Drum Track Processing Tips, Part 2: Compression
This is the second installment of my series of articles addressing the processing of drum tracks. My focus here is on compression.
I tend to use compression for two distinct reasons – either to color a signal or to control its dynamic range. While I much prefer hardware, software can get you there too. Rather than functioning as a technical manual on how to use a compressor, this article will touch upon some desired approaches regarding drum track compression.
Let me first mention that 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 tracks I’d recommend sticking with FET’s or VCA based designs, although you can get anything to work if you try hard enough.
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 drum track, you can control how much articulation or “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” in the kick drum track? Crank up the attack and slow down the release. Here the initial click is caught and tamed while the tone of the shell is boosted. This is a way to EQ the signal without resorting to an actual EQ. You are essentially manipulating the attack and sustain of the drum tracks in order to produce more bite and punch, or conversely, to round off transients for a more mellow, round sound. Stylistically speaking, Modern Rock drum 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 to drum tracks, but to me the key to proper compression is entirely in the manipulation of attack and release. If you’re using an LA2A, forget what I just wrote and carry on.
The other reason compression is employed is to simply reduce a signal’s dynamic range. For instance, perhaps you have a snare drum track that has varying intensities in amplitude (meaning the session drummer hit some notes harder than others). If you want a more consistent level or placement in the track, you may want to slap a compressor on it to keep the output consistent. You could also place a limiter on the snare drum track. Here a limiter would keep the snare from spiking into the red (overloading) while 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 especially loud 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 gets your sound, but dual Mono seems more exciting and natural. It allowins the drum tracks to “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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