This is the second installment of my series of articles addressing the processing of drum tracks.
Our focus here is on compression.
I tend to use compression for two distinct reasons - to color a signal or to control its dynamic range.
Hardware is preferred, but software can get you there too.
I won't go into great lengths about how to use a compressor but will touch upon some desired approaches.
Also, there are four different types of compressors: Vari-mu (Delta-Mu), VCA (voltage controlled amplifier), FET (field effect transformer) and Electro-Optical (opto).
For drums I'd recommend sticking with FET's or VCA based designs, although you can get anything to work if you try hard enough.
First, let's talk about color.
By altering a compressor's attack and release controls, one can alter how much sustain, attack and punch a track will exhibit.
For example, by compressing a kick (bass drum) track, you can control how much beater "click" you hear versus how much "body" and thump is heard.
If you want more "snap" out of a kick, simply slow down your attack to allow more of the initial transient through.
Want more "shell" or "bloom"? Crank up the attack and slow down the release.
Now the initial click is caught and tamed while the tone of the shell is brought up.
Think of this approach as a way to EQ the signal without resorting to using an EQ.
You're basically manipulating the attack and sustain of the track to produce more bite and punch or to round off transients for a softer mellower sound.
Stylistically speaking, Modern Rock tracks seem to beg for massive amounts of compression, whereas Jazz and Folk tracks prefer to be untouched.
Ratio and threshold are also definitely important, but to me the key to proper compression is all in the manipulation of attack and release.
If you're using an LA2A, forget what I just wrote and carry on.
Okay, so the other reason compression is employed is to simply reduce a signal's dynamic range.
For instance, if you have a snare track that has varying intensities in amplitude (meaning the drummer played some hits harder than others) and you want a more consistent level or placement in the track, you may want to slap a compressor on it to keep the output constant.
You could also place a limiter on the track to keep from spiking into the red (overloading) while still preserving most of the original dynamics.
Compressing or limiting overhead mics is a common practice and you may find that just a touch of compression here and there can help reign in unruly hits.
If you're looking to present a more honest and natural drum track, then slight hints of compression at low thresholds and low ratios will be the prescription of choice.
Also, if you do decide to strap a compressor across the Drum Bus, I prefer to keep the compressor in Dual Mono, as opposed to linking the compressor in Stereo.
Listen for yourself and do what you like, but Dual Mono seems more exciting and natural - allowing the drums to sort of leap out of the speaker during fills and crashes.
Remember, experimentation is key.
Have fun and be sure to read my other articles in this series which address gating, parallel compression, equalization, and other concepts.