It’s time to kick in 2014 with a bang, so we need to add some more tricks to your recording arsenal.
What Is Compression?
Just imagine you have just recorded your vocal and certain passages and words are quiet and soft and others are loud and energetic.
In order to solve this problem you’d have to ride the vocal fader up for the quiet sections to be heard and bring the fader down on the louder parts.
Nothing prevents you doing exactly that and in certain scenarios this may give you a more natural sound.
However, there’s a tool to do that task for you. It’s called compression.
But be careful – compression can also alter the “character” or tone of your voice for good or ill. We’ll be addressing this issue in this series.
The Old Days
Back in the day, engineers would learn the parts of the mix that needed level riding and then make those fader moves as the final mix went to tape.
You can think of a compressor as an automated channel fader.
Together with Limiting, Gating and De-Essing, Compression is part of the dynamic processing family. It controls the volume “envelope” of a sound.
A compressor is an extremely versatile and useful recording, mix and mastering tool.
Each brand will differ in the way it operates and it will differ in sound character.
Certain compressors will give you a really clean and transparent sound, so that you are compressing the signal but you don’t really notice it.
Others have a more defined sound that could help you sculpt the sound you are looking for. Tube compressors, for example, have a warm, thick character that can warm up the vocal, bass and other instruments.
More modern units can create a punchier feel that may be more appropriate for heavier hitting drums.
There are no hard and fast rules as to which compressor to use for a particular application. This is down to taste and “if it does the job, it’s right”.
Bar a few exceptions, most boxes will feature the following controls:
Threshold:The threshold sets the point at which the compressor will start working.
Ratio: This is the amount of compression you are applying to your signal.
1:1 (say 1 to 1) gives you no compression at all. 2:1 will give you gentle compression and as the ratios increase , so does the compression effect. e.g. a 4:1 ratio – for each 4dB at the input, the compressor will output 1dB. When you get to ratios above 10:1, you are, in essence, limiting the signal. It’ll get more squashed, a lot more controlled and less dynamic.
You can adjust the attack to time the compression to the music.
Faster attacks will kick the compressor in earlier, making it act more like a dynamic controller.
Slower attacks allow the initial transient of the signal to come through and then control the tail of the sound.
Attack times can range between 0.1 msec to 500 msec.
Release: The release time dictates how fast or how slow the compressor lets go of the signal. You can compare it to the release time in an ADSR envelope of a synth.
As with the attack you can time the release to the music or the rhythmic character of the material you are compressing.
Release times range between 0.05 sec to 5 sec.
The release and attack controls combined determine how the unit is going to behave.
Make Up: The process of compression generally incurs a drop in gain. That’s why pretty much every compressor has a make up gain section to compensate for the loss.
Next time we’ll be looking at the pros and cons of compression as a vocal effect…