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How to set up your PA system speakers [basic]

How to set up your PA system speakers [basic]

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In recording engineering, the most important thing to do is position the microphones well. Anything else is secondary to that (as long as your equipment works correctly of course).

This leads to two simple but important 'golden' rules…

The golden rules of microphone positioning

  • Point the microphone at the source of sound
  • Set the microphone in a typical listening position, but normally closer
  • Listen to what the microphone sounds like, then adjust the position, re-adjusting until the sound is as good as it can possibly get.

Of course there's a lot more to it than that, particularly where multiple microphones are concerned, and there are a few exceptions such as ambience mics. But these few short rules of microphone positioning will get you a long way along the road to success.

But what about PA system speakers in live sound?

Again, there are a few simple rules that will get you a long way.

The first is to…

  • Point the speakers at the audience.

This should be obvious, but judging from the number of times I've seen loudspeakers pointing in all kinds of directions, even in professional installations, it is a point worth making.

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There is a refinement to this…

  • Point the speakers towards the audience and, as much as possible, away from the walls and ceiling.

The audience will absorb sound, which is good. Walls and ceilings will reflect sound which, unless they are acoustically treated and that treatment has been done properly, is bad. It's bad because it creates strong reflections that mingle with the direct sound making the overall sound less clear. Some reverberation is OK, but hard so-called specular reflections are always a bad thing.

Of course, you might be working outdoors, in which case there may be no walls nor ceiling to worry about. But pointing the speakers towards the sky would be a waste. Point them at the audience. It really does make sense.

What about height?

This is a good question. Ideally people at the back of the audience should receive sound that is just as good, and just as loud, as those at the front.

In theory, the way to achieve this to the best extent possible would be to have a highly directional loudspeaker mounted horizontally a long way above the center of the audience. It would cover them all almost equally.

The main problem here, among some smaller ones, is that the audience expects the sound to come from the stage, not above. So the answer is to compromise. Mounting the speakers on stage but higher and angling them down will achieve a more even coverage than setting them up at stage level.

There is such a question as 'how high is too high?' The answer to that is that it is highly desirable for the sound to appear to come from stage level. Raising the speakers raises the source of sound. So a judgment call has to be made. How even should the distribution be from front to back, and with what degree of realism should the sound appear to come from the stage?

That's enough for now. These are key points and on top of these lie a lot of subtleties that add up to create great live sound. But if the basics are ignored, then nothing will work well.

Summary

In live sound you should aim to point the speakers at the audience and away from the walls and ceiling (or outdoors the sky). Mounting the speakers higher will achieve a more even coverage from front to back (remember to angle them down at the audience), but if they are too high then the sound will not seem to come from the stage.

David Mellor

Acoustics

Acoustics

In this course, trainer Joe Albano explains how sound interacts and is modified by the listening environment. Learn the powerful influence of acoustics on our perception and the propagation of sound.

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David Mellor