Open Standards/ChoirWire distributed audio mixing/Main principle

Main principle

A standard mixing console consists of several input channels. After tone adjustment, the sound of every channel is put on cross bars of main L/R and monitor channels with different volumes. After all, there is a master volume for main and monitor channels. Every input wire is routed in parallel to the mixing console. Monitor channels are routed back to the stage or musician. A lot of wires are required if there are more than a douzend musicians.

Fig. 2: Classic sound mixing console

To get rid of the wiring horror it would be nice to put all the information of input and output on one wire which collects the inputs and distributes the outputs from and to everywhere. But the problem doing so is, that there is a very huge amount of data. Having 64 input channels with 2x24bits (main)+ 4x12bits (monitor) and sampling rate of 48ksamples/s means a pay load of 294.912Mbit/s. Might be possible – but difficult and expensive to handle. Data reduction is undesired for professional music equipment.

The solution for low real-time data rate without loss of quality is to transfer the Xbars, not the inputs directly. The input channels are put on the stage, the “knobs” are remote controlled. Additionally, if the inputs are already on stage near the musicians, the transfer of the monitor channels (for example for in-ear monitors) is possible.

Fig. 3: Principle of a “ChoirWire” mixing console