VCA Faders
VCA stands for Voltage-Controlled Amplifier. VCA faders were originally found on hardware mixing desks. They allowed the user to control the volume levels of several mixer channels with only one fader. To assign channel faders to a VCA fader, the respective channels must be physically connected with the VCA fader.
In Cubase, the VCA fader function is based on the same concept. VCA faders are assigned to a group of linked channels, a link group. The VCA faders control the following parameters of the link group: volume, mute, solo, listen, monitor, and record.
When you assign VCA faders, they become part of the link group.
If a VCA fader controls a link group, it cannot control another link group. If you assign a VCA fader to another group, the VCA fader is automatically removed from the former group.
You can create several VCA faders without assigning them to link groups straight away.
From a technical perspective, moving a VCA fader to a different dB level adds or subtracts the new value to or from the original values of the channels in the link group.
Example
A channel in a link group has a level of -6 dB, the VCA fader is at the 0 position. If you move the VCA fader to a level of +3 dB, this value is added to the level of the linked channel. The linked channel now has a level of -3 dB.