Hans-Joachim von Braunmühl

Hans-Joachim Maria von Braunmühl (born September 13, 1900 in Carlshof near Tarnowitz , † April 19, 1980 in Ebersteinburg ) was a German magnetic tape pioneer.

Life

Hans-Joachim Edler von Braunmühl was born as the eldest of five children of a forester in Carlshof in East Upper Silesia. From 1918 to 1926 he studied physics and art history at the Universities of Breslau and Munich . With his doctoral thesis "About the temperature dependence of the dielectric constant of some gases" he obtained the degree of Dr. phil.

First he worked as an engineer at Siemens & Halske , in 1930 he joined the Reichsrundfunkgesellschaft (RRG); In 1933 he became head of the technical laboratories.

Walter Weber , whom he had brought from Siemens & Halske, was one of his employees . In 1938 Weber had obtained the patent DRP 693 664 for a negative feedback circuit to reduce the interference voltage , which was used in the AEG Magnetophon  K3.

Magnetophones rustled despite DC bias . Wendell L. Carlson and Glenn W. Carpenter had already patented the AC bias in the 1920s , but they did not pursue it any further.

In the summer of 1940 Braunmühl and Weber looked for a bug in the AEG Magnetophon K3. The negative feedback circuit probably tended to oscillate at high frequencies, which was actually undesirable. Surprisingly, however, this resulted in an improvement in quality. They then superimposed the sound signal of the recording head with a very high frequency for high frequency pre-magnetization and thus had real “ HiFi ” for the first time . The signal-to-noise ratio improved from about 37  dB to 55 dB and the distortion factor decreased from 10% to below 5%. Their "method for magnetic sound recording" (DRP 743 411) was patented on July 28, 1940.

When her patent was sold to AEG , Braunmühl took over the patent and contract negotiations.

After the electro-acoustic laboratory of the RRG due to the war, first by costs at Poznan , in late 1944 after Speinshart had been transferred to the Upper Palatinate, who commissioned American military administration in 1946 with the construction of the radio technical central office in Bad Homburg the Broadcasting Technology as a successor to central office of the Reichs-Rundfunk-Gesellschaft.

From 1947 to 1950 he worked as an engineer for British Acoustic Film in London , in 1950 he took over the technical development of Südwestfunk in Baden-Baden , initially in the role of head of the operating group for central tasks (development and measurement) , from 1960 to his Retired in 1967 as technical operations director.

Under his leadership, the so-called MAZ technology was introduced on German television in 1957 .

Works

• with Walter Weber: Introduction to applied acoustics, especially the newer problems of sound measurement, sound transmission and sound recording ; Leipzig, S. Hirzel, 1936
• A new device for periodically repeating sound recordings . In: Acoustic magazine. 1. Vol., No. 1, 1936, pp. 36-39.
• Electric voice and music transmission . In: Acoustic magazine. 1st vol., No. 3, 1936, pp. 145-155.
• with Walter Weber: About the ability of non-linear distortion to interfere . In: Acoustic magazine. 2nd vol., No. 3, 1937, pp. 135-147.
• The current state of sound recording technology and its application in German broadcasting . In: Acoustic magazine. 3rd vol., No. 5, 1938, pp. 250-258.

Web links

• Literature by and about Hans-Joachim von Braunmühl in the catalog of the German National Library
• Friedrich Engel: Walter Weber's Technical Innovation at the Reichs-Rundfunk-Gesellschaft. (PDF; 669kB)
• Heinz Thiele: No coincidence - the development of HF bias. (on theimann.com )

literature

• Heinrich Koesters: Obituary for Hans-Joachim von Braunmühl. Rundffunkechnische Mitteilungen 24 (1980).

Individual evidence

1. ^ The archive, issues 1–4, German Society for Post and Telecommunications History, 2005; P. 58
2. ^ Forum Magnetophon
3. ↑ History of the IRT
4. ^ Vita of Hans-Joachim von Braunmühl on weka.de
5. ↑ Pictures from the tape . In: Der Spiegel . No. 32 , 1958 ( online ).