"Live" Sound 101
Stage Sound Basics
by David Knight
So you're gigging now, everything is starting to
fall into place. But there's trouble in paradise; your live
sound doesn't sound so great! What do you do, what do you
Well, if you have six thousand dollars and a seasoned sound
guy, this would be the end of the article, wouldn't it? Yeah,
I don't have that stuff either, so I'm going to dive into the
basics of running your own "live" sound system. This will not
be about owning or buying the hottest or most expensive gear
on the market, just the basics. Maybe you have no
experience-this will get you started. Maybe you have a little
bit of time at the mixer, this might be able to clear up a
few things for you.
Let's assume you're tired of renting your sound from that guy
with the big stale garage on the edge of town. The equipment
is older than you and smells like your uncle's jogging shoes.
Let's also assume that you have or are in the process of
acquiring the components to build your own P.A. You won't
need a ton of stuff, here's a list of the basics.
Inputs? You need to know how many inputs are
required. Are you going to mic just the vocals, or have an
input for every guitar, keyboard, drum, horn and vocal? For
the latter, you'll probably want to attempt this after you
get a few dozen gigs under your belt. Let's go with vocals,
kick and snare drum and maybe a keyboard. This will take,
let's say, six to eight inputs. The all-in-one mixer head
available today is quite good. Some have as much as 600 watts
of power (300 per channel, see next paragraph) and built in
DSP-Digital Sound Processors. Cool effects! If you get hold
of one of the older ones, they work great too, however they
may not have enough power nor any effects. If you choose a
rack mount mixer you're going to need....
The amp should be matched to the power rating of
your speakers; or vice-versa depending on which you own
first. How much wattage? Stay away from: Peak Power, Bridged
and 2-ohm values. The one you want is RMS or true RMS.
This means Root, Mean, Squared. It is a mathematical value
that includes the load, duty cycle, cycles of the moon, tides
and what you're wearing. Just stick with RMS power and you'll
do fine. These amp figures apply to powered heads as
If you're playing in small clubs, 200 to 300 watts
each, 2-way (12" or 15" and a horn) or 3-way crossovers (with
an additional mid frequency driver). Larger clubs or
outdoors? Use 500 watts each and up. You should only need
sub-woofers if you're going to mic the bass guitar and the
kick drum. 15" for small clubs, 18" for large. Always know
what the ohms rating is for each speaker cabinet.
The very first thing to understand is "signal flow". When
someone sings into a mic, exactly what path does it take to
get to the speakers? Knowing this will help you to (1) set
the proper levels (2) troubleshoot and fix problems (3) buy
the right components, and (4) have a great sounding band.
Here's a nice Multi-Purpose Sound System to check
Mission Control /