Audio compression is one of the most important tools in the studio these days. Compression can bring your recordings to life and it can help to add more presence and sharpness to your overall mix.
Learning how to use and apply compression was one of the first things I learned when I started many years ago, and I still think that it’s one of the most important areas to master when producing in your own home studio.
How to Use Sound Compression
We’ve already talked about the ins and outs of what a compressor is and how it works, so here we’re going to look at how to use audio compression in your home recordings. I’ll also outline some compressor settings that’ll get you up and running straight away.
Sound compressors are mainly used in two ways:
- Control the dynamics of a recording
- Used creatively to achieve particular results
When we talk about dynamics, we’re talking about the difference between the quietest part and the loudest part of a recording, which can naturally be quite large. Audio compression reduces the dynamics and can make a track sound more even and balanced by reducing this volume variation.
Because of this smoothing of the volume range, each track can have more presence in the final mix. You’ll usually find that the busier a song is, the more compression is used when mixing to help control the dynamic ranges of all the various vocal and instrumental recordings. This means that mixing the song becomes a lot easier too.
A compressor can be used to limit the dynamics of a single track, the dynamics of multiple tracks grouped together, or the dynamics of a whole song. It can do this without there being any real change in the quality of what you’re hearing.
But it must also be pointed out that the quality of a recording can be badly affected if extreme settings are used on the compressor. Some producers I know use this to their advantage and create these extreme effects on purpose.
Setting Up a Compressor
Before you use a compressor in your studio, make sure that it’s ‘flattened‘ – that the settings aren’t affecting the inputted signal in any way. You can then adjust the device to get the sound you want.
Here’s how to set up a compressor:
- Set the threshold and the make-up gain to 0 dB
- Set the ratio to 1:1
- Set the input gain so the incoming signal is entering the compressor at a good level
- Set the ratio to the level of compression you’re looking for – some good levels to start with are outlined below
- Bring down the threshold – the more you bring it down, the more compression will take place. Generally, try not to go over gain reduction of -6 dB
- Set the attack and release as needed
- Increase the make-up gain to 0 dB output
Compressor Settings
Sound compression must be used wisely – overusing it can ruin a recording and can leave it sounding lifeless and dull. The best way to use compression is to experiment and try different settings out – after all, you may come across a setting that creates some cool new effect, or that makes one of your instruments stand out from the rest of your track.
Below are some basic settings that can get you started.
Vocals
- Ratio – 3:1 to 6:1
- Knee: Soft-knee
- Attack: 3ms
- Release: 0.4s
- Gain reduction: 4-8 dB
- Ratio – 4:1 to 10:1
- Knee: Soft-knee
- Attack: 5-10ms
- Release: 0.25 to 0.5 s
- Gain reduction: 4-12 dB
Electric Guitar
- Ratio – 4:1 to 8:1
- Knee: Hard-knee
- Attack: 2-6ms
- Release: 0.25 to 0.5 s
- Gain reduction: 6-15 dB
- Ratio – 4:1 to 8:1
- Knee: Hard-knee
- Attack: 20-40ms
- Release: 0.5 to 0.8 s
- Gain reduction: 4-8 dB
Keyboard
- Ratio – 4:1 to 10:1
- Knee: Hard-knee
- Attack: 2-5ms
- Release: 0.3 to 0.6 s
- Gain reduction: 6-10 dB
Piano
- Ratio – 2:1 to 4:1
- Knee: Soft-knee
- Attack: 20-60ms
- Release: 0.1 to 0.4 s
- Gain reduction: 2-5 dB
Kick Drum
- Ratio – 4:1 to 6:1
- Knee: Hard-knee
- Attack: 2-5ms
- Release: 0.1 to 0.2 s
- Gain reduction: 3-10 dB
Snare Drum
- Ratio – 4:1 to 6:1
- Knee: Hard-knee
- Attack: 1-5ms
- Release: 0.1 to 0.3 s
- Gain reduction: 3-10 dB
Tom Drums
- Ratio – 3:1 to 5:1
- Knee: Hard-knee
- Attack: 5-20ms
- Release: 0.2 to 0.5 s
- Gain reduction: 4-6 dB
Hi-hat
- No real need to compress
Drum overheads
- Ratio – 2:1 to 4:1
- Knee: Soft-knee
- Attack: 1-5ms
- Release: 0.2 to 0.5 s
- Gain reduction: 1-4 dB
I’d advise you to give these a try and see what results you come up with. But remember, there are no set rules when it comes to audio compression in your mixes. Play around and see what works.
Final Thoughts
Modern recording studios and the songs they produce wouldn’t sound the way they do if it wasn’t for the compressor. Because it’s such an important tool, I think it’s worth spending time in getting to know how compression works and what each setting can do to affect and change a vocal or instrumental recording.
How well you use audio compression can make or break the quality of your recordings and your productions.
