Main microphone

The main microphone , or more precisely the main microphone system, is a microphone arrangement in stereophonic or surround sound that is used to record the sound of an entire larger body of sound , such as an orchestra , while, in contrast, a support microphone only picks up parts of the arrangement, e.g. B. a single group of instruments. The main microphone system records the loudspeaker signals that have the greatest impact on the hearing effect. These different depending on the microphone system Inter Channel - level differences and Interchannel- time differences introduced.

Recordings of extensive sound sources, such as a symphony orchestra with choir and vocal soloists, make high demands in terms of recording technology in terms of generating convincing transparency , good and clear localization (directional resolution) and the spatial illusion to be conveyed. In order to be able to realize such a sound image for the listener, it is often necessary, especially in rooms with poor audibility , to use several main microphones on the recording side or to use several support microphones in addition to the main microphone .

The best-known main microphone arrangements are the ORTF stereo system , the Decca Tree , and the Blumlein arrangement with two 90 ° crossed eight microphones. But also AB transit time stereophony of any kind, different equivalence stereophony and intensity stereophony with coincidence microphones with different axis angles and directional characteristics are common. The generated level differences follow the distance law with 1 / r .

The puristic (audiophile) ideal of "just two microphones " can rarely meet the complex requirements of a sound recording with many instruments. But no matter how many microphones are used: If a natural sound impression arises, then the question of how “life-like” comes about is of secondary importance.

Recordings with only one main microphone system are often referred to as a “ one-point stereo system ”, even if an AB run time arrangement was used.

The respective “invisible” recording areas of the microphone arrangements with two microphones can be calculated.

literature

Michael Dickreiter, Volker Dittel, Wolfgang Hoeg, Martin Wöhr (eds.): Handbuch der Tonstudiotechnik , 8th, revised and expanded edition, 2 volumes, publisher: Walter de Gruyter, Berlin / Boston, 2014, ISBN 978-3-11- 028978-7 or e- ISBN 978-3-11-031650-6