Mix-minus
From Wikipedia, the free encyclopedia
In audio, a mix-minus is a particular setup of a mixing console, such that the output to a certain device contains everything except the input from that device. This prevents echoes or feedback from reverberating or howling and squealing through the broadcast or sound reinforcement system.
A mix-minus signal is sometimes also known as a 'clean feed' or a 'Select Audio Return' (SAR).
The most common example of this is when hooking up a telephone hybrid to a console, at a radio station for example. The person on the telephone hears everything playing, including the DJ, except that the caller does not hear his or her own voice. This is also often used for television reporters and interview subjects speaking to a host from a remote location. Because of the delay that is introduced in most means of transmission (including satellite feeds and digital fiber optic connections), the remote subject's voice has to be removed from his or her earpiece. Otherwise, the subject would hear himself or herself with a slight (but very distracting) delay.
Another common example is in the field of sound reinforcement. Consider a room with sound stations for multiple users, each station containing a microphone and a loudspeaker. Such a room might be used in a government house of parliament. The microphone in station #1 would feed the loudspeakers in every other station except station #1. In other words, station #1 receives a mix of all microphones minus the station #1 microphone. This enables all participants to hear each other clearly but minimizes problems with acoustic feedback.
