It's been said before that recording is an art form. Well, it's true. Recording, just like anything else take lots of patience and practice. Most of the tools used in the recording process can be pretty straight forward. You buy a new multi-fx box, plug it in and switch on, dial in that "Hall Reverb" preset and....Yea baby, that's straight forward. Unfortunately, after purchasing your new compressor, you plug it in and switch it on and..........now what? Applying compression is a very subjective kind of deal. When compression is used correctly is meant to be a subtle affair. Sometimes the difference between a good recording, and a professionally polished one, is how the engineer applied compression to his or her tracks.
The magic box
Compression for those that have never used one or even heard of the process, is a necessary evil I'm afraid. Compression enables us to control the dynamic range of a signal. Compression also fools the ear by increasing perceived loudness of a signal. By that I mean, it makes the softer parts of your signal louder, while making the louder parts quieter, thus making the signal more consistent. When applied correctly, compression helps us tighten our tracks, making them fatter, and with a more controlled dynamic range, helps us to weave all the track elements together in our sonic landscape. The problem though, is sometimes when running a signal through the compressor, by the time you really hear it working; you may already be in the danger zone of over doing it. Think about that one! Also, it's worth mentioning that a lot of engineers compress some instruments lightly on the way into the multi-track or DAW. Thus, by turning down the louder parts of your signal, and turning up the quieter parts, you can then increase your over al level to the recording device. The mixing engineer will be applying even more compression (trust me) during the mix stage. How much compression to add on the front-end will depend on the signal itself, (i.e. bass, voice, etc.) the style of the music, and the dynamic range of the signal being recorded. Hopefully the recording engineer would not slam the vocal or instrument too hard at the beginning of the recording process, as this will leave the poor mixing engineer with a posible train wreck with no options at the end.
Aladdin's Lamp?
When you think about it, the controls of a compressor are simply asking you, the operator, basic questions to help it, the compressor, fulfill your commands and desires. One of the first questions it's asking is "What ratio setting master?" If you are new to compression, and want a hotter signal going to tape or workstation, a safe bet is a 2:1 ratio to 4:1 ratio. There are very clinical in depth resources on the net for examining what the term "ratio" means, but the theory is, the higher the ratio, the deeper the squash. Speaking of squash, the comp/genie will now ask when to apply said squashing, so it's time to reach for the threshold control. Threshold tells the compressor "this is the point I need you to apply that ratio I told you about earlier." When the signal gets above the threshold, that's when the compressor will begin kicking in.
Shall we attack, my master?
Next, the comp/genie will ask about attack and release settings. I think this is where most folks get stumped because the controls on our comp/genie do in fact all inter-relate with one another. If I want to find my perfect attack time, I will start by setting my release control (yes, release) for a half second to a second just as a reference point. The attack control is the comp/genie asking the question "Once the signal goes above your set threshold Master, should I let some of the signal through before I start the squeeze?" In most cases the answer is yes! With the attack time set at the comp/genie's fastest setting, the instant the signal goes above your set threshold, the compressor will bite down with shark-like precision, which in the end can make the sound of the signal rather dull and lifeless. Keep in mind here; there is no magic setting, so you need to use your ears. By slowing down the attack, you let parts of you signal through (in milliseconds, so keep that in mind) before the comp/genie will finally kick in. The effect can be down right magical. You might have a gain reduction meter on your box. This meter will tell you when the compressor is working, and when it's not. You are safe if the loudest parts of your signal hits at no more than -3db of gain reduction.
When to let go.
I think we can all agree that there is a vast difference in the decay time of a sustained bass note, verses the tap on a snare drum. Therefore one release time will not fit all. The release setting is the comp/genie wanting to know when to release its death grip on the signal once the signal falls below our threshold. Again, you will need to use your ears. If the signal were to be quickly be compressed, and immediately released, the result would sound very unnatural to say the least. If your signal is a bass guitar, then if your release is still between a half second and one second, depending on the style of the music being recorded, the release may be fine just where it is.
But where's the magic numbers?
Sorry, there are no magic numbers. But maybe there is a good starting point. For light duty compression patch in your compressor, let's start with a ratio of 2:1, have the musician play with intensity that he or she will be using during the recording. Start tweaking the threshold to where the gain reduction meter kicks in at no more than -3bd of gain reduction only on the loudest parts the player is playing. For those that have to have numbers for the attack and release time, I might start with a 5ms attack and use your ears to fine tune from there. Release, I would still set at a half second to a full second to start but ask yourself, does this instrument have a fast decay, or a slow decay. After using your ears to fine tune, if it sounds right, then it is right!
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