How important are compressors for live music

5 areas of application for the compressor

Studio tips: tricks that make the world a better place
by Björn Bojahr,

When I made my first experiences on the live mixer many years ago, there were EQs and effects devices in the rack, but no compressors! I only remember a limiter in the power amplifiers as the only dynamic tool. It was immediately clear to every newcomer what EQs and effects devices would be needed as soon as the first signals were pulled up on the mixer. But compressors? What for?

Today we often come from a different perspective: Every DAW and every digital mixer has at least one compressor per channel, and as soon as I load any channel preset from the factory settings, the thing is guaranteed to be active! But do you really need it?

One of my first compressors was an affordable Behringer compressor many years ago. Without looking at the instructions, the first thing I did was send a few signals into the thing and was, to put it mildly, quite disappointed. The LEDs blinked, but the result did not sound a bit punchy and sometimes seemed to lower exactly the areas that made a good sound a bad one. Terms like "fat" or "assertive" wouldn't even have crossed my mind!

Even after reading the instructions, I wasn't any smarter as a newcomer at the time, because even with the fastest control times, which according to the instructions were really outstanding and which I had of course set, I did not achieve any kind of positive change that gave me an aha left behind ...

However, the fault was not necessarily due to the device, but mainly to the fact that at the time it was not even clear to me what I wanted to achieve with the compressor. This episode of Studio Tips is about a few simple areas of application in which a compressor can really help us, but also about the cases in which incorrect settings might worsen our mix!

Volume jumps due to different recording situations or song sections can be adjusted with a compressor, but this is much more elegant with track automation. The principle is of course particularly suitable for longer recordings, drawing each snare drum individually probably takes too long ...
Automation data using the mouse is not the right solution for every case. If you don't have a DAW controller with motorized faders, check whether you can use a simple MIDI controller, such as the mod wheel on a synthesizer, for programming. With Logic you can find this quick access function in the automation settings.

Different takes

At some point, when the first tracks in your song are there, you will certainly deal with the volume of the individual takes. Some are quieter, others louder - but does a compressor really have to adjust it?

It is important that we bear in mind what a compressor actually does: It cuts the overall signal for a certain time as soon as a certain level is exceeded. In quiet passages, it does not intervene in your audio signal at all, but the loud passages are changed disproportionately. Loud passages are often exactly the takes where the singers give everything and the guitarist delivers his best solo. They are almost the gold pieces of your song - and you want to change them?

An alternative would be a simple track automation of the volume. So you would simply raise the quiet elements a little and lower the disturbing peaks a little. A hardware controller is almost mandatory here, because this is the only way you can try out different volume variants at lightning speed. If no motorized faders are within reach, a simple MIDI controller, which you route to your channel volume, may do the same.

A compressor changes the first milliseconds of your loudest signals and, with inappropriate control times, quickly leads to you breaking the best takes. In the worst case, this leads to a loudness competition in your entire mix and ultimately to undefined sound pulp. Takes of different volume do not necessarily need a compressor, the track automation is often much more effective here!

Play evenly

Another use case are recurring elements in our recordings that sometimes just disturb. Hissing S-sounds when singing or the recordings of a very dynamic drummer can certainly also be straightened using automation. Normally this takes too long, which is why we should use the compressor here.

The most important controls are now attack and release, because we first have to find a setting that suits the signal at all. Choose a medium release time and a short attack and only then reduce the threshold value so much that the compressor processes the signal in a clearly audible manner and attenuates it significantly. Use the attack control to find out when the loud passages of your signal still sound reasonably natural and then move the release control to a similar range. A fast attack and release time is often completely out of place in this area of ​​application.

Only then do you set the threshold value in a meaningful range, knowing that even an even higher volume would produce a very musical result. You tend to use this processing within a take; I would still use track automation to adjust the volume of different recordings.

Fetish from analogobsession.com is a free FET-style compressor. In this case, the plug-in with the settings shown provides more loudness and at the same time more assertiveness by increasing the attacks. At the top of the picture the unprocessed track, below the processing.
A serial circuit from SPL's Transient Designer with a rather slow compressor is a great combination for percussive input signals such as drum loops or drum effect signals.
We're not in a race: the fastest aren't always the best! With SSL's X-Valvecomp we generate a defined bass drum from the drum computer with the appropriate settings.
The same bass drum, but now with the "wrong" settings! The effect of the compression is now almost irrelevant, because the short times rather cause a strong distortion! In Voxengo's Span you can even see this very clearly from 400 Hz upwards.
Louder is not always better - even if, for my taste, the Waves CLA-3A is often a very suitable compressor for electric guitars, the Gain button simply tempts you to make the signal significantly louder. In order to really assess the effect, you should try to roughly match the processing to the signal.
Sometimes a sidechain goes beyond everything, here, for example, in Waves C1: target the disruptive area using the sidechain monitor and then remove precisely these annoying elements with ratio and threshold! Then use the free MJUC jr for sound shaping. from Klanghelm.com, and the processing is perfect! Who says you can only use a single compressor?

At the recording

A completely different area of ​​application is the use of a compressor while recording. In the past, this was often used to absorb strong level jumps in order to avoid overloading and clipping. With today's converter technology, this argument is actually obsolete.

Much more important, however, is that the use of compressors during recording usually leads to a completely different take and sometimes even to a more dynamic signal! A singer who sings to a playback in headphones will always maintain a certain volume because otherwise he will simply no longer hear himself in relation to the playback and his voice will be masked by the other signals. With a subtle compressor that prevents getting lost in the mix, you can easily support the musical performance, even if you don't have a professional in front of the microphone!

Whether you really record the compressor or only use it in the monitor mix is ​​ultimately a matter of taste. A short attack and release time can be quite appropriate, it depends a lot on how dynamic the performance is!

Sounds screws

The previous examples are always based on an existing volume difference. Often, however, compressors are used very simply to shape the sound and ensure that certain areas of a signal are emphasized more strongly. For example, a medium attack time with a low threshold and a short release can clearly emphasize the first milliseconds of a signal. The speech intelligibility or the general assertiveness of a sound in the mix improves when the setting is right!

With a very short attack and a medium release, on the other hand, you emphasize the decay phase of a sound and grind more intrusive attacks a little more pleasantly into your overall mix. There is also special software and hardware, such as SPL's Transient Designer, with which you can change sounds in a very targeted and simple manner. In addition, everything is really allowed for this purpose, and an "incorrect" setting may be exactly the right one!

make space

If a compressor not only has a sidechain EQ, but also a real additional audio input, you can use it to create space in the mix. A common trick is to put the bass drum on the sidechain input of the bass compressor. Here, too, it is important to find a musical variant of the attack and release times, depending on the style of music, the effect can stand out clearly!

In a guitar-heavy song, you can use a sidechain compressor to separate the lead guitar from the remaining guitar tracks by using the lead guitar as a sidechain signal for the remaining tracks.

Conclusion

Without being clear about the actual application area of ​​a compressor for a certain signal, it should not be used in the first place. Compressors don't automatically make a signal better by themselves, they can, if used incorrectly, destroy even our best and most emotional recordings!

No channel strip preset knows your area of ​​application. If you want to equalize the volume of different takes, a preset setting to emphasize the attacks will only flatten your dynamic passages in an unmusical manner.

If used skillfully, compressors will help you improve your overall mix, increase the overall volume and better coordinate the individual tracks.

Think in advance what you expect from a compressor on a track. Just because it is only a mouse click away in every DAW today doesn't mean that it is of any use to us!

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