NOS stereo technique

The NOS stereo system describes a special microphone arrangement for recording sound in loudspeaker stereophony.

This miking was around the year 1960 by engineers of the Dutch broadcasting, called Nederlandse Omroep Stichting, developed. That's why the name NOS.

Through a series of practical experiments they found a main stereo microphone system, which results in a fairly uniform distribution of the phantom sound sources on the stereo - speaker basis as Hörereignisrichtung ( Angle of Incidence ), at an effective receiving area of the microphone system of ± 40.5 ° = 81 °. This system was set empirically with two small diaphragm microphones with cardioid polar pattern. There was in this case a total axis angle = ± 45 ° = 90 ° angled outwardly with α, and has a microphone based on a 30 cm.

In the formation of the respective frequency Hörereignisrichtung neutral interchannel level differences Δ L and in the same direction interchannel delay time differences Δ t together act as a loudspeaker signals. This recording technique is called mixed stereophonic stereophonic or equivalent. Thus, at the same time the intensity stereophony and Laufzeitstereofonie is applied. Using this signal differences is denoted by equivalence.

Usually this special microphone system must be assembled by the sound engineer of two single small diaphragm microphones. Large-diaphragm Microphones should not be used because of the unbalanced directional characteristics at different frequencies so.

It seems advisable, even with the two parameters axis angle α for Δ L and base a microphone for Δ t to experiment. A sound recording with a main microphone system is supplemented frequently still by spot microphones.