Understanding serial compression: how to use it to control dynamic range

Ever sit there slamming your vocals through one compressor and wondering why it doesn’t sound slick, sophisticated, polished, or professional? Now of course, I’m not sitting over your shoulder, watching your moves in real-time, so I can’t rightly say why it doesn’t sound good. But I can tell you this: sometimes one compressor won’t cut it. Sometimes you need several, one right after the other – what we call “serial” compression. 

This article explores how to use serial compression, essential serial compression tips, and provides you with an arsenal of plugins that can help with serial compression in your mix. 

Follow along with  Neutron 4 , an intuitive mixing plugin with powerful dynamics processing.

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You can also explore Plugin Alliance compressors including the Purple Audio MC77, Neold UA2, and more.

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What is serial compression?

At its core, serial compression involves the sequential application of multiple compressors to a sound source. It’s not like parallel compression, where you blend a compressed signal with a dry copy of the sound. No, here you’re stacking compressor after compressor to achieve your sound. Often two are enough to get the job done. Sometimes it’s more than that. 

However many compressors you opt to use, the trick lies in making sure you don’t overdo it. You’re taking advantage of each compressor’s behavior and each compressor’s innate character, combining disparate elements into a cohesive and gelled whole. This should result in a more nuanced control over the dynamics – a guiding hand that feels assured, yet musical. 

A classic example of a serial compressor in action

There’s a combination every engineer should have up their sleeve: some sort of 1176 feeding into some sort of LA2A on a vocal.

Here’s a vocal without any processing, followed by an example with the Purple Audio MC77 (a 76 emulation) feeding the Neold UA2:

These two compressors go together like peanut butter and jelly, or whatever version of that you’re not allergic to. This has to do both with behavior and color. 

The 1176-style compressor works quickly, taming the peaks: you’re using a higher ratio than you’d think here, as well as a fast attack and a medium-fast release. You’re using the input and output knobs to achieve a good swing of reduction on the parts of the vocal that pop out too much.

The optical compressor, on the other hand, is a slower beast: it has a much smoother attack and a more complicated release stage. It reacts musically to the swing of the vocal’s dynamic:

Yes the real magic happens when you use both together, as this video shows:

1176 goes first, optical goes second, and each has a hand in doing something special: the grabby FET compressor snaps fast to get those unruly peaks, so the optical can work less hard, and smooth out the macro dynamics.

So yes – different settings target different things in this vocal example. But you could make this sort of behavior work with any two clean compressors. That would be missing the point: we don’t just use off-the-shelf plugins to make this classic trick work. We use the special grabby, grimy magic of the 76 combined with the flowing richness of the 2A. The two complement each other.

How to use serial compression in a mix

First let me say that there is no one way to use serial compression in a mix. All we can do is teach you to look out for instances in which serial compression might help you. So, with that in mind, here are a few situations to keep at the forefront of your mind.

1. Important, unpredictable tracks with lots of dynamic range

Vocals, bass, and drums: what do these instruments have in common? One, they are vital to most arrangements. Two, the dynamics of these instruments can vary greatly (depending on the player of course). 

Because of this, serial compression comes in handy when dealing with these instruments – or indeed, any instrument that is both dynamic and important to your arrangement. 

Often you use one compressor with a faster attack and release to tame the peaks, and the other one to smoothen out longer phrases (just like the classic 76/2A example). 

You can also accomplish the same effect with two clean compressors, however, such as two instances of Neutron’s compressor module with different settings. 

While vocals, bass, and drums are the instruments I’m calling out by name, they are hardly the only ones to look out for. Consider a jazz mix in which the trumpet takes an extended solo: we don’t want to mess with the dynamics of the performance too much, as that will alter the musical intent. However, we don’t want to lose the instrument to the noise-floor of the  surrounding rhythm section, or blow out our eardrums with its loudest notes. Here a clean serial compression approach could work wonders. 

2. Tracks that almost groove but need help

In mixing, we’re frequently faced with an insidious problem: performances that nearly groove, but need a little help from us to really bounce and swing. 

In these situations, a particular kind of serial compression can help. On the first compressor, you use attack and release controls to better stabilize the track to the groove of the music. Usually, medium speeds work well here, or time-constants set to the tempo of the music.

Observe this guitar part, which feels perfectly fine when heard against the bass and drums. 

We’ll add the first compressor, the bx_townhouse buss compressor: 

This VCA compressor, honed in a sort of SSL style, is doing a good job of getting the guitar groove closer to the drums. 

Now comes the second compressor, which we’re using with an external sidechain input. We are using the snare to trigger compression on the guitar. This results in the guitar naturally cresting and bouncing with the drum beat: 

3. Tracks that require color, but not obvious distortion

Stacking compressors in a serial arrangement is a quick way to get yourself to flavor town. 

Observe our little practice mix again, this time with the bass pushed way up. Let’s pick two compressors from Plugin Alliance and run them in series. 

In this example, neither of them is compressing all that much, but you can hear more weight, roundness, and color. This color has been implemented with subtlety. If we had used a harmonic saturation processor, we’d have a lot more grit on the sound. 

The trick with color compression is to know your compressors intimately. Take the time to practice with your tools, so that you understand the interplay between compressors in your arsenal.

Techniques that are “serial compression” adjacent 

Believe it or not, you’ve probably used a few serial-compression techniques without realizing it. Let’s cover a few common ones below.

De-essing and compressing

De-essers can be thought of as compressors with highly-specialized controls. Full-band de-essers are basically compressors with the sidechain automatically tuned to sibilant frequencies. Split-band de-essers are essentially multiband compressors with a single crossover point. One band is effectively bypassed, while the other clamps down on sibilance when receiving its orders from the sidechain detector circuit.

Either way, if you’re using a de-esser followed by a compressor – or the other way around_you’re already taking advantage of serial compression.

Dynamic EQ before the compressor

Similar to how we use de-essers, we often use some dynamic process to work on a vocal’s midrange resonance before hitting a compressor. This could be a dynamic EQ, like the kind found in Neutron, or spectral processors like the Sculptor in Neutron or the Stabilizer in Ozone. Either way, if you’re using these tools in conjunction with a conventional compressor, that’s serial compression.

Parallel compression in series

A riddle for you:

When is a parallel compressor just a serial compressor in disguise? When you’re using parallel compression after an initial round of dynamics processing – or before feeding a compressed submix.

Say I’ve got a drum sound, and I’m using an SSL-style channel strip compressor on the kicks, snares, and triggers. Say, furthermore, that I’m now routing these shells to a parallel aux, where I’m using a DBX-style compressor to give these drums more cut. 

This, my friend, is serialized parallel compression, and you can use it to great effect.

Furthermore, if your drum submix bus has compression on it – and your parallel compressors are feeding this bus  – that’s yet another round of serial compression.

Start using serial compression

Serial compression, with its layered approach, requires a deep understanding of the tools of your trade. Armed with insights into what serial compression is, how to wield it effectively, and the plugins that amplify its capabilities, you’ll be able to use serial compression effectively for nuanced, dynamic control.

And remember, don't shy away from experimentation! The examples we walked through above serve as guidelines, but they’re not the complete answer for what you can do in your productions.

Demo Neutron for free to start experimenting with serial compression in your mix. 

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