In most small venues, the PA works as a sound reinforcement system, helping to boost the sound of the vocal and solo instruments. In larger venues, it may also be used to amplify all the back line sound including the drum kit and each individual drum.
As a wide range of sounds need to be dealt with, PA speakers must be able to reproduce the full audio spectrum, but the PA’s main job is to lift vocals over the audio level of the back line.
In a very reverberant room, getting a clear vocal sound can be difficult. As you move closer to the back of the room, the more reverberant sound can overwhelm the direct sound which reduces vocal clarity.
To reduce the risk of feedback the main PA speaker cabinets should be positioned in front of the vocal microphones. The speakers should be set up on stands slightly above the audiences head height and angled slightly downwards. This will concentrate all of the sound in the direction of the audience and not towards the back wall or ceiling. If the speakers are aimed away from any close walls it will reduce the effect of room reflections making the sound clearer, even in smaller more troublesome rooms.
Many bands use backing tracks from CD’s or MP3 players. If the main PA speaker cabinets are in front of the band they may have trouble hearing this backing track. This can cause the band to turn the PA speakers inwards or move the microphone forward so they can hear the backing track. If this action is carried out then next thing they will experience is feedback; this is not a problem with the mixer or the speakers, but is due to the sound the speakers produce looping back into the microphone. If the band needs to hear any type of music whilst performing they will need some form of monitoring system.