A compressor is an audio mixing effect that affects the dynamic range of audio playback. Dynamic range is the difference between the loudest and the quietest parts of your audio. Compressors help balance out this volume difference for a more leveled-out mix.
Recommended Reads: EQ 8 Equalizer, Normalizing, and Quantizing in Ableton
There are different classifications of compressors with different types of in-built circuitry, that not only control dynamics but also color the audio. While some are faster and transparent, others are slower and gentler, suitable for gluing different audio inputs.
Recommended Read: Parallel Compression in Ableton
Ableton comes with three types of compressors (Compressor, Multiband Dynamics and Glue Compressor). For this demonstration, I shall be using Ableton’s primary compressor, which is transparent and an excellent all-around compressor.
Loading a Compressor
This section will show you how to load Ableton’s compressor onto your track (audio/MIDI/return)
Step 1: Create the type of track you want to effect under Create options
Step 2: go to Audio Effects in Ableton’s browser, and open the Dynamics dropdown menu to find the compressor
Step 3: double-click on the compressor plug-in to open it on your selected track, or drag and drop it into your track
Note! Compressors are audio effects, and therefore need an audio input source to work. If you load any audio effect plug-in into an empty MIDI track, Ableton will ask you to load an instrument into it.
Tip! Ableton provides different presets for different compressors, and it is very easy to find them. Let me demonstrate
Step 1: Go to your preferred compressor and select the dropdown menu expander
These presets have their use cases. I use the Precise preset because it suits my productions when I sidechain kicks into tracks to create room for the kick to pop through the mix, or create a bounce effect to pads and synths.
Now let’s have a look at the specific parameters and features of Ableton’s compressor, and what they do:
The general parameters are the main parameters on the compressor GUI when you load it into your track initially
The left panel includes the universal compressor controls found in nearly every compressor in the world. This is what they do:
Ratio: This controls how much the incoming audio is reduced by the compressor. The higher the ratio, the more the signal is compressed. It is measured in decibel (dB) ratios. For example, a ratio of 4:1 means for every 4dB of signal that goes above the threshold, the gain will be taken down to 1 dB (of signal gain) above the threshold. This means that the signal gain will be reduced by 3 dB.
Attack: this parameter controls how fast the compressor squashes the sound. A fast attack catches the transients of an audio signal. This may not be ideal for percussive instruments as it may ‘blunt’ the impact of the signal, but may be ideal for catching extremely harsh transients.
Release: this parameter controls how fast or slow the compressor stops processing your audio. Depending on the average length of your audio signal, adjust this parameter to fit the general length. If your signal has varying lengths, Ableton has an ‘auto’ release function that makes your release adaptive to the audio input.
This panel visualizes what the compressor is doing to your signal. You can set the threshold for your audio input that will trigger the compressor to begin processing. You will see the total gain reduction of your audio signal. The output level slider shows the volume output and you can slide this parameter up or down to compensate for the loss of volume post processing.
At the bottom of this panel, you can switch between the different views of the compressor visualizer.
In the bottom panel, you can also control the knee and look-ahead parameters.
Similar to an attack, the knee parameter controls the speed at which the compressor processes your signal. It also controls how fast your compressor reaches the threshold
The Look ahead enables the compressor to analyze your signal and predict how it gets processed. In return, this is what increases your compressor’s accuracy.
The right panel helps control your overall compressor behavior.
Makeup: this enables your visualizer to show you the post compression makeup gain.
RMS: ‘Root Mean Square’ uses the mean of the average between the quietest and loudest parts of your signal, concerning your threshold, to process your audio. It is more gentle compared to the ’peak’ option
Peak: this parameter when activated, will make the compressor only focus on the peaks of your signal that go above the threshold.
Expand: This is a lesser-known function, but what it does is, the opposite of gain reduction. Instead of bringing its peaks going above the threshold, it raises parts of the audio signal that are playing below the threshold
Dry/Wet: This parameter controls the blend between the signal before and after processing.
This feature can be accessed when you open the expanded controls menu. Here is where you will find the sidechain options.
When the sidechain is activated, you will need to set the input channel, and choose where you want the input to come in before/after the effects are loaded into the rack or the mixer (return and volume fader controls)
You can also control the volume of the input signal and the mix between the dry input signal, and the signal post effects.
Once EQ is activated, you can to control which frequencies will cause the ducking effect when the compressor is loaded. There are different bell curves that affect the behavioral relationship between the two signals. They have different parameters, but you will generally find that the parameters are: frequency, which allows you to choose what frequency is being used to sidechain, gain, which controls the loudness and audibility of these frequencies, and in some instances, Q, which controls the wideness of your frequency band.
You can also listen to what the input sounds like in the processed audio and make fine adjustments to the sidechain effect.
Pro tip! The more you work with this compressor, you will find use cases and parameters that you can use throughout your production. Instead of having to load up your compressor and adjust to the same parameters every time, you can save your settings as a preset. This is how you do it:
Step 1: Select the floppy disc icon on the top right corner of the Compressor
Step 2: this will be saved under the user library folder under presets – compressor as a .adv file
You can now use this preset whenever you need it. This step can be repeated for any audio effect in Ableton.
Compressors are an essential part of audio mixing. They help balance your audio and bring up the best in them if you learn how to use them properly. This tutorial should get you started with how to load and the parameters that control Ableton’s compressor. With this tutorial, you should have a basic understanding of the compressor plug-in and the different use cases. I shall provide further breakdowns on the different compressor plug-ins and parameters in future articles, so stay posted. Use this plug-in correctively and creatively, and most of all, have fun!