Mixing console
 |
BBC Local Radio Mark III radio mixing desk |
In professional
audio, a
mixing console,
mixing desk (Brit.), or
audio mixer, also called a
sound board or
soundboard, is an
electronic device for combining (also called "
mixing"), routing, and changing the level,
tone, and/or dynamics of audio signals. A mixer can mix
analog or
digital signals, depending on the type of mixer. The modified signals (
voltages or
digital samples) are
summed to produce the combined output signals.
Mixing consoles are used in many applications, including
recording studios,
public address systems,
sound reinforcement systems,
broadcasting,
television, and
film post-production. An example of a simple application would be to enable the signals that originated from two separate
microphones (each being used by vocalists
singing a
duet, perhaps) to be heard through one set of
speakers simultaneously. When used for live performances, the signal produced by the mixer will usually be sent directly to an
amplifier, unless that particular mixer is “powered” or it is being connected to
powered speakers.
|
Nambassa - Doug Rogers & Paul Moss - Sound Engineers |
Mixing consoles became much smaller and lighter with the advent of semiconductors, making equipment for outdoor concerts much easier to transport and set up.At a typical concert, desks are set up Front of House for the public performance mix, side stage for the performers foldback mix, and sometimes in a temporary studio for recording the performances. The largest such performance in
New Zealand was held in 1979 at
Nambassa. The
Kiwi 'number 8 wire' mental set ensured a success, up against many obstacles at the time. see image.
 |
Yamaha 2403 audio mixing console in a 'live' mixing application |
The input strip is usually separated into these sections:
* Input Jacks
* Input Section
* EQ Section
* AUX Section
* Fader / BusOn the Yamaha Console to the right, these sections are color coded.
Each signal that is
input into the mixer has its own
channel. Depending on the specific mixer, each channel is
stereo or
monaural. On most mixers, each channel has an
XLR input, and many have
RCA or quarter-inch
Jack plug line inputs.
Below each input, there are usually several rotary controls (knobs, pots). The first is typically a
trim or
gain control. The inputs
buffer the signal from the external device and this controls the amount of amplification or attenuation needed to bring the signal to a nominal level for processing. This stage is where most noise or interference is picked up, due to the high gains involved (around +50
dB, for a microphone). Balanced inputs and connectors, such as XLR or
Tip-Ring-Sleeve (TRS) quarter-inch connectors, reduce interference problems.
There may be
insert points after the buffer/gain stage, which are used to send to and return from external processors which should only affect the signal of that particular channel. Insert points are most commonly used with effects that control a signal's
amplitude, such as
noise gates,
expanders, and
compressors.
The Aux sends are used to send the incoming signal to external devices. Aux sends can either be pre-fade or post-fade, in that the level of a pre-fade send is set by the control, whereas post-fade depend on the position of the channel fader as well. Aux sends can be used to send the signal to an external processor such as a reverb, which can then be routed back through another channel or designated aux returns on the mixer. These will normally be post-fader. Pre-fade aux's are used to provide a monitor mix to musicians onstage, this mix is thus independent of the main mix.
Further channel controls affect the
equalization of the signal by separately attenuating or boosting a range of
frequencies (e.g.,
bass, midrange, and
treble frequencies). Most large mixing consoles (24 channels and larger) usually have sweep equalization in one or more bands of its parametric equalizer on each channel, where the frequency and affected bandwidth of equalization can be selected. Smaller mixing consoles have few or no equalization control.Some mixers have a general equalization control (either graphic or parametric).
Each channel on a mixer has an audio taper pot, or
potentiometer, controlled by a sliding volume control (
fader), that allows adjustment of the level, or amplitude, of that channel in the final
mix. A typical mixing console has many rows of these sliding volume controls. Each control adjusts only its respective channel (or one half of a stereo channel); therefore, it only affects the level of the signal from one microphone or other audio device. The signals are summed to create the main
mix, or combined on a
bus as a submix, a group of channels that are then added to get the final mix (for instance, many drum mics could be grouped into a bus, and then the proportion of drums in the final mix can be controlled with one bus fader).
There may also be
insert points for a certain bus, or even the entire mix.
On the right hand of the console, there are typically one or two master controls that enable adjustment of the console's main mix output level.
Finally, there are usually one or more
VU or
peak meters to indicate the levels for each channel, or for the master outputs, and to indicate whether the console levels are overmodulating or
clipping the signal. Most mixers have at least one additional
output, besides the main mix. These are either individual bus outputs, or
auxiliary outputs, used, for instance, to output a different mix to on-stage
monitors. The operator can vary the mix (or levels of each channel) for each output.
As audio is heard in a logarithmic fashion (both amplitude and frequency), mixing console controls and displays are almost always in
decibels, a logarithmic measurement system. This is also why special audio taper
pots or circuits are needed. Since it is a relative measurement, and not a unit itself (like a percentage), the meters must be referenced to a nominal level. The "professional" nominal level is considered to be +4
dBu. The "consumer grade" level is âˆ'10
dBV.
For convenience, some mixing consoles rack's contain a
patch bay or patch panel. These maybe more useful for those not using a computer with several plugins on their software.
Toshimaru Nakamura is perhaps the first person to use a mixing board as a
musical instrument.
Most, but not all, audio mixers can
* add external
effects.
* use monaural signals to produce stereo sound by adjusting the position of each signal on the
sound stage (
pan and
balance controls).
* provide
phantom power (typically 48
volts) required by some microphones.
* create an audible tone via an
oscillator, usually at 440
Hz, 1 kHz, or 2 kHz
Some mixers can
* add
effects internally.
* interface with computers or other recording equipment (to control the mixer with computer presets, for instance).
* be powered by
batteries.
Increasingly, the mixing process is performed on screen, using computer software. Often, tracks are built up individually or in groups, the whole composition only being playable after that stage in the process.
Pro_Tools is one manufacturer of hardware, such as
MBox, and software that is suitable.
*
ADT-Audio [
1]
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Alesis [
2]
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Alice [
3]
*
Allen & Heath [
4]
*
Amek [
5]
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AMS Neve [
6]
*
API Audio [
7]
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Audient [
8]
*
Behringer [
9]
*
Cadac [
10]
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Calrec [
11]
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Carvin [
12]
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Crest [
13]
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D&R [
14]
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DHD [
15]
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DiGiCo [
16]
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Fairlight [
17]
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Harris Corporation [
18]
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Harrison [
19]
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InnovaSON [
20]
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Inter-M [
21]
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Lawo [
22]
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Mackie [
23]
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Midas [
24]
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Neotek [
25]
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Radio Systems [
26]
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Rane [
27]
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Renegade Labs [
28]
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Samson [
29]
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Shure [
30]
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Solid State Logic (SSL) [
31]
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Soundcraft [
32]
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Stagetec/Salzbrenner [
33] [
34]
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Studer [
35]
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Tapco [
36]
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Tascam [
37]
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Wheatstone [
38]
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Yamaha [
39]
*
DJ mixer*
Electronic mixer*
AMS-Neve Official Website - The Worlds Largest Mixing Console Manufacturer*
Neve Europe Official Website*
Neve Australia Official Website*
School of Audio Engineering - Global Portal*
Music Production School - SAE Institute, Byron Bay - Providing Audio Engineering Courses.*
Uk Sound And Lighting Community*
How band equipment works*
Glossary of mixer terms*
Mixer how-to*
Mixing and Learning to DJ*
ProAudioGuide*
Introduction to Studio & Live Mixers at
Sweetwater.com*
Digidesign company website
