A sound mixer takes multiple audio signals and combines them into one or more output signals. It allows adjusting levels, adding effects, creating monitor feeds, and recording mixes. A mixer has input channels that receive audio sources. Each channel has controls for gain, equalization, auxiliary sends, panning, and level. Auxiliary sends route channel audio to other destinations like effects processors. Subgroups let channels be premixed before sending to the master output. The master fader controls the overall stereo output level. Mixers are used in music studios, television, live performances, and field recordings to combine and process multiple audio sources.

1. Assignment : Lesson 3 Joel Amulraj
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2. Introduction
A sound mixer is a device
which takes two or more
audio signals, mixes them
together and provides one
or more output signals.
The diagram on the right
shows a simple mixer with
six inputs and two outputs.
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3.  As well as combining
signals, mixers allow you to
adjust levels, enhance sound
with equalization and effects,
create monitor feeds, record
various mixes, etc.
 Applications : Music studios,
television Studios, live
performances, Field shoots,
etc..,
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4. Mackie Analog console(24*8*2)
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Channel
Inserts
Aux Levels
Eq’s
Channel
Faders
Sub
Groups
Aux
Masters
Monitoring
Section
Master
Faders
Channel 10

5. Inputs
 Common Inputs Connections:
 The first point of each channel's pathway is the input socket, where
the sound source plugs into the mixer.
 It is important to note what type of input sockets are available — the
most common types are XLR, TS, TRS & RCA Cables.
 Input sockets are usually located either on the rear panel of the mixer
or on the top above each channel.
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6. Input types, plugs & sockets
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7. Inputs
 Channels:
 Each input source comes into the mixer through a channel. The
more channels a mixer has, the more sources it can accept.
 On most sound desks, input channels take up most of the space.
All those rows of knobs are channels.
 Exactly what controls each channel depends on the mixer but
most mixers share common features.
 More channels means more flexibility
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8. Channel Strip Controls
 Gain pot (Mic Pre Amp) Sets input level
to obtain optimal gain
 +48 Switch: (Phantom Power) For
Powering Condenser mics.
 Polarity or Phase Reverse Switch. Flips
the Phase 180 degrees
 Pad Switch: Attenuates input signal by a
preset amount ( 10 dB – 20 dB)
 HPF Switch ( Preset High Pass Filter
75hz – 100hz )
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9. Channel Strip Controls
 Equalizer: It is the process of adjusting the balance
between frequency components within an electronic signal.
 These devices strengthen (boost) or weaken (cut) the energy of specific
frequency bands.
 Aux Channels: Auxiliary channels are a way to send a "copy" of the
channel signal somewhere else. To provide separate monitor feeds or to
add effects (Reverb etc).
 Pan:It allows the user to place the sound source in the stereo field,
from extreme left to extreme right
 Solo / Mute / PFL: These switches control how the channel is
monitored. They do not affect the actual output of the channel.
 Channel On / Off: Turns the entire channel on or off.
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10. Equalization
 Why Eq?? A step toward achieving a high quality and clear
sound.
 Most mixers have equalization controls for each channel.
 Channel equalizers use knobs (rather than sliders), and can be
anything from simple tone controls to multiple parametric
controls.
 It is mainly classified into 3 types:
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11. Auxiliary Channels(Aux)
 Aux is an electronic signal-routing output used on multi-channel
sound mixing consoles used in recording and broadcasting settings.
 It allows you to send a secondary feed of an input channel's audio
signal to another destination, independent of the channel's main
output.
 This allows effect to be added to an audio source or channel within the
mixing console
 The signal from the auxiliary send is often routed through outboard
audio processing effects units (e.g., reverb) and then returned to the
mixer using an auxiliary return input jack, thus creating an effects loop.
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12. Examples
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Fig 1 Fig 2
Aux Sends are mono, Aux returns are stereo

13. Pre Fader / Post Fader
 The auxiliary output from each channel can be either pre-fader
or post-fader.
 Pre Fader
 A pre-fader output is independent of the channel fader, i.e. the
auxiliary output stays the same level whatever the fader is set to.
 A pre-fader Aux Send taps the incoming signal from the channel
at a point that is before the channel fader.
 So, when the channel fader is down, the signal is still being sent
to the aux bus.
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14. Post Fader
 A post-fader output is dependent on the fader level. If you turn
the fader down the auxiliary output goes down as well.
 A post fader Aux Send taps the incoming signal from the channel
at a point after the channel fader. Used as "effects sends,"
 Since the channel fader controls the level of signal being sent to
the main mix as well as the level of signal being sent out the Aux
Send, when the channel fades down, the level of the "wet” signal
follows the level of the "dry" signal.
 If the level of the wet signal did not follow the level of the dry
signal, the effect would still be heard after the channel fades out.
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15. Channel Assigning & Panning
 Panning:
 This is a knob which goes from full
left to full right.
 This is where the channel signal
appears on the master mix.
 If the knob is turned fully left, the
channel audio will only come thru
left speaker in the final mix.
 Turn the knob right to place the
channel on the right side of the mix.
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16. Channel Assigning
 The assign buttons determine where the channel signal is sent.
 The most common alternative is to send the channel to a subgroup
first.
 For example, you could send all the drum microphones to their own
dedicated subgroup which is then sent to the main mix.
 This way, you can adjust the overall level of all the drums by adjusting
the subgroup level.
 For stereo applications it is common to use subgroups in pairs to
maintain stereo separation.
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17. Channel faders
 Each channel has it's own fader (slider) to adjust the volume of
the channel's signal before it is sent to the next stage (subgroup
or master mix).
 A slider is a potentiometer, or variable resistor.
 Two ways to adjust a channel's level:
 Make sure the input gain provides a strong signal level to the
channel without clipping and leave it at that level
 use the fader for on going adjustments
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Channel
Level
Input
Gain
Fader
Level

18. Sub Groups
 Subgroups are a way to "pre-mix" a number of channels on a
sound console before sending them to the master output mix.
 For example, if you have six backing vocalists you can set up a
good mix just for them, balancing each voice to get a nice overall
effect.
 If you then send all six channels to one subgroup, you can adjust
all backing vocals with a single subgroup slider while still
maintaining the balance between the individual voices.
 Many Advantages & uses
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19. Example
 In the following diagram, channels 1 and 2 are assigned directly
to the master output bus.
 Channels 3,4,5 and 6 are assigned to subgroup 1, which in turn is
assigned to the master output.
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20. Output
 L/R mix(The Master fader): The main output from most
mixing devices is a stereo output, using two output sockets.
 This button assigns the signal to the master left/right (L/R)
section of the board.
 This is the easiest way to get signal to the outputs without having
to group them to separate busses.
 The level of the output signal is monitored on the mixer's VU
meters. The ideal is for the level to peak at around 0 dB or just
below.
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21. Conclusion
 That’s it fellas !!. Its really a great time in collecting
these information and creating this ppt. Learnt a lot.
There’s much more in it.
 Hope I have done a good presentation and I hope that
it also helped you to learn a few things. Thanks for
your valuable time in going through this.
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22. Joel Amulraj, Chennai, India
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