Mixer Anatomy: 101
If you have never laid eyes on a large format mixing console before you may think that you are looking at a very complicated at sophisticated machine. For the most part you are exactly right, however that’s not to say that the layout of most large format mixing consoles are not user friendly. Once you grasp these few simple concepts you will be able to confidently control any large format mixer.
The Channel Strip
Pictured above is the Behringer SX3242FX. like most mixer manufactures, Behringer uses a nomenclature reflecting the features of their product. SX3242FX can be broken down as 32 channels 4 busses, 2 main outs, and an onboard digital signal processor for effects. This also goes for the SX2442FX from Behringer which has 24 channels, 4 busses and 2 main outputs. A Channel is a path that an audio signal will follow where it can be routed to various destinations, manipulated, and mixed with other channels in the mixer. The channel strip is laid out vertically with a series of components including: an input section at the top, followed by the mic preamp/line level, EQ section, auxiliary section, pan potentiometer, and finally a bussing section including a “Long Throw Fader.” The number of channels a mixer is comprised of determines the number of instruments or microphones that can be mixed using that particular mixer. The vertical channel strips are arranged side by side and numbered one through 32 in the case of the SX3224FX.
The Input Section
In this section you will see an XLR mic input as well as a 1/4” TS input for line level signals. You will also notice a 1/4” TRS jack labeled insert. This is a very handy feature on mixers as it is used to introduce serial based signal processing such as outboard compressors and external EQ devices to the channel strip.
The EQ Section
This section directly follows the preamplifier and is used to trim and boost specific frequencies of the audio signal. In most cases a these are typically comprised of a fixed Hi and Low band in conjunction with a sweepable semi-parametric EQ for the Mid frequencies, meaning you can select the specific frequency to boost or trim. In this section you will often find High and Low cut filters.
The Aux Section
In this section you will find the numbered auxiliary sends which are used to route copies of the channel strips signal. The auxiliaries are used to perform two main functions. The first is to create parallel effects using time based processing i.e. reverbs and delay effects. This is done by sending a copy of a signal to a device that processes an echo like effect. This effect can then be mixed back in the main outs of the mixer or can be brought into another channel strip for further manipulation. This results in the original signal mixed with the effect. The second function of the aux section is to create individual headphone or monitor cue mixes for the artists during performance. Each channel strip has the same auxiliary sends so each instrument can have a specific level copied to them auxiliary resulting in as many different headphone mixes as you have auxiliary sends. This is great for the drummer who needs to hear more bass player and the singer who needs to hear more of his or herself. Both mixes can be accomplished simultaneously using only two aux sends.
At the bottom of the Channel strip you will find the bussing section. Here you can select what if any busses the signal will be routed with. You can think of busses as extra ways of routing signal out of the mixer either to a channel of a recording device or DAW based recording system. Busses are also used to create submixes which are like mixes within the main mix. For example: your first four channels are comprised of a drum set with mics on a kick drum, snare, and two overheads. In the bussing section all four of those channels can be assigned to bus 1 for a mono mix or bus 1 and 2 for a stereo mix of your drums. Now you will have control over all the drums using only 1 or 2 bus faders in the master section.
In the Master Section you will find all of the Global settings for the mixer as well as the external auxiliary sends/returns and bussing faders. In the case of mixers with onboard digital processing you will also find these controls in the master section as well as the monitor levels and a the faders for the main mix. Here you will also find the talk back microphone as well as talk back level which is used to communicate with the artist as well as slate takes to tape meaning to print audible cues right to your recording media so that they may be kept track of in the mixdown phase of production.