In the world of mixing and music production, multiband compression is a powerful tool and undoubtedly one to know.
Some might consider it essential, but it is still a technique that can be a bit difficult for beginners to grasp, because unlike traditional compression that affects the entire sound spectrum, multiband compression allows for independent processing of different frequency bands.
So it allows for more precision, but it also adds complexity.
Already, classic compression is hard to hear/understand… so if now we compress frequencies differently…!
Note: If you are not yet comfortable with compression, know that I offer on Projet Home Studio a course that will explain everything you need to know about the subject and thus greatly improve your mixes.
👉 If you’re interested, click here to discover the training.
That said, even though multiband compression is indeed a fairly advanced tool in concept, and should be used more sparingly than sometimes suggested, it remains a truly useful technique that can literally save your mix — and in any case, it will give a boost to your music productions.
With this article, I have tried to simplify the subject as much as possible to make it as clear as possible for you.
We will indeed see:
- What multiband compression is;
- In what situations it is used;
- A concrete example of using multiband compression;
- And some plugin suggestions (to have the right tools from the start)
What is multiband compression? (definition)
Before discussing possible applications, it is important to understand what a multiband compressor is.
Classic compression
Classic compression, sometimes referred to as “wideband compression”, is an audio processing technique used to control the dynamics of a sound signal.
By reducing the gap between the quietest and loudest sound levels, it helps make a recording more coherent and homogeneous.
The compressor works by reducing the gain of the audio signal when it exceeds a predefined threshold, according to a determined ratio.
By mastering these settings, you can for example soften excessive volume peaks, add density to a recording, or create cohesion in a mix so that the instruments sound like they are all playing together (this is what we call sonic glue).
However, classic compression affects the entire frequency spectrum uniformly, which can sometimes lead to undesirable compromises in sound quality.
► Feel free to read my complete guide on compression if needed
Multiband compression
This is where multiband compression comes in, an advanced audio processing technique used for both mixing and mastering.
The idea is to divide the sound signal into several distinct frequency bands, each of which can be compressed independently.
Unlike classic compression, which affects the entire sound spectrum uniformly, multiband compression allows for more precise and targeted control: by separating frequencies into different bands, it enables specific processing of lows, mids, and highs, applying compression settings tailored to each band.
But what’s the point?
But what’s the point for mixing or mastering?
Well, to illustrate this, let’s take a small theoretical example.
Imagine you have a bass track that has a particular resonance, but only at certain moments: for example, on specific notes, bam, you have a resonance that stands out.
If you use an equalizer to tame this resonance, your equalization will apply constantly: you will thus cut certain frequencies even when the resonance is not present.
If, on the other hand, you take a multiband compressor, you will be able to basically set it by saying, “if ever, on this specific frequency band, you have too much sound energy, well, you will compress it to calm the resonance.”
This is something impossible to do with a standard compressor, which would affect the entire frequency spectrum indiscriminately…
Settings of Multiband Compressors.
In terms of settings, the only thing that really differs on multiband compressors is what is called the cutoff frequency or crossover.
Everything else is similar to what you find on classic compressors (have you read my article on compressor settings?).
Let’s do a quick reminder:
Cutoff Frequencies (Crossovers)
Cutoff frequencies determine the points where the audio signal is divided into different frequency bands.
Choosing these frequencies well is important to properly isolate the areas of the sound spectrum you want to process.
For example, one might think that in a mastering context, a bass band could cover from 20 Hz to 250 Hz, while a mid band could go from 250 Hz to 4 kHz, and a high band beyond 4 kHz.
But these numbers don’t really make sense: it all depends on what you want to compress and why…
Threshold
The threshold is the level at which compression begins to apply. A lower threshold will apply compression at lower signal levels, while a higher threshold will only target peaks.
Ratio
The ratio determines the amount of compression applied once the signal exceeds the threshold. The higher the ratio, the more aggressive the compression.
Attack
The attack defines how quickly the compression starts after the signal exceeds the threshold.
Release
The Release determines how quickly the compression stops once the signal goes back below the predefined threshold.
Make-up Gain
After compression, an output gain or make-up gain can be used to compensate for the gain reduction applied by the compressor.
Each band may require a different gain adjustment to maintain an overall balance of the mix.
Applications of Multiband Compression
Well, you might say, OK, multiband compression allows for selective compression of a frequency band, but concretely, what can we do with it?
And I agree with you: knowing the tool is good, but it’s even better to know what it can be used for! 🙂
So let’s take the time to zoom in a bit on the uses.
The Basic Idea
In any case, the idea of this type of compression will be to compress very specific frequency bands.
This means that when you have a problem that is not global in terms of frequencies, but occurs dynamically and over a given frequency range — then it’s probably a good time to use multiband compression.
Possible Applications
This means that already, from the moment you have a resonance at a specific frequency and it is punctual (= it appears and disappears), then you can try using a multiband compressor to control it.
Even without talking about resonances, from the moment you have something that stands out too much at times over a frequency band, then use a multiband compressor.
