Magnetic sound process

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Under Magnettonverfahren magnetic recording and reproducing method are for movies to understand.

history

Since the 1930s, attempts have been made to replace the optical sound using magnetic sound methods , but the attempts were not permanently successful until 1947-48. At that time a combination was used, the sound is recorded on magnetic tape , an optical sound negative is made from it and the positive is copied from this for the presentation.

Professional method SEPMAG ( sep arated like netic = magnetically separated) function with magnetic film , that is a perforated tape , which is parallel and synchronously played back for picture film. CINERAMA (from 1952) was the first SEPMAG system in the cinema. SEPMAG systems for magnetic tape are available to amateur filmmakers.

The Magnettonverfahren COMMAG ( com bined like netic = combined magnetic) was spread from the 1950s until the 1980s; the magnetic tape is glued directly to the film and played in a projector with a pickup system. The advantage is that you only need one device instead of two, and the synchronization of picture and sound is no longer a problem. CinemaScope was originally COMMAG, as was Todd-AO 70 mm.

Procedure

9.5 mm

This amateur film format, which was introduced in 1921 but has declined in its distribution since the mid-1950s, allows the use of magnetic sound with one or two sound tracks 0.7 mm wide.

16 mm

As an alternative to COMOPT (combined optical sound, i.e. optical sound process), projection copies are sometimes made with a magnetic edge track (2.4 mm wide). With only a small number of copies, this is more economical than the light tone. For this reason, many 16 mm film projectors are equipped with an alternative magnetic sound reproduction. Although the sound quality is slightly better with magnetic sound, this was almost never the reason for a decision in favor of magnetic sound. The Scopitone music films, which were shown in special jukeboxes, are an exception . A small number of the 16 mm projectors are equipped with magnetic sound recordings in order to offer an easy option for dubbing amateur films in this format.

Normal 8

Normal-8 projectors for magnetic sound have been around since the 1950s. However, these were quite expensive and were not widely used, also because of the modest sound quality that could be achieved at the time. Nevertheless, there were also a small number of home cinema films with magnetic sound in Normal-8 available for purchase.

Super 8

The Super 8 format, introduced in 1965, was designed with a 0.8 mm wide main sound track that could be used either for optical sound or magnetic sound (COMMAG). In practice, the magnetic soundtrack has been the predominant technique for home theater sound films. For own recordings there were film cassettes with or without magnetic soundtrack, whereby in practice, not least for cost reasons, the “silent” film cassettes were the most common.

The 0.45 mm wide compensation track, originally only intended for mechanical reasons, can be used with better projectors for duoplay dubbing or stereo sound.

Magoptical

This is a special technique that has rarely been used. It allows the production of bilingual 16 mm film copies, in which the language for projection can be selected simply by switching between magnetic and optical sound. During production, an optical sound copy is subsequently provided with a 1.2 mm wide magnetic sound track that covers exactly half of the optical sound track. In the middle of the film this track has to switch to the other half. This prevents a step from being looped into the magnetic head when playing back frequently. This magnetic sound track is then recorded with the second language version. The disadvantage is a lower dynamic and, due to the necessary higher gain, increased noise.

Magnetic sound films in film archives

Older magnetic sound films are increasingly showing undesirable signs of aging. They are often more or less strongly corrugated, since the glued-on soundtrack obviously shows a different shrinkage behavior than the film itself. This is particularly noticeable when the compensation track has been saved for cost reasons. An old magnetic sound track can also be curved in itself, as a result of which it no longer lies flat on the magnetic sound head. In this case, the playback quality is greatly reduced. Only light-tone copies can therefore be considered long-term archival projection copies.

See also

literature

  • Joachim Polzer (Hrsg.) Weltwunder der Cinematographie - Contributions to a cultural history of film technology (6th edition 2002) - Rise and fall of the sound film - with historical presentations on optical sound and magnetic sound. Polzer Media Group, Potsdam 2002 - ISBN 3-934535-20-8
  • Jerrold E. Kemp: Planning and Producing Audiovisual Materials. Chandler, Scranton, 1963 f.