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What is the difference between an effects unit and a processor? Or are they the same?

It's a wise sound engineer who knows the difference between an effects unit and a processor. Before you click, do YOU know the answer?


I must admit I hadn't even thought about this difference in terminology until someone mentioned it to me recently. And it is actually a very good way of explaining outboard devices and plug-ins without using twenty paragraphs.

Here it is quite simply...

An effects unit adds to the signal, a processor alters it.

Hey - it's a haiku! Well almost.

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So reverb is an effect. You take the original signal and tap some of it off through an auxiliary send. Feed that to the reverb unit or plug-in, which creates the reverberant signal. Then mix it back in with the original signal through auxiliary returns or channels.

You would never want to use only the reverberant signal, at least only for very occasional novelty purposes.

Compression however is a process. You feed the signal from a channel insert send to the compressor, and bring the output from the compressor to the channel insert return. You don't use any of the original signal; you use the output of the compressor in its entirety.

So, in conventional use, equalization, compression and noise gating are all processes. Delay and reverberation are both effects.

But there's a little fly in this soup. What about phasing? Normally you would feed the signal to the phaser and use the entire output, retaining none of the original.

So phasing is a process. Damn, and I've gotten so used to calling it an effect.

Even so, I think the basic concept is good as a means of explaining how these devices are generally used. I think I'll try it out for a while and see how it fits...

By David Mellor Thursday November 30, 2006