Dynamics processing explained
In last week’s post, we talked about the interface of our new module Librae Legio and how it works.
Today we’re taking a deeper dive into the types of processing used in Librae.
Broadly, dynamics processors automatically change the levels of sounds based on thresholds. They come in a variety of forms and have a near-infinite number of applications in mixing, mastering, and even sound design. Whether you want to make a small adjustment that helps an individual sound fit into a patch, or you need to apply master-bus processing that changes the dynamics of a whole track, dynamics processors are helpful tools to have in your arsenal.
Effects are often broken out into individual units / plugins / whathaveyou, but we think of a lot of processing along a spectrum: at one end, we have sounds that are too quiet that we want to make louder; at the other end we have sounds that are too loud that we want to make quieter. As with most things, there is nuance to be applied to your mix, especially at the extremes of the spectrum.
Let’s start with compression and expansion.
What is compression?
Compression is, by far, the most common type of dynamics processing. It’s also somewhat misunderstood. In its simplest form, compression reduces the dynamic range of a sound by turning loud things down (and effectively quiet things seem louder as a result). The controls on a compressor allow you to change how much things are turned down once they pass threshold, and how quickly.
You may have heard that compressors make things louder, but this isn’t quite the case. After using a compressor turns things down, your song/track/etc., will have a lower average volume, so most compressors add in a makeup gain stage to compensate for this. This is not part of compression per se, just another control that most compressors have.
Let’s look at a real-life example of compression using Librae Legio: here’s a simple synthetic drum pattern with a kick and snare. We’re using reasonably gentle compression from Librae to bring out the transients (fancy talk for the impact part of a drum sound. Transients are loud.). The compressor lets the transient through, and then turns on and brings down the dynamics of the tail of the drums, creating a more impactful drum sound.
What is expansion?
Expansion is kind of like the opposite of compression: instead of turning down loud sounds to decrease dynamic range, it turns down quiet sounds to increase dynamic range. This can be a nice way to liven up an instrument if it needs more energy, and is generally most effective when used subtly (although it has its uses in the extremes, too, which we’ll talk about below).
Expanders allow you to change how much things are turned up once they pass a threshold, and how quickly. Because louder sounds hit the threshold more easily than quieter sounds will (depending on where it is set), quiet sounds get quieter, louder sounds get louder. I mentioned that this is a spectrum: while it’s an oversimplification to say that they are equal and opposite, it’s a nice way to start to wrap your brain around how these things work if you’re new to dynamics processing.
Let’s listen to Librae Legio do some expansion. Here, we have a relatively static bass part that could be a little bit more interesting. By running it through Librae’s expander, we can increase its dynamic range just enough to make it more interesting.
Processing at the extreme ends of the spectrum
Compression and expansion are nice tools for putting a mix together. Generally we want them to be subtle and transparent in a mix: we don’t want it super obvious that there is compression happening… except for when we do want that! We can crank up our compressor or crank up the expander for the extremes. If we go really far out on this spectrum we’ve created, then we have new names for the techniques: limiting and noise gating.
Extreme compression: What is limiting?
At the extreme end of compression is limiting. We used compression earlier to shape the dynamics of a sound and create more impact, but limiting is more drastic: if sound goes above a certain level, it’s turned down enough to keep it below a set dB level, creating a hard limit on the maximum level of audio run through it.
Limiters can be used to keep an individual instrument (or set of instruments) within a certain dynamic range, or, most famously, on the master bus to make a full mix as loud as possible by reducing its dynamic range to an extreme and then bringing the overall level up.
In this example, we’ve run the same drum loop as before through Librae Legio’s limiter.
Extreme expansion: What is a noise gate?
Just like extreme compressors have their own somewhat unique functionality, extreme expansion can be useful too. Recall that an expander makes the quieter parts even more quiet? At the extremes, you can use this to completely silence the quiet parts of a signal. You might want to do this when you have noise in your signal chain (which is virtually unavoidable!). This is called a noise gate. Noise gating can be quite noticeable, but when used sparingly it can be a great solution to an otherwise annoying problem. Here, we have a minimal synth part recorded with a particularly noisy signal chain – by carefully using Librae Legio’s noise gate, we can remove a majority of the noise, cleaning up the signal.
Processing with Librae Legio
It’s quite common for dynamics processors of all types to have a huge number of parameters – especially digital units and those used in software. For example, compressors often have controls for attack time, release time, ratio, threshold, and makeup gain at minimum. While being able to tweak every parameter can be useful in some contexts, we like our modules to be immediate and jammable. If you’re interested in dynamics processing but don’t want an overwhelming number of parameters to tweak, Librae Legio has just five controls and still offers all the dynamics processing options we’ve talked about in this article, as well as two types of saturation, all in 6 HP.