Music Producers: Why Compress? And When Not To

To compress or not to compress? Well, it depends…

Alongside equalisation, compression is one of the most essential tools available to anyone working in audio. Whether you’re an audiobook or podcast producer, a video game or movie sound designer, music producer or mixing engineer – almost everyone who works with audio will reach for a compressor at some point during their week.

But what exactly does a compressor do?

The most traditional use for an audio compressor is to reduce dynamic range in a recording. Compressors achieve this by reducing the volume of audio by a set ratio whenever the signal crosses a certain volume threshold. This decreases the loudest parts of an audio file while leaving the quieter parts untouched, making the entire clip more consistent in volume.

Compression is useful for a number of reasons. As discussed in our article on the Top Compressor Plugins, compressors can be used to control levels, emphasise elements, add cohesion to a mix, or in a number of creative ways – you may be familiar with sidechain compression which is often used in electronic music to create a rhythmic pumping effect..

However, despite their ubiquity, compressors are not always the best solution in every scenario. In some cases, excessive compression can rob a mix of its natural dynamics and liveliness. So, let’s explore why you should use compressors – and when you might be better off without them.

 

We compress for dynamic range

The most common use case for a compressor is to control the dynamic range of an audio signal.

The dynamic range of a sound recording refers to the difference between its quietest point and its loudest point. The best way to measure it is to use a metering plugin like Full Metering by IK Multimedia or SSL Meter by Solid State Logic.

//Image: Full Metering

You’ve read how a compressor reduces the dynamic range of a recording by reducing the gain or an audio file when it crosses a certain threshold. One of the most common examples of this is when working with vocal recordings. 99% of the time, the lead vocal serves as the focal point of the track, requiring clarity and consistency so it isn’t overshadowed by other elements.

However, no singer delivers a perfectly even performance. In fact, you probably wouldn’t want them to. The natural volume fluctuations in a performance provide much of the expression that’s so important to a great song.

By using a compressor, you can reduce the dynamic range of vocal recordings, while maintaining all of that raw motion, helping it stand out in the mix, and keeping the listener’s attention.

It’s common practice to compress vocals in pop, rock and hip hop. However, in some contexts you may want to maintain the original dynamic range of a recording.

Take, for instance, choral recordings. If you’ve ever popped on some carols at Christmas, you may have found yourself cranking the volume on your sound system to the max to make out the opening notes of a song, before being deafened as the piece crescendos later on.

In these more traditional settings, producers and mix engineers prioritise maintaining the natural acoustics of the space where performances were recorded over reducing the dynamic range, preserving the natural rise and fall of a live choral performance.

 

We compress for loudness

One significant advantage of reducing dynamic range is that it allows for greater perceived loudness.

That may seem counterintuitive – how can reducing the volume of the peaks of a recording make it louder?

By taming the loudest transients, compression enables engineers to increase the overall gain of a track without causing distortion or clipping. This makes the quietest elements more audible while keeping peaks under control, resulting in a track that sounds fuller and much louder.

 

We compress for character

Beyond being a mix tool, compressors can be used creatively to add character to recordings.

An obvious example here is the “radio voice” sound. Listen to a popular drive-time talk show on the radio, and you‘ll notice all the voices have a distinctive, powerful sound to them. This is a result of heavy compression, and it helps presenters sound exciting and authoritative.

This kind of heavy compression can also define an artist’s sound. Take Julian Casablancas of the Strokes as a prime example. When recording The Strokes' debut album Is This It, Casablancas famously said he wanted his voice to sound like your “favourite pair of blue jeans” – warm, worn-in, and slightly gritty. This sound was achieved through a combination of EQ, distortion, and heavy compression.

However, it’s important to recognise that different vocalists require different treatments. What works for one artist may not suit another, and over-compressing can sometimes strip a vocal of its natural dynamics and texture. It’s important, as a producer or mix engineer, to be able to make the right decisions for the recording you have in front of you.

 

Samples might not need to be compressed

When working with your own audio recordings, compression is often necessary to help balance dynamics. However, if you’re using pre-recorded samples from a library like Loopcloud, you may not need to compress at all.

//Image: Loopcloud VST

Sample pack creators are often experienced producers and mix engineers, and they’ll want their samples to sound loud and punchy so you can just drop them straight into your project.

To achieve this, they’ll optimise their sounds for immediate use, compressing and processing them to give them a professional sound.

That said, there are many cases where you will still need to use a compressor when working with samples.

Though you can just drag and drop samples into your project, it’s often more interesting – and more fun – to manipulate your sounds by cutting them up and using effects. Messing with the samples to make them your own can alter dynamics, and a compressor can be useful to bring things back under control.

Additionally, even when compression isn’t needed for balance, it can still be used creatively, for example, by adding sustain to drum hits or giving basslines extra weight.

 

We use compressors to glue a mix together

Compressors aren’t just used on individual elements in a mix, one of their most common uses is to “glue” multiple parts in a track together

What do we mean by glue? Essentially, it’s the bringing together of separate elements so that they sound like one cohesive end product. Compressors can achieve this by applying the same dynamic processing to multiple elements.

For example, say you added a compressor to a drum buss, where your loudest drum element is the kick. Every time the kick plays, it will trigger the compressor, altering the dynamics of not just the kick drum, but also any other drum element that plays simultaneously – this could be a snare or hi hat, for example.

//image: SSL G-Master Buss Compressor

On a larger scale, compressors are often used for glue on the master buss of a project, and you can get dedicated compressors for just this purpose. Modelled on the original hardware SSL console compressor, Solid State Logic’s SSL G-Master Buss Compressor is perhaps the most famous software example of a master buss compressor.

Though many producers employ compressors as a means to glue mixes together, some legends of the game avoid using them entirely.

One of the most famous examples of this is Bruce Swedien’s work on Michael Jackson’s smash hit album Thriller.

Though Swedien did occasionally use two Universal Audio LA2As – Swedien used hardware compressors, but the Teletronix LA-2A Leveler Collection would help you achieve the same sound – on individual tracks in his mixes, he would never use them on master busses. Swedien loved transients in his mixes, and took every care he could to maintain their power.

It’s reported that he wouldn’t listen back to his rhythm section recordings until it was time for the final mix. This meant the tapes didn’t get played over and over, causing them to lose their punch.

This love for transients was also why he chose not to compress his master busses. Instead, Swedien controlled the dynamic range of songs on Thriller through automation, and meticulous fader riding. It sounds like a lot of work, but this painstaking approach did produce one of the biggest-selling albums of all time, so there’s probably some truth there.