Drum Compression

The right compressor settings give you endless power to shape the sound and groove of a multi‑miked drum recording.

Have you ever entered the final stages of a mix and wondered just how you managed to use quite so many plug‑ins to get things sounding ‘right’? Did you really need 12 plug‑ins on that snare? Were you really in control of where the sound was going, or just chasing your tail? Most listeners won’t care, of course — the track will either sound good to them or it won’t. But if you’re to deliver good mixes consistently you should care, so, on noticing this trend a few years ago, my response was to take a fresh look at how I was approaching using my basic tools during the early stages of a mix.

In this article, I’m going take you through one aspect of mixing that’s a great example of how simplifying your approach can ensure you get your mixes off to a great start: compressing acoustic drums. I’ll deliberately focus my advice on getting the best results using regular, single‑band compression. By this, I mean I won’t explore things like parallel or multiband compression here, and certainly not the sort of ‘secret tricks’ you might encounter online (see the ‘Online Tips’ box for some musings on that theme!). Such techniques can have a place in modern mixes, but in my experience they tend to work better if you’ve already laid solid foundations.

Why We Compress

Before we get stuck in, though, there are a few points that I’d like you to bear in mind. Compressors are one of the most powerful and versatile tools available to an engineer, and if you’re to use them in a productive way it’s obviously important to know something about what their various controls do. If you need a good primer on that side of things, I recommend that you check out Sam Inglis’ SOS November 2021 article: 'Compression: What Do All Those Knobs Do?'

I’m going to assume, though, that you have your head around that stuff already, and will focus my advice on developing a feel for the ‘where, what and why’ of compression — because that’s at least as important as understanding how to operate a compressor!

So why do we compress? If put on the spot and asked for an explanation, most of us would probably suggest that the aim is to reduce the dynamic range of a signal, making the difference between the loudest and quietest parts of the signal less. Some might simply say we compress to ‘make it louder’ or ‘thicker’. A compressor can, of course, be used for those reasons, but it can be used to achieve far more than that too. With that in mind, I’ll take you through some examples of using compressors to achieve different things with the drums in some of my recent mixes.

Playing Dynamics

When you’re lucky enough to work with a really good drummer, by which I mean someone who can hit the drums in a controlled and consistent way, the playing dynamics should already be on point. But away from the world of A‑list mix engineers and session musicians, you’ll find that not every drummer is up to that standard! Many of us, then, will often reach for a compressor to ‘even out’ the performance. The aim is to create the impression/illusion of a more consistent performance, and a mix I worked on recently provides a good example...

A close‑mic snare recording of an inconsistent drummer, pre‑compression. The same snare recording after compression.Happily, the drummer was decent enough to play coherent, nicely thought‑out drum parts and to keep time well, but they seemed to have less control over their playing dynamics; some hits were too loud, some too quiet. The aim in such a scenario is to reduce the dynamic range of the performance, and typically to do this you need to lean on faster attack times and higher ratios. This way, louder hits are reduced as they rise above a compressor’s threshold but the gain reduction backs off to leave the drums’ sustain alone. In this case, I started with a 5:1 ratio, a fast attack (which I fine‑tuned by ear so the part didn’t sound overly squashed) and a medium release. With the threshold set to give up to 4‑5 dB of gain reduction, the snare drum felt more consistent.

There are pros and cons to this approach, though. It works well when used fairly lightly like this, but when the amount of gain reduction increases past a certain point it starts to introduce unpleasant side‑effects, such as overly squashing any cymbal bleed on the snare mic. There will always be trade‑offs — there’s no magic bullet in this scenario — but if you need to take the gain reduction further, a good strategy can be to layer smaller amounts of this sort of compression, applying it at multiple points in the drum mix’s signal path. You might have only 3‑4 dB of gain reduction on the close mics, for example, followed by a few smaller amounts on a close‑mics bus, which then goes into an overall stereo drum bus compressor and maybe a touch more at the stereo mix bus.

You can explore other options too, of course, including edits and drum‑replacement software. Edits are probably a better approach if the levels vary wildly — largely because this means the tonality will likely vary significantly too, so taking a good hit from elsewhere solves that problem. But in my experience drum replacement tools tend to work dramatically better when I first get the recording sounding as convincingly like a strong performance as I can.

By playing with the attack and release settings on your compressors, you can push a drum kit forward or backward in the mix.

Feel & Timing

I’m still often surprised by the sense of urgency that a compressor can inject into a drum part, or how it can push the drums back or nudge them forward in a mix. It’s the attack and release controls that enable you do this, by shifting the emphasis of a drum sound more onto its initial transient or, conversely, suppressing it to bring out more sustain.

We hear a lot of talk about ‘transients’ in drum sounds, because this initial ‘point’ of each hit plays a huge part in their perceived impact and in the internal groove and feel of a drum part. It’s tempting to think that we’ll always want slow attack times that allow the transient through, but I’d encourage you to challenge your habits and experiment with different attack speeds. I’m often surprised at what settings seem to work well, particularly when applying compression to the whole drum kit.

