The document discusses audio mixers and their functions. It begins by defining a mixer as an electronic device that combines and routes multiple audio signals and allows control over their levels. It then describes the main modules of a mixer - input modules to control gain and routing, output modules to mix down signals, and monitoring modules to listen to outputs. The document outlines key functions of a mixer like amplification, gain setting, routing, effects sends, talkback, and metering. It notes that while analog and digital mixers function similarly, digital mixers allow mixing of digital audio and integration with recording software.

1. AUDIO MIXERS
By Meenakshi Singhvi
Deputy Director,
All India Radio, Vadodara

2. Mixer
• A mixer/console
is the heart of the
studio.
• It allows you to
combine variety
of audio signals
and gives the
desired output.
2

3. Functioning of Audio console
• In audio, a mixing console is an electronic device
for combining, routing, and changing the level of
many different audio signals, such as
microphones, instruments, audio players
• A mixer is able to control analog or digital signals,
depending on the type of mixer.
• The modified signals are summed to produce the
combined output signals, which are then
broadcast or recorded.
• Mixing consoles are used in many applications,
including recording studios , broadcasting, public
address systems, television, and film.

4. Three Functions of the Mixing
Console
• Amplify
• Mix
• Route or Direct
4

5. Fader PFL
Routing
Switch
Line/mic Selection
Audio
Sources
Microp
hone
Audio
Workstation
CD
Player
Satellite
Receiver
Input modules
Output modules
Master 1 out
Master 2 out
Audio console block diagram
Monitoring modules

7. Various Modules of console
Input Module
• A console have number of input modules say 8 ,12 or
more depending upon requirement. Input modules
controls gain of input audio signal before mixing.
• Input can be configured as line/mic & also facilitated
with PFL (pre fader listening) and routing switches.
• PFL (pre fader listening) is a facility by which a operator
can listen selected input audio before sending it to
output module.
• It is very important during play back and change over
to listen more then one inputs simultaneously without
mixing them.

8. Various Modules of console
Output module
• A typical console normally have 2 or 4 output
modules depending upon requirement. output
modules also termed as master modules.
• These module mix down all audio signal from
intended input modules. These module also have
gain control faders which controls over all output
level.
• A routing switch on the input faders connects
input module to an output module.

9. Monitoring module
• A monitoring module offers facility to listen or monitor
Various audios on a inbuilt or external speaker.
• It has selector switches to switch between audio signals
such as PFL, Master1,Master2, Auxiliary etc. It also has
exciting features like auto muting and auto Dim.
• Auto mute function mutes all the speakers automatically as
soon as any mic fader switch on, (to avoid whistling sound).
• Auto Dim function dims sound of monitoring speakers, if
we want to listen other audio on the console's in- built
speakers.
Various Modules of console

10. Amplification
The “gain stage” is the first stage in the
console.
• Setting proper gain is critical for clear audio.
• Gain settings too low result in noise
• Gain settings too high result in distortion
10

11. Gain Setting
• If gain is too low,
increase in output
levels will also
increase the level of
the noise, as in the
top illustration.
• Proper gain settings
maximize signal to
noise ratio.
11

12. Gain Setting
• Many recording and live
sound consoles provide
“clip indicators” to assist
in proper gain-setting
• When the “peak”
indicator illuminates,
distortion will result.
12

13. Clipping
• Setting gain too high
may result in “clipping.”
• The signal’s wave form
becomes clipped when
it exceeds the circuit’s
capacity.
• Clipping causes the
wave to become
“square” and distorted.
13

14. Audio Metering
• Mixing is aided by meters, Visual monitoring
enables the operator to keep output levels within
these limits.

15. Importance of Audio
level monitoring
• An announcer should monitor and adjust the output
signal level. Needle on meter should cross the 0
mark intermittently during recording or playback.
Needle continuously below 0 indicates low audio
level while needle above 0 mark shows high level.
• Audio level can be adjusted through console input
faders. Normally 0 position on fader pre calibrated
with 0 level on VU meter but needs adjustment
according to input signal level.

16. Routing or Directing
• Sending the signal to a variety of destinations.
16
Typical console outputs
• Monitor or foldback send to headphones
• Effects sends to outboard effects devices
• Auxiliary sends
• PFL

17. Routing or Directing
The pan control routes the signal to the left
and right stereo channels. Center position of
knob will equally distribute the signal to left
and right channels. 17

18. Talkback
A talkback circuit enables a sound engineer or
producer, in the Announcer booth to talk to
artistes and technicians, in the artist booth.
When all studio mics are faded out, the
talkback (TB) may be relayed to the studio
through a loudspeaker. However, when a
studio mic is faded up the feed of TB to the
studio loudspeaker must be cut. This is to
prevent the TB being picked up by the 'live'
microphone and recorded or transmitted.
When mics are 'live', studio personnel must
wear headphones, to hear talkback from the
control room.

19. Mixers
Analog Mixer
Digital Mixer
Digital Mixers, essentially function in the same way as analog
mixers. Digital Mixers accept signals in both analog and
digital form. Converters built into the mixing board manage
these audio signals. All signals are mixed in digital form, when
using a digital mixing board.
The difference in a digital mixer is the ability to mix digital
audio. Audio in this form is much more versatile. This flexible
format allows you to connect to your D.A.W. and synchronize
it with music software programs.

20. Mixers
Advantages of digital mixers.
There is no added noise, distortion, or other signal
degradation as the signal is in the digital domain.
The setup of the console can be saved and loaded
at will.
There are typically many on-board effects and
virtual signal processors available, eliminating the
need for additional hardware modules, and the
associated cost, size, weight, cabling, signal quality
issues, etc.
Disadvantages
 The vast number of channel possibilities is usually
hidden in store, which requires good and quick
memory of the operator when attempting to control
a specific hidden channel.

21. Mixers
Frequency Equalizer Section Frequency
Equalizer controls affects the equalization of the
signal by separately attenuating or boosting a range
of frequencies, like bass, midrange, and treble.
Mute/Solo Button The mute button silences the
audio on a channel so you can hear other stuff in
the mix. A solo button silences everything except
the signal on a channel so you can hear the channel
in isolation.

22. Mixers
PFL
Means Pre-Fade Listen, When you press the
PFL button, the main monitor output will stop
monitoring anything else and the only audio will
be the selected PFL channel(s). This does not
affect the main output mix. PFL is useful when
setting the initial input gain of a channel, as it
reflects the pre-fade level.
Phantom Switch
A capacitor microphone requires a d.c. voltage.
Modern mixing consoles contain d.c. power
supply units that can supply any number of

23. Thank You