Magnetophon

The Army officer who tracked them down, Jack Mullin, would use these machines as the basis of his own designs, which he demonstrated to the San Francisco chapter of the Institute of Radio Engineers in May 1946, and later at the MGM Studios in Hollywood in October of that year.

Attending the SF demo were Ampex engineers Harold Lindsey and Myron Stolaroff, who were inspired to design their own reel-to-reel recorder based on Mullin's modified Magnetophon.

With Bing Crosby arranging financial support for start-up manufacturing, the Ampex 200A went into production and within three years most major recording studios had purchased one.

[7] Later in 1939, the Fe3O4 oxide was replaced by the Fe2O3 type, which gave a significantly better recording quality, so much that the formula became a worldwide standard until the 1970s when chromium dioxide tapes appeared.

Adding a direct-current bias to the record head gave some improvement, but in 1941, Hans Joachim von Braunmühl and Dr. Walter Weber, both engineers at the German national broadcasting organisation RRG (Reichs-Rundfunk-Gesellschaft), accidentally discovered the technique of high-frequency bias in which the simple addition of a high level (about 10X the maximum audio level) inaudible high-frequency tone resulted in a striking improvement in sound quality by effectively smoothing the magnetization of unused portions of the audio band.

Magnetic media are inherently non-linear, but AC bias was the means whereby the magnetisation of the recording tape was made linearly proportional to the electrical signal which represents the audio component.

This CD not only includes the "Emperor" Concerto, but the two other stereo recordings known to exist: a Brahms serenade and the last movement of Bruckner's 8th Symphony conducted by Herbert von Karajan.

[9] Their intelligence experts knew that the Germans had some new form of recording system but they did not know the full details of its construction and operation until working models of the Magnetophon were discovered during the Allied invasion of Germany during 1944-45.

American audio engineer Jack Mullin acquired two Magnetophon recorders and fifty reels of magnetic tape from a German radio station at Bad Nauheim near Frankfurt in 1945.

[11] In 2004, the AEG K-1 Magnetophon was inducted into the TECnology Hall of Fame, an honor given to "products and innovations that have had an enduring impact on the development of audio technology.