Compression Workshop: A Little Crush

Theakston beefs up the sound of the entire drum mix by sending it via a subgroup out to a compressor, and returning the processed mix on a parallel path, such as another channel or two on the mixing board. ( Fig. 1) Blending the processed mix with the unprocessed drums adds body and presence without trouncing the original dynamics.

(Above) Fig. 1. A stereo mix of the drum set is sent to the compressor inputs via Bus 7-8. The stereo mix is compressed and the output sent back into a stereo channel and blended with the unaffected mix. This beefs up the sound without affecting the transients of the original mix.

Sometimes he opts to process only a couple of elements that he wishes to emphasize, such as the snare and overheads, and perhaps the room mikes. Adjusting the settings on the compressor to accentuate resonance and sustain on these tracks, he’ll blend them back in with the original sound. This can result in epic-sounding cymbals and an explosive room sound without influencing the kick drum sound. For that big Bonham sound, try a simple miking setup of a stereo pair of overheads and a kick drum mike, and take a copy of the overhead tracks to a compressor, squash them, and blend them back in with the unprocessed tracks.

Orlando, a punk drummer, needs his kit to cut through a mass of screaming guys and distorted guitars, so he gets a bit more heavy-handed. Compressing a subgroup of the drum mix using a fairly radical ratio of 5:1 and above, or even 10:1 or higher for a super-squashed sound, he adjusts the attack and release time to get the sound he wants. Returning this uber-compressed mix to some open channels and adding it in with the original tracks allows the drums to punch through a mix while preserving the original character and dimension of the drums.

Hip-hop producer Scanlon often uses parallel compression on the kick drum to get more punch. The low end that the compressor eats up is still present in the unprocessed track, so mixing the two together maintains the lows while accentuating the pop. EQ can be used to add more snap to the kick mix.

Scanlon will also process the snare drum to make it louder and sit forward in the mix. He goes for 10dB—12dB of gain reduction (peak squashing) by the compressor and uses the make-up gain to boost the level back up for an ultra-present snare. To add extra fatness to a snare drum, he sometimes splits the track and takes one of the two through a slight delay, and then pans the two tracks at 10:00 o’clock and 2:00 o’clock.

Another mixing trick involves layering samples underneath existing drum sounds and mixing them together for sonic variation during changes in a tune, such as a shift to a chorus. Adding, say, a brighter sample underneath the original snare or kick drum signal will add dimension to the song. Scanlon will often take samples and squash them with compression before layering them with the original track. You could either match up the samples manually, which could be tedious, or with a program like the Massey DTM (Drums To MIDI) plug-in, which analyzes drum tracks and puts out MIDI notes with velocity information.

Sound Shaping

Compression can also be used to shape sound by softening the transient and extending sustain. Overall perceived loudness decreases, and make-up gain brings it back, accentuating the midrange on quieter passages. Using a compressor to shape and fit your sound in a mix has the extra bonus of not messing with the signal phase like equalization can.

Scanlon shared a tip on how to make cymbal washes blossom using a compressor’s sound-shaping power. He cites a session where he used three room mikes 3' apart in front of the kit, and a pair of cymbal overhead mikes about a foot above the cymbals in a split configuration. During mix-down, he applied compression using a short attack time and a fast release. The short attack time squashed the peak of the initial cymbal hit, and the fast release let up on the compression quickly, bringing the resonance back up and letting the cymbal wash ring out, swelling upwards in kind of a reverse sound envelope.

Using a compressor to affect tone will invariably affect the dynamic range to a certain degree. Theakston sometimes uses Transient Designer on drums to get around this phenomenon. This is a device/plug-in that allows you to shape the attack-and-release envelope on a sound source without changing the dynamic range. SPL offers both hardware and software versions, and comparable plug-ins, include Waves’ TransX and Oxford’s Transient Modulator.

(Left) Fig. 2. This transient shaping plug-in and others like it can accentuate or soften transient attacks and affect the length of sustain, effectively bringing a sound forward in a mix or pushing it further back. It can enhance the sound without typical compression artifacts.

Theakston, who often mikes both the top and bottom of a tom and sums them together to get a deeper tone, will use Transient Designer to control the drum’s ring by backing off the sustain parameter. “It’s almost like a gate without the gate artifacts,” he says. Using Transient Designer, he takes out sustain and adds attack to make the mikes sound closer for a more intimate effect, or adds sustain and reduces the attack to make the mikes sound farther back and roomier. (Fig. 2)

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