PA Basics: Instruments and Musicians
While not all pieces of kit, they are vital sources in the overall PA System and you need to know how they can effect things.
Instruments
In general you'll want to avoid volume being changes directly on any instrument that provides its own power or has some form of volume control. Usually a half-way setting provides a good signal.
Guitars
There are four main types of guitar from a sound perspective:
- Acoustic Guitar without pickup
Simply add a microphone pointed at the hole, either voice or instrument. - Acoustic Guitars with passive (non-powered) pickups
With a 1/4 inch jack in the side for an instrument cable, not often prone to spikes though would still benefit from a DI box. - Acoustic Guitars with powered pickups
These tend to have small equalisers on the top powered by a pill battery and you can find that musicians turn them up a little too high, haven't turned them on or the batteries are partly dead (gradually fading). Also be careful of spikes. - Electric Guitars
Obviously these are electric and have their own volumes, usually they don't have battery problems but can spike a system so must use a DI box.
Keyboards
They often have not just volumes but also speakers. This can cause a number of issues, eg. the musician wanting to turn up the volume on their speakers but not realising this causes the output volume (that going down the cable). You can also find that the speakers cause a problem with the mix.
Often there's quite a bit of confusion about which output to use on the back of a keyboard, the mono (often the left output) is usually all you need unless providing a full stereo setup.
Instruments with Special Microphones
Some instruments have mics inside them, usually these will plug into a DI Box without much of a problem though some are so small that they need external Phantom Power. This might depend on the mixing desk you have.
Musicians
There's nothing you need to particularly worry about with musicians other than their drastically changing the distance from their instrument or voice to the microphone and hence changing the 'sensitivity' which will impact on overall volume.
The main way to deal with this is simply to explain the optimum distance and someone who isn't consistent will -unfortunately- need to be turned down otherwise it'll overpower the mix inappropriately (don't try to actively change a slider as they move or you'll mess up).