Here are some examples:
- Control of highs to avoid harsh sounds on a voice;
- Control of highs to calm aggressive transients from cymbals or snare drums that cut too much in the mix;
- Reduction of unwanted resonances in low and mid frequencies on vocals or bass;
- Stabilization of attacks on guitar or bass strings without losing depth in low frequencies;
We can also imagine situations where we are not necessarily looking to calm a strong problem, but where we want to level a track or a mix over certain frequencies.
Just like when leveling a voice with a LA2A compressor to keep the sound level consistent throughout the piece, we may indeed want to:
- Level the lows of an instrument to achieve a dense and coherent sound;
- Balance the frequencies of a specific instrument, such as the guitar or piano;
- Gain density and heaviness on an electronic beat;
- Gain density / cohesion in the lows or highs during mastering;
- Precisely control the dynamics of several frequency bands to homogenize level variations during mastering.
And if we go even further, a number of compressors can work in sidechain mode: you can make it so that, for example, a bass line ducks every time the kick hits… but affecting only the low frequencies, so that it is more subtle than a classic wideband compressor.
(if you make electronic music in particular, this is a technique I detail in my training on mixing Kick & Bass).
In short, you see, overall, it gives us quite a few possible uses: we are on something a bit similar to compression, but which is at the same time more precise and allows us to solve very specific problems.
A concrete example of using multiband compression
Let’s take a concrete example with the following audio track:
It’s a short and really simple bass line, but if you pay attention, on the attack of the notes, there is an unpleasant resonance around 350 Hz that sounds like this:
But the resonance only occurs on the attack of the notes, not too much on the sustain.
So, not all the time.
(I’ll let you listen to the audio examples above if needed)
This is where our multiband compressor will come in handy: we will try to compress a frequency band centered around 350 Hz to calm the resonance by compressing these frequencies only when there is too much energy at that point.
Here is the result:
And here are the settings I made on my compressor:
As you can see, the resonance hasn’t completely disappeared: we might need to go further with an ultra-targeted EQ or a new multiband compressor.
However, we have largely calmed it down and it will typically stand out less in the mix: before multiband compression, the resonance was very pronounced, whereas after multiband compression it integrates better with the rest of the sound.
And all this, without strongly impacting the recording: we only compressed the resonance when it was too present — and that’s it.
Some suggestions for multiband compressors…
To conclude this article, here are some suggestions for multiband compression plugins.
Because while there are different choices on the market, some are definitely more effective than others.
(by the way, feel free to also check out my recommendations for free multiband compressors)
1. FabFilter Pro-MB
The first plugin I would recommend is the famous Pro-MB from the equally famous Dutch brand FabFilter.
In terms of sound, it is really super effective — no problems on that side: you can compress your signal quite heavily while maintaining a transparent quality.
However, the main strength of this plugin, like most effects from FabFilter, is the workflow: the interface is very clear, easily manipulable, the settings are immediately accessible…
…in short, you can focus on the sound rather than fighting with options that are difficult to understand or manipulate.
Notably, there is the possibility to specifically listen to a frequency band, which is very handy when you are adjusting your multiband compressor.
► Click here to see the current price of the plugin
2. Tokyo Dawn Records Nova
Another very interesting option from TDR: the Nova plugin.
This time, the plugin is completely free, although there is a more comprehensive paid version.
But despite that, it remains a perfectly usable tool in a professional context.
This tool is not just a powerful multiband compressor, as it also offers interesting equalization features — which you can easily combine with compression.
Overall, I see this plugin as an alternative to Fabfilter’s Pro-MB: overall we have similar sound performance, but some features are a bit more difficult to manipulate.
► Click here to download the plugin
3. Xfer Records OTT
If you make electronic music, I recommend checking out the OTT plugin from XFer Records.
This one is a bit special, because it replicates the behavior of one of the presets from the multiband compressor built into the Ableton Live DAW.
In fact, while it only has three bands, OTT goes further than a classic multiband compressor as it offers both traditional compression and a form of compression known as “upward” which reduces the dynamic range of the audio signal from the bottom (by amplifying the quieter sounds).
Ideal for gaining loudness/density in a techno or house mix, for example.
► Click here to download the plugin
4. Lindell Audio 354E
At Plugin Alliance, you will find this plugin which is not very well known but that I had tested some time ago in the pages of Projet Home Studio.
In fact, compared to, for example, a FabFilter Pro-MB, the Lindell Audio 354E is much more colored in terms of harmonics, frequency response, and compressor attitude.
Sure, we only have three processing bands, but that’s already a lot and it allows you to easily adjust the dynamic behavior of all kinds of tracks. For example, I really like this compressor for adding punch to my drum groups! But it is also usable in a mastering context!
In short, a plugin that does a lot of things but with a unique “analog” attitude!
► Click here to see the current price of the plugin
In conclusion
There you go, you now have all the information to understand multiband compression.
That said, we know that compression is something that takes time to master.