Audio Compression Grange-over-Sands

Ever tried comparing your own recordings to tracks from your CD collection? The chances are you have noticed that the professionally produced tracks somehow manage to sound louder and more in your face than your own recordings. This is true even when you play them back at exactly the same volume. More than likely, the reason for this discrepancy is down to your use of compression - or lack of it.

Because of the way our brains work, if you play back two tracks one after another, the louder track will generally sound more exciting to our ears. It is not surprising, then, that professionals have put a lot of effort into developing the techniques of making tracks sound louder than they really are.

The tricks are all based around playing with the dynamics of recordings to increase the apparent volume of the music. One of the ways this is achieved is to use a compressor effect on individual tracks or an entire mix.

A compressor makes your tracks sound louder by reducing the dynamic range of your music, which in turn allows you to increase the overall volume of your mix before you master it to a format such as CD or MP3. Essentially, it reduces the peak volume levels in your track while increasing any troughs in the music. The overall effect is a higher and more even volume level throughout the duration of the song, which makes the music sound much punchier.

In this Masterclass, we look at how you can make better use of your sequencer's compressor plug-in. We're going to use the compressor built-in to Cubase SX, but almost all compressor plug-ins work in the same way, so you will find the tips will work equally well on other sequencer platforms.

Noise gate

Sequencers have more dynamic effects than just compression plug-ins. The noise gate is a good example and it can be a very useful tool when you are trying to achieve a professional-sounding mix.

It is difficult to record live instruments outside of a professional recording studio without picking up background noise. In fact, background noise can even be a problem when you are recording old analogue synths that tend to produce a lot of hiss when they are not blasting out notes. A noise gate is the ideal tool to cover over these problems.

A noise gate works like a compressor, except in reverse. The gate allows sound above a threshold to pass unaffected, but anything below is reduced to total silence. Noise gates have attack and decay controls that determine how the gate opens and closes, but many also have hold and range settings. The hold value dictates how long the gate will be kept open and the range value sets the level of the signal allowed to pass through the gate when it is closed.

Some noise gates also have a side chain input. This allows you to feed another signal into the gate to trigger when it is opened and closed. We've all heard this effect used by wedding DJs. They hook a microphone up to the side chain input. When the DJ speaks the music is dropped in volume to the level set by the range control. Useful when you want to know when the buffet is open; annoying when they are yelling 'Shabba' over an R&B tune! However, the side chain can be used more creatively. For example, a kick drum or a hi-hat pattern could be used to create a stuttering effect that chops up a synth pad or guitar part.

Compression as an effect

Compression is generally thought of as a hidden effect - the average listener shouldn't be aware of its presence on a track. However, you can also use it as an audible effect. From time to time, you will hear extreme use of compression on tracks to add a distinctive pumping or breathing effect. Many dance tracks employ this effect to make the music pump along to a 4/4 beat.

Author: Niall Magennis

Audio compression