If you ever get out into the world and start doing gigs, it's great
if you know a little bit about pro audio, such as running an ipod or
laptop to use backing tracks, or even how to setup a full PA system.
This lesson will look at setting up a basic vocal PA system, which
is a rig you could use at most small to medium sized gigs.
The main components of a PA are:
The speakers – powered or passive
A separate amp to run speakers, if speakers are passive
The mixing desk
The foldback wedges (otherwise known as foldback monitors, wedges, or just monitors!)
Pictured below - front view of a small PA setup
Pictured below - picture of an 18" Subwoofer
Let’s start by setting up the 2 top boxes – that is the 2 x 15”
speakers. Make sure they are setup nice and solidly on their stands,
and make sure they are far enough apart that the band can fit in
between them, and far enough forward that no mic is in front of them
(if a mic IS in front of them you will likely get feedback – not
These 2 top boxes are good for higher pitched instruments like vocals, guitars, keyboards, snare drums, cymbals and toms. You can put lower instruments like bass or bass drum through a 15” box, but they won’t have the low end punch that an 18” sub has. If the top boxes were only 12” or 10” you wont have much luck pulling a good sound from a bass drum or really low instrument.
If the speakers are powered, it means they have an amp inside them that makes the speaker work. Therefore they are heavier than passive speakers. If you have a powered speaker, then you need an unpowered mixing desk to run it. That is, a mixing desk without an amp in it.
If the speakers are passive, it means they don’t have an amp inside them and therefore you need a powered mixing desk. That is, a mixing desk that has an amp in it. These mixing desks are built like a large brick, quite heavy (for a mixing desk), but quite powerful and reliable. The good thing with passive speakers is they are light, and they only need 1 lead plugged into them from the mixing desk. Where as, powered speakers need a lead from the desk, and a power lead.
Pictured below, a digital mixing desk.
This is where you plug all your mic leads into, to mic up your
different instruments. You have analogue and digital mixing desks.
An analogue desk has knobs for all the effects like EQ, reverb,
gating etc. a digital desk will have some knobs for things like gain
level, but the majority of the effects will be added in the console.
Here is a pic of a digital desk..
The first thing to do is set the gain levels for each mic. This is the strength of the signal. You want a strong workable signal. Don’t set the gain too high though, or it will distort and clip, and setting it too low will mean you aren’t picking up much sound at all.
Once you have the gain set, you might want to add effects, like a little EQ on the voice – tops, some reverb on the snare etc. entirely depends on the sound you’re going for and the instruments you’re micing up.
If an instrument has a DI – digital input, it means you can run a lead straight into the desk from that instruments amp, rather than having to stick a mic in front of the amp to pick up the sound.
This is where you have wedges or regular speakers pointing back at you so you can hear yourself over the live band sound in a miced up situation. Remember, that with the top boxes in front of the band, pointing at the audience, and guitar, bass and keyboards all blaring away on stage, in can be hard to hear softer instruments well without foldback, particularly vocals. This is why you use foldback. In terms of wiring up the PA, each PA system is different. Please refer to the DVD for a live of example of it being done.