Basics of a Great PA System

When people hear the term 'PA System' they think of the strange horn shaped speaker systems that they used to see at family outings and fair grounds. Although this is a PA System in its own right, we are going to discuss the type of PA system that is used to recreate the original sound source as closely as possible, the sort used at rock concerts, night clubs and gigs.

The 3 main components of any loudspeaker PA system are as follows - a sound source, some sort of amplification and a loudspeaker system or device.

The sound source could really be anything but in normal circumstances it is usually a microphone or an instrument of some type. The sound source will send an output as a waveform signal that is a direct representation of the original sound source.

Generally the original sound source must be processed in some way shape or form in order to change the level of the original signal to a higher level in order to drive the loudspeakers, if you didn’t you wouldn’t hear a thing. For example the output of a guitar would not be anywhere near high enough to drive a loudspeaker directly. An amplifier will be used to bring the signal up to a useful level.

The loudspeaker is connected to the output terminals of the amplifier and is the device that creates the end result, the sound that you hear. The loudspeakers need to be closely matched to your amp in a couple of ways. The first is the amount of power that the amp will feed to the speakers, it is good practice to have the loudspeaker system slightly more powerful than the amplifier in order to minimize the chance of distortion and damage to the speakers. Another important thing to consider is the impedance, the loudspeaker impedance must be the same as the output impedance of the amplifier. A lower impedance than the amplifiers will cause the amplifier to over-heat, if the impedances are higher then efficiency will be compromised.

A mixer will be used when you need to swap between more than one input. The mixer will sit between the sound sources and the amplifier and is in fact a pre-amplifier in itself, amplifying whatever you put at its inputs. The audio mixer will have multiple inputs and may have a few outputs for different amplifiers. The mixer will allow you to choose which inputs make it to the loudspeakers and at what level.

When setting up your PA system it is very important to match everything to everything else in order to maximize the sound quality you achieve and the maximum output power but also to ensure that you don't damage any of your precious equipment.

Before you buy your PA system check all the bookwork, the literature of the equipment will tell you everything you need to know to match everything together. You should end up with a reliable and great sounding piece of kit and hopefully no smoke.