VCA Groups in Live Mixing: Remote Fader Control

VCA groups provide remote control over multiple channel faders without rerouting audio. Unlike subgroups that create new audio paths, VCAs (Voltage Controlled Amplifiers) adjust assigned channel faders remotely. This distinction affects aux sends, processing options, and workflow.

How VCA Groups Work

VCA masters act as remote controls for assigned channel faders. Moving the VCA master adjusts all assigned channel faders proportionally.

The audio does not physically pass through the VCA. Channels still route directly to their assigned destinations (main bus, subgroups). The VCA simply controls fader levels remotely.

When the VCA master sits at unity, assigned channels operate at their individual fader settings. Moving the VCA up increases all assigned channels; moving it down decreases them.

Digital mixers achieve this control digitally, often calling them DCAs (Digitally Controlled Amplifiers) since no voltage control actually occurs. The function remains identical.

VCA vs Subgroup Differences

Subgroups create audio paths—signal passes through the subgroup bus. VCAs do not create audio paths—signal stays in original routing.

Subgroups can be processed with inserted EQ, compression, or effects. VCAs have no audio to process—they are control mechanisms only.

Aux sends from channels behave differently. Post-fader aux sends from subgrouped channels are not affected by subgroup fader. Post-fader sends from VCA-assigned channels are affected by VCA control.

Both provide group level control, but through different mechanisms with different implications.

Aux Send Behavior

VCA control affects post-fader aux sends from assigned channels. This is a key advantage for certain applications.

When a VCA master lowers, all post-fader sends from its channels lower proportionally. Effect sends track with VCA control as they would with individual fader control.

Subgroup control does not affect channel aux sends. Lowering a subgroup fader does not change effect sends from those channels.

This distinction matters for effects routing. VCA control maintains the dry/wet relationship as groups are adjusted.

Practical VCA Applications

Drum VCA groups all drum channels. A single VCA fader controls overall drum level while preserving individual fader positions and affecting effect sends appropriately.

Vocal VCA combines lead and backing vocals. Reducing all vocals during instrumental breaks becomes a single fader move.

Band VCA might include everything except vocals, allowing vocal-versus-band balance adjustment from one control.

Scene-to-scene control uses VCAs for quick global adjustments. Different songs might start with VCAs at different positions.

Setting Up VCA Groups

Assign channels to VCA groups through the mixer’s configuration system. Digital mixers typically offer 8-16 VCA/DCA groups.

Each channel can belong to one VCA group (on most systems). Some advanced consoles allow channels to belong to multiple VCAs.

VCA masters typically appear in a dedicated section of the console surface or can be assigned to specific fader positions.

Name VCA groups clearly—“Drums,” “Vocals,” “Band”—for quick identification during performance.

VCA Master Positioning

Unity position means no adjustment—channels operate at their individual fader settings.

VCA masters should typically start near unity. If masters are set low while individual faders are high, gain structure may not be optimal.

The VCA provides trim on top of individual fader settings. Individual faders set the base mix; VCA provides group-level adjustment.

Multiple VCA Assignments

On systems allowing multiple VCA assignment, a channel can respond to multiple VCA masters.

A snare channel might belong to both “Drums” VCA and “Backbeat” VCA. Both masters affect that channel.

This flexibility enables sophisticated control schemes for complex productions but adds complexity.

VCAs and Mute Groups

VCA mute can silence all assigned channels simultaneously. This differs from audio mute—VCA mute typically also affects aux sends.

The interaction between VCA mute and channel mute varies between consoles. Verify behavior on the specific mixer.

VCA mute provides convenient group muting without creating dedicated mute groups.

Workflow Advantages

VCAs preserve individual channel settings while providing group control. Individual fader positions remain visible; VCA adds or subtracts from those positions.

Changing the mix within a VCA group does not require touching the VCA master. Adjust individual channels normally; VCA provides overall trim.

VCA control is intuitive once the concept is understood. The master acts exactly like a remote control for multiple faders.

Combining VCAs and Subgroups

VCAs and subgroups can work together. Channels might route through subgroups for processing while VCA provides level control.

A drum subgroup with compression handles dynamics processing. A drum VCA provides quick level adjustment. The subgroup fader stays at unity; VCA moves for level changes.

This combination provides both processing capability (subgroup) and flexible control (VCA).

Troubleshooting VCA Issues

Channel not responding to VCA: Verify VCA assignment for that channel. Check that the VCA master is visible and active.

Unexpected aux send behavior: Remember that VCA control affects post-fader sends. This may be intentional or may need routing adjustment.

Confusing level relationships: VCA adds to or subtracts from individual fader levels. If channels sound wrong, check both individual faders and VCA masters.