VCA Master tracks emulate the operation of voltage-controlled amplifier channels on analog consoles, where a VCA channel fader would be used to control, group, or offset the signal levels of other channels on the console.
VCA Master tracks do not pass audio, so they do not have inputs, outputs, inserts or sends. A Mix group is assigned to a VCA Master track, which appears in the VCA track’s Group Assignment selector. The controls of the tracks in that Mix group, called the
slave tracks, are modified by the controls on the VCA Master.