Mixing Consoles

Designations

Inputs

Outputs

Signal processing

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

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…

Cue Control Audio System – Sources, Control, Destinations

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

Upstage L/R

Cluster

RadioRecordPlayer

MD 1

MD 2

Cass

Computer

MixerAmp

Amp

Amp

1-2

3-4

5-6

7-8

Input Channels

1 - 2

L/R

Mono

3

Group/ Outs

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

Input Buss

Input Buss

Rear view of a Mackie t24

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

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

Close up of Pre-amp section

Input channel #

Pad / low end roll off

Gain adjust

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

Equalization sectionHigh freq. control

High-mid with selectable frequency range

Low-mid with selectable frequency range

Low frequency control

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

Auxiliary Sends

8 individual aux send channels

Note the pre-fade switch

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

Signal Routing

Pan Pot

Output selection

Mute

Note: PFL not available on this model

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

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

Output Section

Sub or group outputs

Auxiliary outputs

Left, Right and Main outputs

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

Aux-Output Section

Aux out gain control

Aux out mute switch

After fader listen

Group-Output Section

“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

“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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