A compressor is an important tool when it comes to mastering. Today we’ll go through some tips to get the most out of it.
First: What is a compressor?
A compressor, in short, is a device which reduces the dynamic range of an audio signal. Dynamic range is the difference in loudness between the loudest and quietest parts of your mix or any kind of audio source. A compressor reduces the volume of the peaks or louder parts of a mix (for example when a kick drum hits). As a result, you get a more „flat” audio curve. The dynamic range decreased. The volume can be brought up with a makeup gain knob or manually by increasing the output level. You left with the same peak level but the overall loudness increased.
How much compression and what settings should I use?
This depends very much on the mix and musical style. In some genres it’s not necessary to use compression at all, in some it’s a crucial element of the sound. If you end up using a compressor on the master, always stick to low ratios (from 1.5:1 up to 3:1 - slight to hard compression) and low Threshold settings. Always aim at keeping the gain reduction to not more than 3-5dB.
I like to find the Threshold and Ratio first. Check the RMS values to understand how much gain reduction you need. Once you have the right loudness, tweak the Attack and Release to get the right movement of the effect.
Should I use a multiband compressor?
Yes. A multiband compressor splits the signal into multiple frequency sections (for example one for the bass, one for the mids, one for the highs). As compressors react differently to different frequencies because of their different wavelengths and amplitude, controlling each band separately gives you the most control over the dynamics.
Be careful though. For a multi-band to work, a plugin needs to use crossover filters to separate your audio into different bands. Anytime you run audio through a filter, you lose a little bit of fidelity. That results in a little bit of ringing, noise and distortion. You want to be careful when using a multiband compressor and remember not to over process - as that can easily mess with the phase of your master and cause it to lose fidelity.
Finding the perfect attack & release
Very short attack times will inevitably result in a reduction in the track's punch. Turn the attack too long and the compressor starts to lag behind as if it can't keep up resulting in unwanted, unrhythmical pumping. Bear in mind that it may be after you've experimented with the release before you find the perfect attack.
Too short release times and you will hear the compressor aggressively jump back at you after every transient impact. Too long release times and you will feel the lagging behind effect again, along with a huge amount of attenuation. The real sweet spot is where the release begins to compliment the attack and the BPM of the track.
Good luck with your mixing and mastering. See you in the next articles!
I’m a music maker who likes to share his experiences with other producers. I’m regularly going to show up with music and content at PML.
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