This is the second installment of my series of tutorials on 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 better, but of course software can get you there. I won’t go into great lengths about how to use a compressor but will touch upon some desired approaches regarding drum track compression. There are four different types of compressors: Vari-mu (Delta-Mu), VCA (voltage controlled amplifier), Electro-Optical (opto), and FET (field effect transformer). For processing drums I’d recommend sticking with FETs or VCA based designs, but 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, you can control how much beater “click” you hear versus how much “body” and thump is heard by compressing a kick (bass drum) track. Should you want more “snap” out of a kick, simply slow down your attack to allow more of the initial transient through. Need more “bloom” (shell) in the kick drum track? Raise the attack and slow down the release. Now the initial click has been 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 essentially manipulating the attack and sustain of the drum tracks to produce more bite and punch or to round off transients for a softer mellower sound. Stylistically, Modern Rock drum tracks seem to beg for massive amounts of compression, while Jazz and Folk tracks prefer to be untouched.
Ratio and threshold are also definitely important to drum tracks, but to me the key to proper compression is all in the manipulation of attack and release. If you’re using an LA2A, never mind what I just wrote.
Okay, so the other reason compression is employed is to simply reduce a signal’s dynamic range. For instance, if you have a snare drum track that has varying intensities in amplitude (meaning the session drummer played some hits harder than others) and you want a more consistent level or placement in the track, you might want to slap a compressor on it to keep the output constant. You could also place a limiter on the snare drum 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 and you may find that just a touch of compression here and there can help reign in unruly hits. If your goal is to present a more honest and natural drum sound, then slight hints of compression at low thresholds and low ratios will be the prescription of choice. Should you decide to strap a compressor across the Drum Bus, I would recommend keeping the compressor in Dual Mono as opposed to linking the compressor in Stereo. Use your ears and decide for yourself, but Dual Mono seems more exciting and natural – allowing the drum tracks to sort of leap out of the speaker during fills and crashes.
Remember, experimentation is key with compression of drum tracks. Have fun and be sure to read my other articles in this series which address gating, parallel compression, equalization, and other concepts.
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