the AEG Magnetophon was Nov. 19, 1936, with the London Philharmonic orchestra conducted by Sir Thomas Beecham at BASF's own concert hall in Ludwigshaven. Listen to sound excerpt. The tape used for this recording was an improved formulation based on (Fe3O4) Ferric Oxide rather than the original Carbonal Iron which was chemically less stable and had a poor dynamic range of under 30db. The Ferric Oxide had a dynamic range of 37db. Note in the center of the photo a single Neumann bottle microphone that demonstrates the importance of condenser microphones in the electrical era of sound recording. BASF recreated the concert in the rebuilt Feierabendhaus to make a complete digital recording. [photo courtesy of John Parncutt, from EMTEC, Ludwigshaven, Germany]
National Museum of Science and Technology in Denmark, has exhibits of the compass needle used by H.C. Orsted in the discovery of electromagnetism in 1820 and the first wire recorder in the world, invented by Valdemar Poulsen in 1898.
