A mixer/console may look very complicated but with the right knowledge they are actually a lot simpler than they appear to be. This article is designed to be a generic overview of what all the dials, faders and sections are for on a mixer.
A basic analog mixer can be split up into 3 main sections; Channels Strips, Sub-Mix/Fx/AUX sends and Master. Sometimes there are one or two more sections but for a basic overview we won't need to worry about those extra sections.
In Figure 1, each section has a coloured box drawn around it to show the separation of each of the three sections. The Orange Box groups the Channel Strips section. The Brown Box Groups the Master section and the Purple Box groups the Sub-Mix/FX/AUX section. The extra Tan Box surrounds a single channel in the Channel Strips section.
Channel Strips Section
The Channel Strips section manages all the Input and Routing chains for each channel.
Every input on the mixer is given its own channel on the mixer. Each channel is given an individual number. Numbering on the channels starts from number 1; on the far left and each consecutive channel on the right is given a number that is one more than the one on the its left. There is one exception to the above rule and that is stereo channels. Stereo Channels are usually given two numbers; for example 19/20. The reason for the two numbers on the stereo channels is that they actually take up; in theory, two mono channels (one for sound left and the other for sound right) and thus have two numbers to describe this relationship.
The Channels within the Channel Strips Section
All channels on a mixer have individual settings that run along what is called a Channel Strip. All the dials and faders that belong to a single channel are normally separated from others by a set of printed vertical white lines.
At the top of each channel strip there is a setting called the Gain. The Gain controls how much amplification the channel's Pre-amp does. The Pre-amp is designed to amplify the audio signal so that the audio is at a level the mixer can handle.
Underneath the Gain there may be a little button labelled Low Cut and this setting is used to remove all the low frequencies. The Low Cut is normally set to the 'on' position to remove unnecessary low frequencies. As a general practice this setting may be set to the 'off' position if the channel is handling audio coming from instruments like drums or base guitar or another device that has a lot of low frequencies.
Underneath the Low Cut button you should find the EQ (Equaliser) section. This section is used to boost and reduce high, mid and low frequencies. Normally in this section you will find 3 dials labelled High, Mid and Low and they will boost or reduce the part of the audio they are labelled after. You may also find a secondary set of dials underneath each of the High, Mid and Low dials labelled Frequency. The Frequency dials allow you to modify the specific frequency the High, Mid and Low dials target to boost or cut.
After the EQ section there is a section that allows you to send the audio; being handled that channel, to the Sub-Mix/Fx/AUX section. Each of these types of sends can normally be set to either post of pre fader mode. When in pre fader mode the send dial operates independently of what the channel's fader is set to. This allows you to set the volume level and keep the same volume level going to the send regardless of the channels faders setting. In post fader mode the send dial sends audio at a volume that is at a level relative to the channel's fader. Depending on what the send is being used for the pre or post fader mode may be changed. On some cheaper mixers the sends may be locked into pre or post fader mode.
After the sends section there is a section in the channel strip that has a mute button, Solo/PFL button as well as signal and peak LED's. The mute button allows you to mute the channel so that there is no sound going to the master section. Note that when you mute a channel the sends will still have audio being sent to them; as the mute button does not mute the sends. The Solo/PFL button will allow you to monitor the audio in a channel. Pressing Solo/PFL buttons across multiple channel strips will allow you to monitor multiple channels at once.
The signal LED is normally a green LED and flashes when there is an audio signal going through the channel. The peak LED is normally a red LED and it will flash when the volume of audio in the channel is above what the channel is capable of handling.
At the bottom of the Channel Strip is the channel's fader. The fader controls how much of the amplified audio from the channel is sent to the master section. Zero is in the middle and if the fader is set to this position the volume of the audio being sent to the master is no louder or softer than that of the preamp. When the fader is moved lower than zero the volume being sent to the master section is reduced. When the fader is moved above the zero mark, the audio being sent to the master section is slightly boosted. Note that the negative infinity mark is the fader's off position.
Sub-Mix/Fx/AUX Section
The next section on the right hand side of the Channel Strips section are normally the Sub-mix/Fx/AUX send controls. This section has dials or faders that control the overall volume of Sub-mix/Fx/AUX send. We will look more into the Sub-mix/Fx/AUX sends section in a later article.
Master Section
The Master section is normally the first section on the right of a mixer. This section controls the volume of audio that is being sent to powered speakers or unpowered speaker's amplifier. Some more expensive mixers may also have a dedicated mono fader in the Master section that controls the volume of audio being sent to a sub-woofer.
In this same section there may also be two set of LED's; that line up vertically, that are used in what is called a Level Meter. The Level Meter is used for visually showing the modulation of the audio signal going through the Master section. The Level Meter can also be configured to show the modulation of audio signal being sent to the Solo/PFL.
Glossary:
Routing Chains: Routing Chains is a descriptive term for how audio is electronically connected to other parts of the mixer or other equipment.
Frequency: The frequency of sound is a measurement of how audio sounds in relation to how high or low pitched the sound being produce is.
Zach Radloff lives on the Gold Coast and is studying IT and Multimedia at university and is also a qualified Live Production, Theatre and Events Technician.
Zach Radloff's previous articles may be viewed at www.pressserviceinternational.org/zach-radloff.html