7 essential compression tips

Compression is one of the most indispensable tools available to today’s producers, enabling instruments and vocals to become punchier, louder and more consistent, often exerting a positive ‘analog’ influence on the character of a sound. Thanks to the power and affordability of today’s virtual effects, maintaining a library of quality compressor plug-ins has never been easier, and there are hundreds out there to choose from, including the go-to SOLID and VC series.

Having the gear is one thing, knowing how to put it to work is another, and that’s where this feature comes in. Here, we’re serving up seven essential techniques and considerations to help you get more out of this cornerstone processor.

1. Use the right compressor for the job

Almost all plug-in compressors emulate one of four analogue architectures. The most ubiquitous of them is VCA (‘voltage controlled amplifier’; VC 160, SOLID DYNAMICS, SOLID BUS COMP) compression, which is best deployed for the uncoloured control and beefing-up of heavily transient material – i.e., drums and percussion, due to its super-fast response and impressive transparency. The optical compressor (VC 2A), on the other hand, works well on vocals, synths, strings and other ‘musical’ sources; while FET compression (‘field effect transistor’; VC 76) majors in speed of attack and colouration – ideal for drums, guitars and aggressive vocal treatments. Finally, the Variable Mu compressor (VARI COMP) employs a valve-based design that delivers a slow, supremely smooth response, making it a classy option for vocals, groups and the master bus.

2. Dial-in parallel compression for the best of both worlds

Also known as ‘New York style’ compression, and most frequently called on for the emboldening of drums, parallel compression is the technique of mixing the unprocessed signal going into the compressor with the compressed signal coming out of it, in order to blend the characteristics of both. Thus making the quieter bits louder without crushing the all-important transients. To make it happen, you either need to use a compressor with a wet/dry mix control, or set your plug-in up on an auxiliary bus and send the subject track to it. Crank the compression ratio up to at least 20:1 and lower the Threshold to capture the meat of the signal, clamping down on it hard; then simply reintroduce the dry signal via the mix knob or send control until you get a good blend of transient impact and overall solidity.

3. Expand your sidechain compression horizons

These days, the term ‘sidechain compression’ is part of the dance music vernacular, usually referring to the love-it-or-hate-it pumping sound created by putting a compressor on the bassline or even the whole mix, then routing the kick drum to its sidechain input so that the volume of the music drops every time it hits. But sidechaining has always had many more uses than just that, from ‘de-essing’ vocals and ducking long reverb tails out of the way of acoustic guitars, to making space in cymbal-rich drumkit overheads for the snare to cut through. Basically, it’s the technique to turn to whenever you want to control the volume and/or dynamics of one signal with another for any corrective or creative purpose, so don’t be afraid to experiment!

4. Control your compression with sidechain eq

The sidechain equalizer on a compressor lets you shape the frequencies in the detection circuit input that actually triggers compression, whether that signal is a duplicate of the one being processed (i.e., the default behavior of any compressor) or an external source – and there are two particularly notable scenarios in which this proves invaluable. The first is the application of a high-pass filter on the sidechain to reduce the influence of kick drums and heavy bass sounds on bus or mix compression, preventing unwanted pumping. The second, as touched on above, is ‘de-essing’, which – should you not have access to a dedicated ‘de-esser’ – is done by boosting the sibilant frequencies of the vocal in the sidechain signal, so that the compressor ‘overreacts’ to them, lowering the volume further than it otherwise would when loud ‘esses’ are detected.

5. Compression or eq first?

With compression and EQ so often applied in tandem, you may struggle to decide which should come first in the chain. Ultimately, there’s no right answer: either way is fine, and it really comes down to the nature of the source material and what you’re trying to achieve by processing it. For example, if you’re working on a drum loop that’s obviously all over the place dynamically, it’s a good idea to bring it into line with compression before EQing. Alternatively, if your compressor is being pulled astray by certain prominent frequencies in a guitar or vocal, EQing them down first could well be the answer. And, of course, there’s nothing stopping you from applying further compression after your post-compression EQ to iron out any newly added peaks, or another EQ after your post-EQ compressor to tame harsh frequencies that it might have brought to the fore.

6. Color your sound with character compression

In emulating the analog circuitry of real-world gear, many compressor plug-ins also introduce harmonic distortion and other inherent acoustic characteristics to the signal, yielding ear-pleasing coloration that can make all the difference in the mix. Bear this in mind when choosing the ‘right’ plug-in for a given compression task. VC 76, for example, is based on the classic Urei 1176 compressor, famed for its transistor-driven fatness and energy, and is phenomenally effective on drums; while the smoothness and warmth of VC 2A’s LA-2A-inspired valve/opto design makes it a miracle-worker on vocals. Some virtual compressors afford a degree of control over the amount and type of distortion applied, such as SUPERCHARGER GT, which is equipped with three flavours of variable tube saturation for great timbral flexibility.

7. Don’t compress for the sake of compressing

As contradictory to everything we’ve just said as it may at first seem, this last one can’t be overstated: you don’t have to compress every sound in your mix. All too many inexperienced producers mistakenly assume that compression is invariably of benefit, even if only laid on lightly; but if ever you find yourself inserting a compressor into a channel without a specific reason for doing so, don’t. Compression was originally invented as a problem-solving technology – an automatic alternative to manually riding the volume fader – and even though it’s found plenty of creative application beyond that over the decades, it is still, in essence, intended for controlling volume levels. If your sound in question is already consistent and ticking all the right dynamic boxes, or – more importantly – it actually works because of its unfettered dynamism, leave well alone.