Compressors are an integral part of the mixing process.
Without this tool, your mix will be dynamically unbalanced and stand little to no chance of being labeled a professional mix. To many producers, it can be very difficult to understand how compressors work and how they can be applied to their productions in a positive way.
In this article, I am going to go over what compression is, the basic controls of a compressor, and how to use a compressor in your music.
What is a compressor?
Before we dive into the controls and techniques of using a compressor, you must first understand what a compressor actually is.
A compressor is an audio processing device that reduces the volume of loud sounds and amplifies the quieter ones, thus reducing or compressing your audio signals dynamic range.
In simpler terms, a compressor is an automatic volume fader.
Imagine you have your hand on a volume fader. When the signal gets too loud, you move the fader down. When the signal is too quiet, you push up the fader. Essentially, this is what a compressor is doing.
4 main parameters
Now that we have a clear understanding of what a compressor actually does, we can go over the four basic parameters of a compressor.
The first main parameter we are going to go over is the threshold.
The threshold control sets the level at which the actual compression starts compressing. A lower threshold will compress more of the audio signal and a higher threshold will compress a smaller portion of the audio.
The next main parameter is the ratio.
The ratio is the strength of the compressor. It sets how much compression is applied. A 1:1 ratio on your compressor means that no compression is being applied. A 4:1 ratio means that every 4 dB over the threshold, the signal will be reduced by 2 dB. You can think of the threshold and ratio as the muscle behind the compressor.
Next, we have the attack control.
The attack will signal to the compressor how quickly it should start to compress your audio. A short attack, will engage the compressor very soon after or immediately after the signal passes over the threshold. A short attack is considered to be from 0 milliseconds to 15 milliseconds. A longer attack will allow more of the audio signal that passes over the threshold to go through the compressor without it being compressed. A longer attack is considered to be from 15 milliseconds to 150 milliseconds.
The last main parameter on a compressor is the release.
The release is how fast the compressor stops compressing after the signal goes back below the threshold. A short release will tell the compressor to immediately loosen its grip on the audio and stop compressing. A short release is from 0 to 40 milliseconds. A longer release will tell the compressor to gradually release its grip on the audio. A long release is from 40 to 250 milliseconds.
On your compressors, you might notice a few other parameters that were not covered here. There are more controls on a compressor than just the four mentioned above. This list just goes over the most important controls that will be on every compressor.
Applying a compressor to your music
Now that you have a solid understanding of what compression is and its four main parameters, we start to apply the compressor to our sounds. The most common use of a compressor is to balance out the inconsistent volumes of your individual sounds.
Having different elements in your mix that continually rise and dip in volume will create an unbalanced and confusing mix.
To fix the inconsistent volumes in our sounds, you will want to have a quick attack (0-15 ms) and a (100-150 ms) long release. You want the compressor to start acting immediately, and having a quick attack engages the compressor as soon as the audio goes over the threshold. We will use a long release so the compressor doesn’t cause anymore imbalances. If the compressor is reducing the audio and it all of a sudden stops, then the audio will go from quiet to loud very quickly. Having this long release allows the compressor to slowly stop compressing.
The ratio and threshold will need to be set according to the specific audio you are working with. Again, the goal here is to make sure that the volume levels are consistent and sound smooth. So adjust the ratio and threshold accordingly.
Another common use of a compressor is to glue your sounds together. In your tracks, you will have multiple sounds that play at the same time. The combination of all of these sounds often times leads to a little inconsistency in volume levels. Using a compressor on the group of these sounds will allow you to obtain a more steady signal.
To glue your sounds together, we will use a longer attack (20 ms) and a longer release (150 ms). We use a longer attack because again, we don’t want to add anymore volume peaks and valleys.The ratio will be mild in this case. We don’t want the compressor to be too strong here. A ratio of 3:1 will do just fine to glue our sounds together.
Again, the threshold will be dependent on the audio source that you use it on. Just keep in mind that you only want a small amount of compression to glue your sounds together.
Compressors are one of the most fundamental mixing tools. They are required to achieve a dynamically balanced and professional mix. By reading this article, you will understand what a compressor is, its main parameters, and how to apply compression to your track in a professional way.
Daniel is a caffeine-dependent entrepreneur, music producer, sound design junkie, and world traveler crazy about teaching modern electronic music production through his site SoundShock.