What Are AUX, Bus and DCA Groups on a Digital Mixer?

An AUX sends selected channel audio to a separate mix, a bus is a general internal signal path, a subgroup combines audio for processing and routing, and a DCA controls the level of assigned channels without combining their audio.

AUX sends

An AUX mix is commonly used for stage monitors, in-ear monitoring, effects sends and broadcast feeds. Each input contributes a different amount, allowing a singer to hear more vocal while a drummer hears more click and bass.

Pre-fader AUX sends remain independent of main-mix fader changes. Post-fader sends follow those changes and are commonly used for effects.

Buses and subgroups

A bus is any shared signal path inside the mixer. Main left/right is a bus; AUX mixes are buses; internal effects and matrices can also use buses. A subgroup specifically combines audio from assigned channels.

For example, all drum microphones can feed a drum subgroup. One compressor can then shape the combined kit and one fader can adjust the drum group sent onward.

DCA groups

A DCA does not combine audio. It controls the levels of assigned channels while those channels keep their original routing and processing. This allows one fader to move all vocals or all drums proportionally.

Because the audio does not pass through the DCA, inserting processing on a DCA is not the same as processing a subgroup.

Matrices and practical planning

A matrix combines one or more buses to create another output, such as a lobby feed, delay speaker, recording mix or press output. It is especially valuable in installed systems with several zones.

When choosing a mixer, ask how many AUX buses, groups, DCAs and matrices exist and whether the same resources are shared. A headline number can hide routing limits.

Frequently asked questions