In another recent project, the band kept stressing to me that they wanted a ‘sense of tension’ to be brought out in the verse sections’ drums. After exploring a few different options, I found that the attack and release times of the stereo drum bus compressor seemed to give me a small but appreciable amount of control over this characteristic. Changing the attack setting, in particular, affected the balance and feel of the kick, snare and hi‑hat in this submix.

Tone & Glue

In a well‑balanced drum recording, some drums will always trigger gain reduction more often than others do. When applied across a whole kit, for example, a compressor with no side‑chain filtering engaged will be far more sensitive to the kick drum than it is to the cymbals. Although the gain reduction is being applied to the whole kit including the cymbals, the compressor will react far more often to the kick and snare hits than to the cymbals. While this might not sound desirable, it can be used to create the sense of a kit that feels more ‘whole’ or ‘glued together’.

A fast attack on an outside kick mic enables a compressor to bring out the low‑end tail of the drum to great effect.

You can also use compression on multi‑miked individual drums to shape their tone — it might even lead you to do less EQ’ing. In another recent project, for example, I’d decided that the kick was the most important element to sit in the drum mix. An inside kick mic delivered lots of attack and an outside FET 47‑style mic picked up more low end. For the inside mic, a compressor with a slow attack and fast release pushed forward the very front ‘attack’ part of the sound. For the outside mic, I used heavier compression (upwards of 6dB of gain reduction) with a fast attack and medium release, so as to emphasise the low‑end ‘tail’ more. When balanced against my overhead mics, this created a weighty kick sound with an almost hip‑hop‑style low end — and all without me needing to add any extra low end with EQ; it was simply down to manipulating a good recording with compression.

Parallel compression has become a popular tactic... but I often find that it’s not needed if you first make the effort to apply compression to individual tracks in a targeted way..

Pumped Up & Excited

If the material is suitable, you can get really heavy‑handed and go for generous ‘pumping’ gain reduction. In fact, I find that this can be one of the most gratifying effects in drum compression. Typically we go down this route because we want things to sound bigger, with more energy and excitement, though actually the results can range all the way from a subtle impression of the drummer hitting things more enthusiastically to full‑on distortion. It’s also important to understand that over‑compressing drums can easily make things sound smaller too, especially if you kill the initial transients of your snare and kick and/or eliminate the natural playing dynamics in the process. (Parallel compression has become a popular tactic for avoiding this, but I often find that it’s not needed if you first make the effort to apply compression to individual tracks in a targeted way.)

Using aggressive compression on a mono room mic to create energy and excitement.

Assessing the tracks in another of my recent mix projects provides a good example. There were a few room mic options available to me and I decided that the more ‘lifelike’ stereo room channels were best left uncompressed and balanced against the overheads, while a close‑ish mono room mic would give me my ‘character’ channel. I drove this into distortion using a compressor with an 8:1 ratio and fast attack and release times. This tactic brought an explosive energy and vibe to this drum mix that worked very well at certain points in the song. My close mics were also quite heavily compressed (though not to the same degree as the mono room mic), and the key to achieving this impactful, full‑range drum mix was judging the balance between the close mics and mono room mic, and the less‑treated overheads and stereo room.

If you’d like to go down this route in your mixes, try to make a point of flipping the polarity (sometimes wrongly called ‘phase’) of different tracks from time to time to see what sounds best; heavy processing like this can alter the phase relationships between different drum mics quite dramatically (maybe for better, maybe for worse, but it often produces some creative, interesting results).

The Importance Of Routing

As you’ll probably have gleaned from my examples, I’ll often have different layers and styles of compression contributing to the final drum sound. To make this easy, you need to set up your DAW to give you control over the broader elements of the kit. I prefer not to make overly complicated templates, but I do find it helpful to treat a multi‑miked drum kit as three broad elements, each with its own group track/fader: close mics, overheads, and room/character options, each one then feeding into a master drum bus. This both reduces my options (helping me stay focused) and gives me more control once I’ve got past that initial stage of ‘correcting’ each channel. You’d be surprised by just how often you feel like the mix is going nowhere and things suddenly come into focus with a broad change of the balance. It’s hard to do this if you’re tinkering with individual tracks or have created an overly complex setup.

A simple but flexible drum bus setup.

You might also be pleasantly surprised if you experiment with the broad balance that’s being ‘pushed into’ a drum bus or mix bus compressor. Not only can riding faders into a compressor affect how much gain reduction is triggered, but shifting the broad balance as you do that can change the feel of a drum track quite dramatically. It’s amazing how often you can get a great drum sound and then bring up a bus compressor plug‑in only to find that it’s either doing nothing in terms of gain reduction or much more than you thought it would. If you have a setup that allows for quick experimentation around your own preferences, and have the confidence to go with what sounds good to you, this setup can work really well.