Knowing and Understanding Audio Mixing Consoles
Getting to know the mixer
Learning to use an audio mixer might initially seem like a daunting task, with all the buttons, knobs, and faders. But keep in mind that every channel has the same controls. Once you learn how to control one channel, you’ll know how to control every channel.
Every channel on a mixer is either mono or stereo with an XLR, 1/4” or RCA connection. (Some inputs are designed to handle both XLR plugs from microphones as well as 1/4” inputs.)
A channel strip is a group of circuits and controls that function together on a given mixer channel to affect the audio signals that pass through it. These usually include:
- an input jack where an external instrument, microphone etc. connects to the mixer. XLR inputs are balanced to minimize noise and interference. Other inputs accept RCA or quarter-inch TRS connectors. Some accept both XLR and 1/4” plugs
- a microphone preamp that amplifies the relatively weak mic signal, raising it to line-level strength
- equalization, abbreviated as EQ, adjusts the signal’s frequency response in three or more bands
- dynamics processing that may include compression or gating (discussed below)
- routing that directs the signal to other mixer buses and external devices
- a pan control for balancing left and right output
- a fader, which slides along a track to control the input or output level of a channel
- a meter or light display that visually shows the output of each channel
Getting more control from a mixer
If you want to be able to make quick adjustments to your mix during a live performance without throwing things out of balance, look for mixers that offer multiple buses.
Basically, once the levels of each channel are set, the signals are combined into either the main mix or into sub-mixes that can be assigned to buses. Buses can be visualized as circuit intersections where the output from several channels meet. Each mixer channel routes its signals to a specific bus or group of buses. These buses allow you to adjust signals as a group before they go into the final mix and out to the speakers. So, for instance, you can easily make adjustments to all the vocals or all the drums using a single group fader control. Also known as auxiliary sends, auxiliary buses can also be used to route mixes to headphones, external effects processors, monitor speakers, or in-ear monitors.
You can also make additional enhancements using buses. For example, two-bus mixers normally have a pan control to send a signal to the left or right bus, creating a stereo output. There also may be insert points where you can apply effects to buses before the final mix.