Have you ever wondered why your buddy’s kick drum has more ‘oomph’ than yours? Are you struggling to make a certain sound pump through your mix clearer without having to increase the volume drastically? What you need is compression. And that’s exactly what we’ll be covering in Part One of our ‘How To Use Compression’ series.
What Is Compression?
Compression is used to control the dynamic range of a sound. Simply put, it decreases the difference in volume between its loudest and softest parts. The sound we’re talking about can be a single instrument or synth, a percussion loop or even entire tracks. In most cases, this is done by pressing together (or squashing, if you will) the loudest parts of the sound. That’s what compression does. It compresses.
What Does Compression Do?
Let’s use vocals as an example here. Have you ever tried to balance an extremely dynamic vocal in your mix through volume adjustments only? Chances are it didn’t work out too well. Whenever the loudest parts of the vocal were at the right volume, the softest parts were inaudible. And whenever the softest parts were at the right level, the loudest parts were making your ears explode. It’s a fairly common problem and compression is the answer.
By compressing a sound, you’re turning down its loudest parts only. Now, we hear you thinking that this only causes the sound to become quieter. This is true, but there’s one thing that you’re missing. If you were to turn up the volume of the entire sound afterwards until its peaks are as loud as before, the quieter parts will have become more noticeable. The dynamic range has been decreased and the average volume is higher, even though the peak volume is still the same. Now, the sound is much more audible and pierces through the entire mix a whole lot better.
How Should I Use Compression?
It’s fairly safe to say that the above is what makes compression an essential tool in any producer’s arsenal. But that is not its only use. Compression can also be used as an obvious effect, adding character to a sound. By using compression in the right way, your sound could become fuller, richer and even punchier. It all depends on the settings, which we will cover fully in Part Two of this series. For now, we’ll describe the most common settings on a compressor:
Threshold is a vital setting in all compressors, whether hardware or plug-in. It determines the volume level above which compression is applied and is usually expressed as +/- (plus/minus) dB. This means that if you were to set your threshold at -20 dB, compression will be applied to all parts of the sound that exceed that level. Be advised that there is no such thing as the ‘perfect’ threshold setting. It all depends on the sound input and what you are using compression for in that particular instance.
The ratio determines how ‘hard’ you’re squashing the parts of a sound that exceed the threshold level. For example: if you’ve set a ratio of 8:1 and the signal is 8 dB over the threshold, the final output will be only 1 dB over the threshold. In case you’re wondering, that’s a whole lot of compression.
Alternatively, if you’ve set a ratio of 1.2:1 and the signal is 1.2 dB over threshold level, you will also be left with an output of 1 dB over threshold level. But this time, there’s only some subtle compression.
Although not all compressors have implemented this feature, we’re still going to discuss this one. Gain Reduction isn’t an actual knob or setting, but is simply a unit of measurement that allows you to easily check how much compression you’re actually applying. Let us take the above examples.
In the first case, where the input was 8 dB over threshold level and the ratio was set at 8:1. You’re left with an output that exceeds the threshold level by 1 dB. That’s a gain reduction of 7 dB. If you only wanted to apply some subtle compression, you’ve now discovered that you have some adjusting to do.
The attack setting is measured in time (ms) and controls how quickly compression takes effect after the threshold level has been exceeded. A very fast attack time is great at removing unwanted volume peaks, but is also very noticeable. A longer attack time might not be fast enough for those sudden peaks, but does compress the parts of the sound that follow. This is useful if you want the punch of a sound to remain untouched while still applying compression to the rest of the sound.
The release setting is also measured in time (ms) and controls how long the compressor keeps going at it once the signal has fallen below the threshold. A fast release time might give you that pumping sound, but can also sound very unnatural. A longer release time on the other hand might sound more smooth, but can also negate the effects of a (fast)attack time if it drags on too long. It may also affect the transients of your sound, because it doesn’t have the time to turn off in between sounds.
What Are The Pitfalls Of Using Compression
For starters, you should refrain from using too much compression until you’ve mastered the basics. Although huge amounts of compression can be very helpful if you’re aiming for an aggressive sound, we advise against it if you don’t know what you’re doing (yet). Using a lot of compression means you’re reducing the dynamic range drastically. In doing so, you could end up with a flat and dull sound that’s not very useful in general. Instead, apply compression with moderation and keep checking whether you’re overdoing it or not.
That being said, there are no rules to using compression when you’ve mastered it. Going out of the box or beyond the rule of thumb can lead to some very interesting results. You just have to know perfectly well what you’re getting yourself into. Part Two of this series might just be of use to you in that regard. 🙂