Compression 101

Compression in my honest opinion is one of the more difficult features in mixing to completely understand and master.  But when it is mastered, it can be a secret weapon to achieving that professional recording studio sound.  Too many people now a days on forums and YouTube comments are asking “what are the settings that I must use on my compressor to make my voice sound good?”  So many things are wrong with that question. Lets Start off with the preparation.

First of all, be sure that before you even think about mixing anything or throwing any plugin on any audio track, make sure that the track is the best sounding take that you can possibly have.  Here are a few tips to assure that you have a track ready for a mix:

1. The wave form is even.  Be sure that there are no major spikes or cut outs in the wave form and check to see if the dB level is even, and there is no clipping AT ALL.
2. Was the vocalist/amp/guitar too close or too far from the mic? Proximity effect plays a big role here.  This is when a mic is placed too close to the sound source, resulting in overwhelming bass frequencies that you do not want unless that is the sound you are looking for.  On the other hand, being too far from the mic can give you a distant sound in the recording, which can be useful when creating space in the mix.  But if you are recording an IN YOUR FACE rap vocal then you want to be closer to the microphone.  Just be aware of the almighty proximity effect.
3. Clean up the audio.  Once you have a nice looking, and nice sounding audio track, go in there and clean up and trim any quiet parts.  Nobody wants to hear a background cough, or your nasty mouth noises in the mic during the epic guitar solo or instrument break.

If you do not have a track that is 90% done without the mix, the go back and repeat steps one to three.  Experiment with different mic techniques, angles and distances.  You’ll get it!

Okay now that you have a nice sounding track ready for mixing, it is time to actually mix it! Finally! The time we have all been waiting for!  Just one more thing. ALWAYS remember the golden rule of mixing:

**THERE IS NO “GIVEN” VALUE THAT ANY MIXING SETTING CAN HAVE.  IT DEPENDS ON THE TRACK, SINCE NO TWO AUDIO TRACKS ARE THE SAME.  USE YOUR EAR, AND LISTEN TO WHAT THE TRACK NEEDS**

I can not stress that enough.  Listen to what the track needs and you will receive a better result than any settings your find on any forum.  For beginners, start off with a preset, and tweak it until it sounds perfect. EXPERIMENT EXPERIMENT and EXPERIMENT some more!

So what is compression anyway? Think of it like this:

You and your family are moving down south and you have a big rental truck.  You have to put all of your stuff in to that rental truck.  You can fill that baby all the way up, shoving things into the little crevices until there is no longer enough room for anything else.  But once that truck starts moving, all over your stuff is going to get scratched up, broken and ruined.  Think of your audio track (make sure it is clean and well recorded! You don’t put garbage in a moving truck? Do you?) as the things you are loading into the truck, and the truck as the compressor.  If you overdue the compressor (put too much into the truck), then you will crunch and ruin your audio (the things you are moving).  So this is key.  Unless you are going for a squashed, over compressed sound, do not over due the compressor.  Now time to go more in depth:

A compressor’s role is to reduce the dynamic (volume) range of the audio file or instrument onto which one is inserted, effectively lessening the volume gap between a part’s quietest and loudest moments. It’s easiest to think about this when a compressor is applied to a long, dynamic part such as a lead vocal, though of course an individual drum sound has a dynamic range too—these start with a loud initial hit and fade to silence, so drums have a wide dynamic range, it’s just that this range plays out over a short period of time.  Generally there are 5 basic parameters on every compressor:

Threshold

Sets the decibel (dB) threshold to the level at which the compressor begins to work. If you set it to 10 dB for instance, any signal coming in above that will be have its ass shaped by the compressor according to the parameters below.

Ratio

This sets the amount of compression, in dB, applied to a signal once it violates your pre-set threshold.  A ratio of 4:1 will output 1 dB for every 4 dB of input signal that exceeds your targeted threshold

Attack

The time, measured in milliseconds (ms), it takes for the compressor to reach its maximum level on the sound.  A fast attack can be useful for damping percussive peaks so the overall track level can be increased. Can also add punch to a track.

Release

Controls how long (ms) it takes to release a signal from the compressor once it dips below your specified threshold.

Output

Sets the overall output level of the effect (dB). This can be useful to whack up the output level again after its been reduced from applying compression to a signal – this is otherwise commonly known as make-up gain.

There is a basic outline for these settings that will help you begin to experiment with them.

So now it is important to experiment with all of these.  Remember, nobody can become a professional mixer or engineer in one night by using presets or settings from a forum.  It all depends on what sound you want to achieve and what your track is calling for.  My next article will go more in depth on creating space in a mix so your instruments do not sound cluttered.  Be sure yo read my article on Understanding EQ and I will see you soon! Keep making music!