AKARSH SHEKHAR
The Fundamentals
of Live Sound
Getting into live sound? Here are the
fundamentals that you should build upon.
Types of PA Systems
Let’s take a look at some of the basic kinds of systems out there.
• Personal PAs: A PA is built for one or two performers
as a personal PA. It is a single powered speaker with a
modest onboard mixer and maybe an effect or two, or they
can be as sophisticated as mini line-array systems with
advanced processing, subwoofers, and more. Personal
PAs are great for solo performers and coffee shop gigs.
• All-in-one Systems: These rigs are a lot like personal
PAs in their simplicity, only they tend to be higher
in power than personal PAs and can cover a larger
room or area. They’re great for small mobile rigs.
• Standard PAs: Build a standard PA system
seen in small clubs, large arenas.
Signal Flow & Signal Paths
Signal flow is the path that audio follows in a system. Every
source (mics, instruments) has its own unique signal path.
The Mixing Console
Whether analog or digital mixing desk, mixing consoles
will take multiple inputs, combine them, and send the
combined signal somewhere else (or to multiple places).
Channel: The entire path that an input takes to reach
outputs and buses such as the master/mix bus (the
signal that is sent on to the amp and speakers).
Preamplifier: Used for microphone signals and the
level of the incoming signal that will be processed,
routed, and combined elsewhere in the mixer.
Inserts: Put outboard gear directly in line with
your input channels. Sometimes you can switch
the order of the insert to pre- or post-EQ.
EQ: Most mixers have at least a simple EQ in line with
each channel, typically right after the preamp.
Auxiliary (Aux) Sends: In live sound, aux sends
act just like faders, only they split off signal to a
separate bus (mix) and are sent to dedicated outputs.
Also used for outboard processing and effects.
Channel Faders: They’re technically volume
controls followed by buffer amplifiers and are
generally used to reduce volume, not boost it.
Master Fader: Controls the overall volume of your
board, just an output volume knob but on a slider.
Group Faders: Control drum kits, multi-miked guitar cabinets,
groups of similar instruments (strings, brass, vocals), and more.
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Master Section: Controls everything else your
board can do like effects processing, master bus
processing (e.g., adding compression to the whole
mix), setting return volumes for your aux sends.
PA Speakers
The biggest distinction between powered (also called
active) and unpowered (also called passive) speakers
is that powered speakers have their own internal
amplifiers, whereas unpowered ones don’t.
Monitoring
Performers need to be able to
hear themselves onstage;
so monitors come in.
• Stage Monitors: Sit at the front
of the stage and point back
and up at the performers.
• Personal Monitors: Cut
down stage volume and
hear themselves better,
personal monitoring
systems are alternative to
traditional stage monitors.
Feedback and How to Avoid It
Feedback is easy to avoid:
• Get a graphic EQ: the more
bands, the better.
• Hook up your EQ as the last
thing before your speakers.
• With your mics on the stage,
slowly turn up your mixer’s volume
until you hear feedback.
• Find the offensive, ringing
frequency band on your EQ and
cut it until the feedback stops.
• Turn up the volume until it rings
again. Find the next ringing frequency
and cut that. Repeat until you either
run out of frequency bands or require
a lot of gain to instigate feedback. With
no set volume, rely on a bit of trial
and error. Once you have that EQ set,
stick it in a locking equipment rack.
• Or get Feedback Suppressors