Mixing Consoles

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Mixing Consoles

• Designations
• Inputs
• Outputs
• Signal processing

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Sound Control Mixer - Heart of the Audio System

• Mixer - Heart of the Sound system
• Sound Board, Audio Console, Mixing desk
• Main tool of the operator (Board Operator)
• Basic Purpose - Controls
• What is it - Selects audio signals from various
  sources
• 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
• Devices are connected to outputs
• Power amplifiers
• Input channels of MD players, DAT players,
  Computers

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Sound Control Mixer - Heart of the System

• Mixer Nomenclature (Functional Description)
• 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
• 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

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Cue Control Audio System Sources, Control,
Destinations

• Equipment System is the Primary Tool of Modern
  Theatre Sound Design
• Block Diagram - Foreigner Setup

1 - 2 L/R Mono 3 Group/ Outs
1-2 3-4 5-6 7-8 Input Channels
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Input Buss

• 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 TRS connectors

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Input Buss
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Input Buss
Rear view of a Mackie t24
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Input Buss

• 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

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Input Buss

• Pre-amplifier
• 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
• 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

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Close up of Pre-amp section
Input channel Pad / low end roll off Gain
adjust
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Equalization section

• Onboard equalization control will vary greatly
• Simple tone control
• Simply varies the balance between high and low
  frequencies
• Treble and Base
• Boost or attenuate high frequencies (treble) or
  low frequencies (base)
• Only adjusts a preset range of frequencies
• Hi Mid Lo
• A fancier version of treble and base control
• 5 band EQ
• Able to boost of attenuate 5 different ranges of
  frequencies
• Parametric EQ
• Able to select which frequency range to control
  and then boost or cut it

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Equalization section
High freq. control High-mid with selectable
frequency range Low-mid with selectable
frequency range Low frequency control
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Auxiliary Sends

• Next in line comes a number of Aux sends
• 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
• Reverb or echo
• Monitor amp/speakers for performers

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Auxiliary Sends
Note the pre-fade switch
8 individual aux send channels
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Signal Routing

• 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
• 1-2 or 3-4 for example
• The Pan Pot (Panoramic Potentiometer) adjusts the
  level of signal going to each of the pairs
• 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
• This is usually to be avoided for theatrical use
• Look for single output selection control if
  possible
• PFL Pre-fade Listen. Sometimes called solo
• 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

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Signal Routing
Pan Pot Output selection Mute
Note PFL not available on this model
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Other input controls

• Phantom power
• A 48v DC power supply applied to the mic input
  lines
• Used to power condenser mics (to be discussed
  later)
• Phase reverse
• Inverts the signal coming to the inputs
• Used if pins 2 and 3 on a mic cable are reversed
  for example
• Ground lift
• Removes the ground connection at the console from
  the input cable
• Used to help eliminate ground-loop noise
• To be discussed during troubleshooting

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Output Section

• This is the area where audio signals will leave
  the mixer, heading toward
• Effects processors
• EQs, delay units, reverb units, recording devices
• Power amplifiers and eventually loudspeakers
• Output plugs will typically be
• Balanced XLR line level
• Balanced TRS line level
• Unbalanced ¼ phone plug line level
• Unbalanced RCA plug line level

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Output Section
Left, Right and Main outputs
Sub or group outputs
Auxiliary outputs
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Output Section

• 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

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Aux-Output Section
Aux out mute switch
Aux out gain control
After fader listen
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Group-Output Section
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Flying Faders

• Automated mixers are becoming more and more
  common
• Started simply to record levels in recording
  studios
• 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

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Flying Faders

• 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
• Performers will never do the exact thing every
  night
• The board operator must be able to easily make
  adjustments to levels on the fly

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