Loudspeakers are designed to handle a certain level of volume. Once they pass a certain level, they will distort the sound and if prolonged, will eventually fail. (The latest newsletter goes into more detail on loudspeaker failure.)
Regarding preventing loudspeaker level distortion, you need to know a few pieces of information; the maximum volume your loudspeakers can handle, the average volume your church service or other gig runs, and the level of the loudest part of the service/gig.
You can then determine how much headroom you have in your production. This headroom is the measurement of the difference between the average sound produced out of the sound system and the loudest output level the system can handle.
If your average volume level is 90 dBA and your loudspeakers can only handle 120 dBA, then you have 30 dB of headroom. You can prevent loudspeaker distortion by watching your sound meter readings when you get to the loudest part of your event and reducing the board (console) volume to keep it under the limit. You can also use a compressor to do this effectively as long as you aren’t overdriving your compressor, which can also lead to a distorted sound.
A common question I receive when I hold a training session has to do with the channel/board level peak lights. The question comes in the form of “is it OK if the clipping light comes on?” or “isn’t it bad if the channel is clipping?”
Clipping is a sign the signal level is too high. A channel with occasional clipping isn’t an issue. A singer suddenly belts out a word louder than the others or a drummer let’s his sticks hit a bit harder. That’s OK. Most of the time, this sort of clipping isn’t going to be noticed.
A channel showing consistent clipping means you need to lower the channel volume or if you caught it during sound check, you can reset the gain structure for that channel.
Board (console) clipping works much the same. Occasionally, it’s OK but anything more than that and you have to re-evaluate your board input levels. I would go as far to say if your board level is clipping in any form, then you should look for the source and see what you can do to eliminate it. Clipping is an extra audio process that can negatively affect your sound.
Distortion produced by faulty equipment isn’t a matter of “how do I stop it” as much as it is a matter of “what do I do know.”
Consider the impact of removing the equipment from service. Will its removal have a drastic affect on the quality of the sound? I’m talking about “will the congregation notice the difference.”
With this information in mind, you should evaluate your existing equipment and determine what happens if that particular piece of equipment fails.
—Have access to a spare for swapping in?
The Take Away
Audio distortion is a sign an input volume is too high, a loudspeaker is doing more than it’s rated, or a piece of equipment has failed. Each reason for distortion has a solution which can be easily implemented.
The best part of all, barring equipment failure, you can resolve most problems during the sound check…Of course we are talking “live sound” where anything CAN happen at any time.
Ready to learn and laugh? Chris Huff writes about the world of church audio at Behind The Mixer. He covers everything from audio fundamentals to dealing with musicians, and can even tell you the signs the sound guy is having a mental breakdown. To view the original article and to make comments, go here.