Compression.

It can seem pretty intimidating at first.

In fact, when I was just starting out, and before I had any mentors, I had no clue what it even was, or why I was supposed to use compression.

So I didn’t.

Yeah…that’s probably a big reason why music stunk…

But if you don’t already know, compression is super important!

Compression is one  of the very foundational elements of mixing.

In fact, you’re most likely going to want to put a compressor on every single track in your mix. Whoa!

And when I first learned this, I just started throwing compressors left and right, and strangely…they didn’t really seem to be helping…

This is because I didn’t know what I was doing. A tool is only as good as the craftsman wielding it. If you don’t know how to use a hammer, you’re never going to get that nail into the 2×4.

I want you to avoid that pain, and so in this post I’m going to break down for you the essence of compression, and how to best use it in your mixes.

Compression is Basically a Smart Volume Fader

Think of a compressor as a robot. It’s a nice friendly robot that wants to help you with your mix!

This nice friendly robot is awesome because it can super quickly turn the volume of a track down automatically.

And that’s pretty much it! That’s all compression is!

How Does One Use The Robot?

So now you may be thinking:

“Okay, cool, I’ve got a smart friendly robot that can turn down the volume on a track really fast…but how do I use this in my mix?”

Well, the ability to turn down audio automatically and strategically exactly when you want gives you great power.

For example, you can tame loud peaks in audio and leave the rest of the sound unaffected.

Ever felt that a track got too loud in certain parts, say a vocal, but if you turn the volume down now the rest of the track is too quiet?

This is a prime situation for a compressor. The compressor will turn down the loud parts, but leave the rest of the vocal just the way it is!

All the compressor is doing is turning audio down, or, “compressing” it.

But when exactly does that robot kick and turn down the audio? And how much does it turn it down, and for how long? You get to decide.

Compressor Controls:

Threshold:

The threshold determines when the compressor kicks in. Until the audio signal level (loudness) reaches a certain height (the threshold) the compressor won’t do anything.

So make sure to set your threshold at a level where the audio signal actually reaches it so that it can actually start compressing.

Ratio:

This is how much the signal is compressed. How much the robot turns the volume down once this signal passes the threshold.

So if your ratio is 3:1, then the compressor will compress it down by 3.

The higher the ratio, the more extreme the compression.

Ratio and threshold work in tandem. In fact, many compressors will only have these two parameters and nothing else.

Attack:

This is the amount of time you give the compressor to kick in after the signal reaches the threshold. For example, once the threshold is reached, do you want the robot to turn down the audio immediately, or do you want it to delay a little bit?

Choosing the correct attack time is critical for shaping sounds because it can change the way the transients of the audio signal are affected.

Release:

This is the opposite of attack. Release is when your robot decides to stop compressing. A fast release time means that the compressor will shut off fast. A longer release time means it keeps the signal compressed for longer.

Make-up:

This allows you to turn the volume back up to account for the loss of volume you experience with compression. For example, you may want to turn down only certain sections of a track, but you don’t want to lose the overall loudness. This helps to smooth the signal out.

Knee:

There are two types of knee, soft and hard. The knee changes the way the compression is applied.

Soft: The compression is applied gradually as the signal approaches the threshold

Hard: The compression is applied linearly as soon as the audio hits the threshold.

Input/Output

This is important for gain staging. For example, if you have a very quiet signal, it can be helpful to turn the gain up so that there is enough signal entering the compressor, or vice versa if the level is too high and you can’t put the threshold low enough.

A good rule of thumb is to increase the output according to the amount your compressing. In other words, if you are compressing 3 db, increase the gain by 3 db.

Another good guideline to follow is to make sure you aren’t getting drastic level differences when you bypass the compressor.

Our ears are hardwired to think that louder generally sounds better than softer, so don’t fool yourself into thinking a track sounds better with your compression when all you’ve really done is turned up the volume. So when you compare your track with compression and without, you want the volume level to be about the same.

To summarize all that, a compressor is a wonderful tool that gives you the ability to smooth things out, and allow your tracks to sit well in the mix so they don’t clash, and are also all present.

So, when do you use compression?

Well, it depends on what situation you are facing in your mix.

Compression is a tool, not magic fairy dust. Use your ears, and listen for what your track needs.

Is that snare drum ringing out too much? Then set up a compressor with a longer attack, medium release, and a robust ratio to diminish that.

Do you have a vocal track with some really short but blaring sections? Then set a higher threshold that only hits those highs with a fast attack and release.

It really depends on your situation.

But don’t be intimidated by all the knobs and their weird titles. It’s pretty straight forward. What is most crucial is developing a critical ear, and being able to determine what a track needs.

On top of that, a lot of compression decisions will come down to taste as well.

So get out there, start experimenting, and start compressing!

What is your biggest struggle with compression?

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