Mixing Consoles
Designations
Inputs
Outputs
Signal processing
Sound Control
Mixer - Heart of the Audio System
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Mixer - Heart of the Sound system
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Sound Board, Audio Console, Mixing desk
Main tool of the operator (Board Operator)
Basic Purpose - Controls
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What is it - Selects audio signals from various sources
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Devices are connected to input channels
Microphones
Output channels of CD players, MD players, DAT players,
computers
How Loud will it be - Controls signal level (volume)
Where is it going - Sends audio to various locations
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Devices are connected to outputs
Power amplifiers
Input channels of MD players, DAT players, Computers
Sound Control
Mixer - Heart of the System
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Mixer Nomenclature (Functional Description)
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8x2 = 8 inputs and 2 outputs
16x4 = 16 inputs and 4 outputs
16x4x2 = 16 inputs, 4 group of sub outs, 2 main outs.
Can be used as:
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16 ins mixed down to 4 sub mixes, mixed down to 2
output channels (recording studio or concert
presentation) utilization
24x6 (Theatre type utilization)
16x4x2x1 – adds a mono output
Also can be referred simply by the number of input
channels ex. 8, 16, 24, 48 etc…
Cue Control
Audio System – Sources, Control, Destinations
Equipment System is the Primary Tool of
Modern Theatre Sound Design:
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Block Diagram - Foreigner Setup
Mixer
MD 1
1-2
MD 2
3-4
1-2
Amp
Upstage
L/R
L/R
Cass
Computer
5-6
Amp
Mono
Cluster
7-8
Input
Channels
3
Group/ Outs
Amp
Radio
Record
Player
Input Buss
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This is the section where audio signals from
microphones and/or playback equipment
enters the mixer
This is the area where impedance matching
and Balanced / Un-balanced lines must be
carefully watched
The input buss typically starts at the rear of
the console with either XLR or ¼” RTS
connectors
Input Buss
Input Buss
Rear view of a Mackie t24
Input Buss
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The front side of the console will differ from
manufacturer to manufacturer but they will
have most of the same components
The input channel will usually be arranged to
follow the virtual signal path
Input Buss
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Pre-amplifier
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Pre-amp, trim, trim pot, gain
Used to bring a microphone level signal up to line
level for easy manipulation within the mixer
Also used to adjust the line level inputs from other
sources
Pad or Attenuator
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A switch which will lower an inputs level by a set
amount
Usually used in an input device is too “hot” or much
too high a level
Close up of Pre-amp section
Input channel #
Pad / low end roll off
Gain adjust
Equalization section
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Onboard equalization control will vary greatly
 Simple “tone” control
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Treble and Base
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A fancier version of treble and base control
5 band EQ
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Boost or attenuate high frequencies (treble) or low frequencies (base)
Only adjusts a preset range of frequencies
Hi – Mid – Lo
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Simply varies the balance between high and low frequencies
Able to boost of attenuate 5 different ranges of frequencies
Parametric EQ
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Able to select which frequency range to control and then boost or cut
it
Equalization section
High freq. control
High-mid with selectable
frequency range
Low-mid with selectable
frequency range
Low frequency control
Auxiliary Sends
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Next in line comes a number of Aux sends
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Typically 4 to 8 individual busses
Some or all will be pre or post fader selectable
 Pre-fader – the signal strength (volume) coming from the
aux send channel will be independent on the position of the
channel fader
 Post-fader – the signal strength coming from the aux send
will be dependent on the position of the channel fader
 Often labeled as PFL (Pre-Fade Listen)
Often used to send signals to other devices
 External effect processor
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Reverb or echo
Monitor amp/speakers for performers
Auxiliary Sends
Note the pre-fade switch
8 individual aux send
channels
Signal Routing
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Each input channel will be assignable to one or more output
channels
Very often one selector button will assign the input to two separate
outputs
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1-2 or 3-4 for example
The Pan Pot (Panoramic Potentiometer) adjusts the level of signal going
to each of the pairs
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This is usually to be avoided for theatrical use
Look for single output selection control if possible
PFL – Pre-fade Listen. Sometimes called “solo”
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Example: With the pan pot centered and 1-2 selected, the entire signal is sent
to outputs 1 and 2 equally. If you turn the pot to the left, more signal will be
sent to output 1 than output 2
Usually available to send the signal to a studio monitor or headphones to
allow operator to listen to channel without having to send it into the
house
Channel Mute – turns the channel off. Useful when using wireless mics
Signal Routing
Pan Pot
Output selection
Mute
Note: PFL not available on this model
Other input controls
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Phantom power
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Phase reverse
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A 48v DC power supply applied to the mic input lines
 Used to power condenser mics (to be discussed later)
Inverts the signal coming to the inputs
 Used if pins 2 and 3 on a mic cable are reversed for
example
Ground lift
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Removes the ground connection at the console from the
input cable
 Used to help eliminate ground-loop noise
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To be discussed during troubleshooting
Output Section
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This is the area where audio signals will
leave the mixer, heading toward
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Effects processors
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EQs, delay units, reverb units, recording devices
Power amplifiers and eventually loudspeakers
Output plugs will typically be
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Balanced XLR line level
Balanced RTS line level
Unbalanced ¼” phone plug line level
Unbalanced RCA plug line level
Output Section
Sub or group outputs
Left, Right and Main outputs
Auxiliary outputs
Output Section
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Sub-group output faders
 Sometimes called groups, subs or submasters
 Act as a master fader control for any inputs assigned to it
 Typically these are cabled to power amplifiers
Main outputs
 Sometimes called Left-Right, Stereo or Mix
 Essentially two additional outputs, where the manufacturer has
taken a guess as to what the end user will use them for
 Sub groups can usually be combined and selectively assigned to
the main output
Master output
 Sometimes called Mono
 The main outputs can be combined together and controlled from
one master fader
Aux-Output Section
Aux out mute switch
Aux out gain control
After fader listen
Group-Output Section
“Flying Faders”
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Automated mixers are becoming more and
more common
Started simply to record levels in recording
studios
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Often had 60 or more inputs levels to write down
and could have many many setups.
Flying faders would remember where the faders
were set and you could restore to any setting with
the push of a button
“Flying Faders”
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Today mixers are capable of remembering
output selections, EQ settings, pan settings
etc.
For live mixing it is REQUIRED to still have
actual faders which an operator can move
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Performers will never do the exact thing every
night
The board operator must be able to easily make
adjustments to levels on the fly
For Next Class
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Read
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P. 82 – 90, Leonard
Processing Devices, Kai’s Sound Handbook