We’ve covered compression a number of times across the iZotope universe—we have an introductory video series on the process, an Are You Listening? episode covering compression in mastering, as well as a blog on compression mistakes.
As with all things audio, there is an experimental side to compression. This is what I’ll focus on today. Here are five unusual uses for compression.
Though we’re taught to steer clear of the audio sin that is over-compression, the pumping and breathing artifacts we get from overworking a compressor can do wonders for drums that need some swagger.
One of the earliest and most famous examples of over-compression happens on the Beatles’ “Tomorrow Never Knows.” Listen to the drums and you’ll hear they’ve been smashed to smithereens—the cymbals are a wash of noise and the kick and snare are pumping right up in the front of the mix. This wild sound has become a popular one in rock, with groups like The Flaming Lips and Tame Impala who regularly experiment with nastier drums.
Hip-hop and electronic music make frequent use of over-compressed drums too. Fans of Rick-Rubin-produced music will be used to the splattering kicks and snares of the Beastie Boys. Big Beat stars like the Chemical Brothers were known to blow out their breaks with compression too.
So try this out in your own music. Go heavy on gain reduction—start with 10 dB and don’t be shy to move the dial toward 20 dB—and be sure to keep attack and release times fast enough so they grab and let go of individual drums sounds before the next hit. For a warm, round feel, go with an analog-style compressor, like the Vintage Compressor in Ozone
This is a useful technique if you want to break up the monotony of a repeated drum loop during an energetic section.
Though not exactly unusual in practice, compressing while tracking into a DAW might make some new engineers scratch their heads. Isn’t recording all about capturing a natural performance?
Compressing vocals, guitars, and drums on the way in can make it much easier to fit them in a mix. It also requires less heavy-handed compression and automation down the line.
The concern here is that the settings you pick are printed to the audio, so if you make a mistake or don’t like the results, it’s back to square one. To avoid this situation, start with a conservative 2:1 or 3:1 ratio and 3–4 dB of gain reduction. Attack and release times are going to depend on the genre and performers, but you will want to avoid fast settings that make the compression noticeable.
If you don’t want to record with compression, try tracking with a plug-in on the headphone mix instead. By narrowing the performer's dynamic range (and having them hear this version), they won’t be thrown off by their own dramatic leaps between soft and loud notes, allowing for a more comfortable, emotional performance.
Read more vocal tips: 55 Do’s and Don’ts of Vocal Production
Sidechain compression—a technique that uses one signal to control the level of another—can help producers and mixers separate instruments occupying similar frequency ranges. For example, if a deep pad keeps masking a kick in the low-mids, one might use the kick to trigger some subtle compression on the problematic frequencies in the pad.
Instead of targeting just one instrument with sidechain compression, you might want to try placing a compressor across the mix output. This will make the entire mix swell with the sidechain source and draw the ear’s attention to that sound.
This technique works well on busy, sampled material where you need to clear a lot out of way for the drums to hit hard. Check it out in the example below. The first part has no sidechain compression and it feels pretty flat and stuffy. With the sidechain enabled, the sample breathes with the beat and opens the music up.
Using the same technique described above, but muting the sidechain compression source so it’s not a part of the final mix offers up a bunch of unusual ways to add rhythmic excitement to audio.
Listen to the examples below, then scroll a little further down the page where I explain how I got the sound in the second clip. Note that the first clip doesn’t have any sidechain compression.
The pumping effect heard in the second clip is caused by a muted kick drum track that’s been fed into the sidechain input of the Compressor in Neutron (Ext Full). You can see the vocal compression happening in time with the kick in the screenshot below. Since the kick track is muted, you can’t actually hear the sound, but the compression is still present.
The kick stays on-grid for the sake of demonstration, but you can just as easily throw things off time or use an impact-heavy recording for a more experimental sound.
When you’re looking to bring some controlled chaos into a recording, send the audio to a short delay and place a brutal compressor (at least 10:1 and 40 dB of gain reduction) after it. This works well on any sound that already has a bit of roughness to it, like a crunchy snare, a raspy vocal, or mangled drums—but I’m sure you can find plenty of other uses. Have a listen to the before and after on an IDM-style beat.
So what exactly is happening here? First, the drums are routed to a return channel with a slap delay and an EQ, keeping only what’s above 1 kHz—mostly the tops of kicks and the metallic noise. In a more conventional drum kit, this would grab the tops of snares and ambient mics. Then we reach the extreme compressor in the screenshot below, which exaggerates the delay and introduces distortion and breathing.
In your own tracks, this is a useful way to create a sense of raucousness and space around sounds with a lo-fi twist. For a different perspective, I used the same setting to process a short vocal sample. You can really hear the compressor clamp down on the delay.
If you want to go beyond the “normal” ways of using sidechain, like smoothing out a performance or shaping transients, you will surely find some unusual tricks that breathe new life into your audio. The five listed in this article are a good starting point for further exploration.