NMSAT :: Networked Music & SoundArt Timeline

1931 __ Blattnerphone
Louis Blattner (1881-1935)
Comment : An essential requirement of a recording system for broadcasting is that it should be possible to playback as soon as possible after making a recording. When broadcasting began the manufacture of gramophone records was a well established industry, but the process involved in making a record took at least twelve hours. It wasn't until 1930 that a tape recording system suitable for broadcast use was available. As early as 1900 the Danish engineer Valdemar Poulsen (1869-1942) was demonstrating his Telegraphone at the Paris Universal Exhibition. This machine magnetically recorded telegraphy transmissions on a steel wire. In 1924 Dr. Kurt Stille (1873-1957), a German engineer, developed a practical office dictating machine which was produced by the Vox Gramophone Company. This, too, recorded onto steel wire but the quality fell far short of broadcast standards. The BBC became aware of this machine and closely followed developments in magnetic recording. Its interest increased with the coming of the Empire Service, where the same programme would be repeated several times for different time zones. Film producer and showman Louis Blattner (1881-1935), a German who lived in England, formed a company to develop and market Stille's inventions. Among the projects that he set his engineers was to produce a machine which he hoped could be used as a source of sound synchronised to film. In September 1930 a machine was installed for trials at Avenue House, then the home of the BBC's Research Department and the results were deemed good enough for speech, but not for music. The BBC negotiated a five-year rental agreement with the British Blattnerphone Company in January 1931 at £500 for the first year, £1000 per year thereafter, plus £250 for each additional machine. In May 1931 the Blattnerphone was moved to Savoy Hill and entered service. In March the following year it was moved again, this time to the newly constructed Broadcasting House where it was installed on the seventh floor. A second machine soon joined it, allowing recordings of any length to be made by switching between the two recorders. These first machines were made in Germany. They recorded onto 6mm wide steel tape which ran at 5ft/sec. A full spool weighing 21lbs contained just over a mile of tape giving a recording time of twenty minutes. The speed of the D.C. motor had to be controlled by watching a stroboscope attached to the capstan and operating a sliding rheostat. The machines soon proved to be mechanically unreliable. In September 1932 a third machine was installed at BH. Again of German manufacture it used 3mm wide tape which came on spools allowing 32 minutes recording time. The drive was by an A.C. motor. With careful adjustment this machine gave better results than its predecessors, but still suffered from uneven tape speed. At the end of 1932 a programme called "Pieces of Tape" was produced in the Blattnerphone room, being a compilation of several tapes recorded that year. However, the mechanics of the editing process were too laborious for regular productions using the technique. (Roger Beckwith, “Old BBC Radio Broadcasting Equipment and Memories”)
French comment : Au cours des années 1920, les amplificateurs électroniques améliorent l’écoute, et l’Allemand Kurt Stille perfectionne la capacité d’enregistrement des télégraphones. Il parvient à réduire la taille des cylindres d’enregistrement : sur un petit tube de 20 centimètres de longueur, il enregistre toute une symphonie. La Société britannique d’images Ludwig Blattner achète les brevets du procédé Stille et met au point un dispositif d’enregistrement magnétique, nommé blattnerphone. Destiné à l’enregistrement de bandes sonores de films, il est en fait utilisé par la radio, alors en plein développement. La radiodiffusion britannique, bbc, est créée en 1931 ; elle utilise un blattnerphone pour la retransmission mondiale de ses émissions, et pour conserver la trace des discours et des événements importants. Le blattnerphone mesure 1,5 mètre de hauteur et de largeur, et plus de 50 centimètres de profondeur. Il pèse près d’une tonne. Les émissions sont enregistrées sur des bandes d’acier qui défilent devant les têtes de lecture à une vitesse de l’ordre de un mètre par seconde. Une demi-heure d’enregistrement nécessite environ un kilomètre et demi de bande. Le blattnerphone sera utilisé jusqu’en 1945. En 1925, Stille et ses collègues construisent un dispositif qui combine un dictaphone et un répondeur téléphonique. Contrairement à la Société at&t, les sociétés européennes de téléphone autorisent la connexion de dispositifs d’enregistrement magnétique à leurs lignes de téléphone. En 1933, une version améliorée de la machine de Stille est mise sur le marché par la Société Lorenz [voir Textophone]. La police nazie, la Gestapo, achète en quantité ces dispositifs pour espionner les conversations téléphoniques et enregistrer les interrogatoires des prisonniers. Tandis que la radio américaine ne diffuse que des émissions en direct, les radios européennes émettent des programmes enregistrés sur support magnétique. (Nicolas Vicente, “Mémoires Magnétiques”)
Urls : http://nicohx1.chez.com/Page/Magnetique.html (last visited ) http://www.btinternet.com/~roger.beckwith/bh/tapes/blattner.htm (last visited )

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