A tour of a mixer, and what each of its various parts does…
The mixer is an essential item in live music, and also in many studios. It is also one of the bits of audio gear that seems to intimidate those who are unfamiliar, due to the seemingly endless controls.
However, it’s all far more straightforward than it looks.
Here, we’ll explain what a mixer does, and take a tour of the features of a typical model.
What does a mixer do?
Put simply, a mixer (sometimes known as a mixing desk, mixing console, mixing board, desk or console) takes various audio sources through its multiple input channels, adjust levels and other attributes of the sound, then usually combine them to a lesser number of outputs.
So, at its most simple, this might involve taking the audio from performers in a live situation, tweaking and adding effects, then combining these to a stereo or mono output which can be amplified with a PA system.
In a studio situation, this might involve taking inputs from microphones or other sources in a live room, and directing them towards the inputs of your recording rig (which could be a computer based set-up with scores of inputs). As a result, some recording desks may have as many outputs that can be routed to as they have inputs. These assignable outputs are usually termed buses or group outputs.
Many mixers describe their input-output functionality with a 3-number descriptor. For example, a 24:8:2 mixer would have 24 inputs, 8 output buses, with a stereo (2 channel) master output. If it said 24:2, this would mean it had no bus outputs.
So at its simplest, a mixer allows the user to take lots of audio sources and manipulate them before sending them to output channels.
Pretty simple, eh?
But what do all those controls do?
Below is a simple summary of what the different controls of a mixer do. The map above shows which part we are referring to. This mixer is a simple 20 input to stereo output design.
The channel is the basic ‘unit’ of the mixer. It is also the reason that many are intimidated by the mixer, as the channel controls are repeated many times over the mixer surface (providing the arsenal of complex looking knobs and faders). The mixer above has 20 sets of channel controls, for example. The truth is that if you understand one channel, you basically understand how a mixer works.
Imagine it a bit like a water pipe. Water enters the mixer at the input, and then travels down through the various parts of the channel to the fader, before being sent to the outputs.
The various parts of the channel are described below.
These are where the audio sources are connected. These can be anything from a line-level signal, such as that from a keyboard or piano, to microphones. Usually, you’ll have both a ¼” jack input for line signals, and an XLR connection for microphones.
These days, it’s common to see stereo input channels, too (like the two to the right of the inputs shown in the mixer above, that aren’t in a coloured box).
The insert is a connection that allows a piece of equipment to be plugged in directly after the input, so that it is unaffected be any of the other processes further down the channel. the most common use for an insert is to connect a compressor or gate.
Here, the insert is a stereo jack, which both sends and returns the signal, to and from the connected device. Commonly, an insert has a separate send and return socket, however.
Gain controls the input level of each individual channel. Here you can set this so that individual sound sources do not cause the channel to overload and distort.
EQ allows the user to change the frequency curve of a sound. For instance, if a sound source is very bright, the high frequencies can be turned down. A 3-band EQ will allow you to boost or cut high, mid and low frequencies separately.
The auxiliary sends can be used for various things. Put simply, turning an auxiliary send up will adjust the level of a channel’s signal that is sent to the auxiliary send output.
The desk here is pitched as a live desk, so these are generally used as ‘monitor send’ controls’. That is, you connect the sends to monitor speakers at the front of a stage, so that the band can here what they are playing more clearly.
Aux sends are also used to send channel audio to an effects unit. When used with a common effect like reverb, it allows the engineer to adjust the level of effect of each individual channel, using just one effects unit. When used in this way, the FX unit output would be connected to the aux return inputs on the mixer. If these do not feature, the FX unit would be routed down an input channel or channels.
Short for ‘Panorama’, this controls whereabouts in the stereo field the sound will be heard. So, turning it all the way to the left will send the signal completely to the left output, and the turning it to the right, to the right output. The area between allows the signal to be more accurately placed by vary the level sent to each of these outputs accordingly.
When using a multi-bus mixer, these pan controls are more important. Often, routing to buses involves pressing a button on the individual channel, but these buttons will correspond to 2 outputs (i.e. 1&2, 3&4, 5&6, 7&8). In this case, to route to bus 1, the user would press the 1&2 button, and turn the pan all the way to hard left. To send to bus 2, the pan would be turned to hard right.
These allow the engineer to mute individual channels. In essence, it stops the channel being sent to any outputs. It’s common to see ‘solo’ buttons here too. These mute everything other than the soloed channel, or channels.
These control the level of each channel to be sent to the outputs (bus, or master). These are the main tools for control the ‘mix’ of sounds to go to the PA or recording device.
These control (you guessed it) the level of signal being sent to the main outputs. In the case of a live set-up, this would usually be the overall level being sent to the PA system.
This is where everything ends up- all of the channels, mixed, adjusted and tweaked, ultimately will come out of these connections to be amplified.
On a mixer with buses, you’ll also see both bus faders and bus outputs, too.
The mixer may look scary if you haven’t used one before, but they’re remarkably simple. And, in the right hands, can be the hub of your performance and recording.
For a full ranger of mixers see our online store.
Joe is a contributor for the Dawsons Music blog. Specialising in product reviews and crafting content to help and inspire musicians of all musical backgrounds.