NOS stereo technique

The Nederlandse Omroep Stichting (English: Dutch Broadcast Foundation) found a stereo main microphone system by a number of practical attempts in the 1960s.

This system resulted in a quite even distribution of the phantom sources (hearing event direction) on the stereo loudspeaker base, with two small cardioid characteristic microphones, and a recording angle of the microphone system of ±40.5° = 81°.

With this system are frequency-independent level differences effective and time of arrival differences working together in the same direction as interchannel signals (interchannel loudspeaker signals).

This technique leads to a realistic stereo effect and has a reasonable mono-compatibility.

One should not use double diaphragm microphones because of the produced unbalanced directional characteristics and the larger phase responses.