The Magnetophone appeared at a time in the 1930s when other kinds of magnetic recorders were being developed in Britain, the United States, and Japan. Ludwig Blattner had bought the rights to a steel tape device from Kurt Stille in 1929 that became the Blattnerphone. The BBC needed a recorder for its shortwave radio Empire Service that could broadcast the same program at different times throughout the British Empire, and improved the dc motor of the Blattnerphone with a synchronous ac motor and reduced the steel tape width to 3 mm. The BBC would use these improved steel tape recorders from 1932 to 1936. The Marconi Wireless Company also improved the Blattnerphone for sale to radio stations in Canada, Australia, France, Poland, and Egypt. In 1935, the BBC and Marconi and Stille Inventions Ltd. joined to develop an improved Marconi-Stille recorder with a signal-to-noise ration of 45 dB. However, the steel tape was persistent problem. It took two people to mount the 2700-meter reels that weighed 35 kg, and the brittle tape broke so frequently that the Marconi-Stille recorders came with a built-in spot welder. In the United States, Clarence Hickman at Bell Labs developed a steel tape telephone recorder but Bell did not market the machine outside the company. Semi Begun developed the Soundmirror steel tape recorder in early 1939 at the Brush Development Company in Cleveland, Ohio, that would be used by the military. Marvin Camras invented an improved recording head for wire in 1939 at the Armour Research Foundation in Chicago, and added his rediscovery of ac bias in 1940 for the Model 50 commercial wire recorder introduced in 1940. Kenzo Nagai in Japan also rediscovered ac bias in 1938 and patented its application to voice recording. His work would stimulate the Japanese consumer electronics industry after World War II.
