090 – Clipping and Signal to Noise

In live sound systems, clipping an audio signal can eventually damage a speaker. This can be expensive to replace.

Written by Scott Adamson

Clipping is bad. You don't want to clip pro audio gear. Even though there are times when clipping a specialized piece of audio equipment sounds cool (like with a distortion pedal or tube preamp), it's something that should be avoided under normal circumstances.

With live sound reinforcement, the biggest concern when clipping is speaker protection. For example, if we picture a sine wave, it has a smooth curve which will be easy for the speaker to recreate. But if we boost it too much, it can start to exceed the limits of an audio circuit, which causes the peaks of the waves to get chopped off.

Especially at high volumes (when clipping is likely), trying to make a speaker recreate this wave can cause it to fail. Imagine the speaker moving one way, trying to stop completely, then moving sharply back the other way. This can cause significant heat — enough to burn a speaker coil!

The result is either a rattling sound (which is really annoying) or total loss of sound from that speaker component. Either way, we’d need to replace it, which can be expensive and labor-intensive — if the speaker system is flown we’d have to lower it, remove the grill, replace the blown speaker component, etc.

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Clipping can prevented by limiters, which we talk about more in an upcoming post. These provide a kind of brick wall that doesn’t let a signal pass. They are very effective in speaker system processors, where they can be set to prevent amplifiers from clipping — a common way to blow speakers.

We can think of the point where an audio device (or any audio circuit) starts clipping as its maximum volume. But it also has a minimum volume, which is the noise floor.

Every audio device generates some inherent noise, even if it’s super super quiet (in digital circuits, this is called dither). And if we run a super super quiet audio signal through the device, this noise floor could make it unusable.

If we operate with a good gain structure (with our signals around unity) this should never be a issue. Just be aware: if you have a really quiet signal and you add a ton of gain, then you're also boosting the noise — which could start causing problems.

So, we need to have a strong signal compared to the noise floor — which is measured with a signal to noise ratio. And even though you won't be calculating this in your day to day workflow, it's still a good concept to be aware of.