Myth #4: Compression reduces dynamic range

How many times have you read this particular nugget of wisdom? And sometimes it’s true. But not always. Indeed sometimes it’s important that it’s not true.

Imagine a mix in which kick, snare, and cymbals/overheads feed a drum bus. The intuitive thinking goes something like this: if I slap a compressor on this bus and compress it, by definition I’m going to be pushing down the loudest stuff and as a result the dynamic range will be reduced. That’s what compression does, right?

Yes, and no.

Yes, a compressor can and does push down on the loudest stuff. But no, that doesn't mean the dynamic range is automatically reduced.

Yes, a compressor can and does push down on the loudest stuff.

But no, that doesn’t mean the dynamic range is automatically reduced, and here’s why: if your attack is slow enough, the bulk of the transients will still come screaming through even though the detector is simultaneously screaming at the gain circuit to ‘TURN IT DOWN!’ Then, if your threshold is low enough and your ratio is high enough, what does get pushed down gets pushed down so far that the resulting signal is much quieter than it would have been if you hadn’t compressed it at all.

The result of those two factors: the loud stuff is just as loud (albeit for a shorter time) and the quiet stuff is quieter. Which is to say that your dynamic range is now increased as a result of the way you applied the compression.

Engineers exploit this reality every day on their drum buses; the classic trick is to take a comp set to a medium or high ratio, slowest attack, fastest release and dig in hard. With a deft set of hands and ears, the result is a track that, on its own, is an unusable series of fast, dead-sounding thumps and pops that herald each drum hit in a highly exaggerated but uniformly level manner. This track is then blended in parallel, usually quite subtly, and the result is a palpable increase in the perceived impact, punch, warmth, and consistency of the drum sound.

So yes, compression generally does reduce the dynamic range, but it doesn’t have to, and sometimes it does exactly the opposite to wonderful effect.

Myth 5: Compression makes sounds bigger

This final myth is very personal to me.

I had the pleasure of attending an early Mix With the Masters seminar hosted by one of the acknowledged masters of mixing and, in particular, artful compression, Michael Brauer.

At one point the group was talking about compression, and someone asked Michael what he’s listening for when dialing in one of his elaborate compression schemes (if you haven’t read up on his multi-bus and five-compressors-as-one-vocal-comp techniques, you should; even if you never try them your brain will appreciate the novel approach).

pushing a sound into a compressor is like pushing an object into a stretched rubber band

This is my interpretation of what he said (and I’m OK repeating it here because I’ve since read it in interviews he’s done): pushing a sound into a compressor is like pushing an object into a stretched rubber band. The harder you push the object, the more the rubber band pushes back. Michael listens for the point where there’s a musical push-pull movement and the comp feels springy and flexible.

Not pushing enough results in too little resistance – no interesting movement. But push too far and the rubber band loses its elasticity and becomes stiff – the sound loses its life. What’s more, when you push too hard into a compressor the sound becomes small.

When he said that last bit, I remember jolting upright in my seat because I’d never previously felt like I had a masterful grasp of when to stop laying in with a compressor. I had become pretty adept at using ratio and release to control the transparency or audibility of the effect, and I was starting to feel confident in knowing what kind of attack served the sound in the mix. But where to park that threshold was still a mystery to me and had been for a long time. This nugget of insight felt like the key to solving that puzzle.

if I was squeezing a sound and it got thicker, I thought that was the same as making it bigger

When I got back to my room in the States I immediately laid into my compressors and started listening not just for snap and swing but also for size. I became obsessed with running every track I had – every sound and bus, even my FX – through the different comps in my rack and plugin folder. I relentlessly tweaked them in all kinds of ways – aggressively, musically, invisibly, whatever – constantly level matching and bypassing the comps to listen for one thing and one thing only: how big or small the sound became in the context of the full mix.

What I heard was a revelation. I realised I had been confounding ‘density’ with ‘size’. That seemingly small syntactic error had huge ramifications, both on my productions and on my experience of creating them. This mistake explained why I never knew when to stop digging in with a compressor.

Here’s what that mistake looked like: if I was squeezing a sound and it got thicker, I thought that was the same as making it bigger. I was enamoured with the ‘grr’, the ‘hair’ and the urgency that compression added to my sounds. When I bypassed and that density went away, I was resolute that the compressor was improving things.

Wrong.

The problem with making density your primary compression benchmark is that you can keep going as far as the comp will let you; if urgency is a drug, compressors are the dealers of the stuff. And they have no conscience; they’re happy to dose you up as often and as hard as you’re willing to go.

Ultimately you don’t want every sound to be as dense as possible

But mixing is a game of balances. Of relentless trade offs and compromises. Ultimately you don’t want every sound to be as dense as possible; instead, you want it to be as dense as necessary to transmit the emotion… and no denser.

That means attuning your ears to the proportionate spaces around each tone like the curves and twists of the pieces in a jigsaw puzzle, filling up the spectrum where necessary while preserving enough dynamics to allow the sounds, and with them the entirety of your mix, to breathe – to have air around the elements such that you feel the impact when those spaces contract and the sounds collide.

Everything in a mix must be shaped with complete awareness and respect for every other piece in the puzzle… or it won’t fit. It won’t assemble into the vivid picture that the song wants to be – a gripping story the listener wants to surrender to from start to finish.

 

Gregory Scott is an engineer, producer and the owner of Kush Audio.

10th September, 2015

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