The amount of audio guys who are using compression on their drums that actually don't know how to use one properly is surprising - are you one of them? Do you load in a preset that sounds good and then leave it at that?
If so, don't be ashamed. Plug-ins are a good starting point if you're new to compressors and to be honest; I use presets as a starting point a lot of the time. The problem is, the preset doesn't know how loud your audio is or how much compression is necessary.
Therefore it's important to know and how to use the most basic parameters, so when loading in a preset you can make adjustments so the compressor is actually effective. I'm going to help you combat any confusion you have and teach you this today.
This is our ultimate guide to compression for drum recordings. It not only explains the basics of how to use a compressor, but also how to take your drum recordings to the next level by adding more punch and utilising other techniques.
What Does A Compressor Actually Do?
Let's start at the very basics. A compressor is an audio tool that falls under the dynamic processing umbrella. This is the process of controlling the dynamic range of a piece of audio so the level is consistent throughout the performance.
This is exactly what a compressor does. It's as is if you're automating the sound level of a performance, but a compressor does this much faster and of course without you spending hours drawing in automation.
Compressors can be found in many forms; as hardware rack units for studios, guitar pedals and on mixing consoles. You are probably most likely familiar with a compressor as a plug-in on your DAW.
The most basic parameters on any compressor, whether that's a stock plug-in on any DAW or a fancy piece of $1000 outboard studio gear are; threshold, ratio, attack, release and gain/make up. On a lot of compressors you will also get a 'knee' control.
Parameter Functions
Threshold - The level you set, to which you want the compressor to start working. When the level of the audio exceeds this threshold, the compressor will start reducing the levels of whatever audio goes over it, therefore only affecting the loudest sections.
Ratio - The amount of compression (level reduction) of the affected audio. Generally, most compressors go from 1:1 (no compression) to 20:1 (hard compression). Here's a few examples of the maths behind the ratio:
2:1 - For every 2dB of audio over the threshold, 1dB will come out. So a snare hit goes 10dB over the threshold and you used a ratio of 2:1, the compressor would still let 5dB out that hasn't been compressed. Therefore this gives you a 5dB (50%) gain reduction which is very soft.
10:1 - For every 10dB of audio over the threshold, 1dB will come out. So a snare hit goes 10dB over the threshold and you used a ratio of 10:1, the compressor would let just 1dB out that hasn't been compressed. Therefore this gives you a 9dB (90%) gain reduction which is much harder.
Attack - The amount of time from when the audio exceeds the threshold for the compressor to fully activate. The shorter the attack time, the more harshly the compressor will kick in. A longer attack time will bring in the compression more smoothly and gradually.
Release - The amount of time from when the audio goes back below the threshold for the compressor to stop being active. The shorter the release time the quicker the compression will ramp back down, vice versa.
Gain/ Make Up - Very simply, compressors make loud sounds quieter. In the process of controlling the peaks in your performance, the overall audio level of the channel will now most likely be quieter as a result. This is where you add some extra gain to match the audio back to the level is was originally before adding compression.
When To Use A Compressor
Compression isn't always necessary; however if your kick, snare and tom hits are inconsistent level wise you will need to use it. Inconsistent drum hits can cause half your performance to get lost in a mix.
Compressors can also be utilised to generally beef up and add some extra punch to drums, even if your levels are pretty consistent. In the section below, I'm going to explain some ways you can do this by utilising the parameters.
How To Use A Compressor On Drums
So you've decided you want to compress your drum recordings. You either have an inconsistent playing performance that needs smoothing out or you want to change the shape of your hits to suit your song.
Setting A Threshold
Load up the compressor of your choice and either choose a preset you like or start on default settings. Start from 0dB and then lower your threshold (turn up the knob) until you see the compressor working with the visual meter.
You should now be able to hear the compressor work and when watching your fader levels, they should seem less 'jumpy'. I'd personally set the threshold to activate slightly below the level of quietest section of the track. This way you're reducing the volume of the louder sections to match this.
Fiddling The Ratio
I'm not going to tell you some one size fits all ratio for each drum, compression doesn't work like that. It's entirely dependent on the amount of treatment needed and your personal preference in the sound you want to achieve.
Softer compression (a smaller ratio) will be better for those wanting a more natural sounding kit, for example on a drum cover. You may want to use a harder ratio for a studio recording to ensure nothing is lost in the mix.
If you're struggling to control the dynamics even with a high ratio, keep going back and lowering the threshold (turning up the knob) so more of the signal is being compressed.
How The Attack Affects Your Drums
Percussive sounds such as your drum hits have very short waveforms in comparison to a guitar riff for example. To control the dynamics of your drums most effectively, you want your attack to be short so the compressor kicks in before the waveform reaches its peak (loudest).
You'll find the faster the attack the softer and smoother the kick sounds. To add more punch, you will need to let through more of the transients. This is the loudest, short-burst section of the waveform at the beginning of each drum hit, as shown below.
With an attack of anywhere over 30ms, you will start to let in more of the initial hit while still compressing the rest of the waveform, therefore creating a more punchy sound that will jump out of a mix.
Keep The Release Relatively Fast
Like I said earlier, drum hits are short bursts of audio that keep coming and going quickly. It's important for this reason to have a fairly quick release time so the compressor fully stops, before re-enabling for the following hit.
Don't set it too quick though as you may choke the sound of your hits naturally fading out which may ruin the shape of your drums. A release of about 150ms is a good starting point to make adjustments
Make It Up!
Now that the audio level of this track is quieter, instead of starting a fader war by cranking that up, use the make up gain to match the volume of what the audio was prior to adding compression.
Parallel Compression
Parallel compression, also known as New York compression is a hugely helpful tool for adding some mega punch, whilst maintaining a natural feel - best of both worlds! If you have a parallel compression plug-in or preset I highly recommend you have a play with it.
What it does is it blends the compressed audio with the original, uncompressed audio. You can choose the mix/blend of these; so essentially you can make a super punchy signal and blend a little of it with the dry signal for a lively yet natural sound.
Gluing Your Drums Together
If you're compressing drums for a mix or a drum cover, a handy tip would be to add some overall compression to your whole kit after individually treating each drum/channel.
Send all your drums tracks to the same auxiliary channel via a bus and then apply some overall light compression. With each drum/channel having different types of compression and settings, this can really help glue them back together and sound as one.
Article written by Eddie at The Professional Musician Academy
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