When making music, there are countless different effects that producers and musicians can use. Some of these effects are incredibly noticeable and instantly jump out at anyone who hears them. Distortion, chorus, autotune, and several other effects like this are very easy to hear and identify in a mix. They tend to grab the listener’s attention and pull them into the song in a new and dynamic way.
But some effects, like compression and limiting, aren’t quite so obvious. In fact, many people don’t even consciously notice these effects without years of training their ears. So why would producers, mixing engineers, and musicians swear by these effects so much?
It’s because they take good sounds and make them great. They pull together how the song sounds in a way that makes it palatable and professional sounding. Compression and limiting make the mix fit together and make individual instruments and tracks sound as good as they can be.
Many people confuse compression and limiting because it seems like they do a lot of the same jobs. They make sounds fit together and make sure that one isn’t standing out too much. But when it comes down to it, these are two very different effects, even if they might have a similar structure. The differences between compression and limiting are subtle, but they can make all the difference in your music. Here is what they are and how to use them.
What is Compression?
Compression is meant to be a subtle effect. Used too aggressively, and it can crush the sound that’s going through the effect by flattening the dynamic range and making the sound feel anemic. But used tastefully, compression can bring life and energy to a mix.
Compression is like the salt of music. Too little, and it feels bland. Too much, and it almost hurts to consume. But just the right amount adds a professional X-factor to a mix.
To understand compression, it’s critical to understand how it works. Fundamentally, what compression does is turn up the quiet parts of a sound and turn down the loud parts. It is an automatic leveler to the amplitude of a sound, and its job is to make it so that every moment of the sound is pleasing to listen to.
Most compressors have a few basic controls. The first one is the threshold. This is the level at which the compressor turns on once the audio signal level passes it. The second control is the ratio. This is how much the compressor will turn down the signal after it crosses the threshold, with larger levels meaning the signal is turned down more. The last common control on a compressor is the makeup gain. This is essentially the output control at the end of the compressor that can turn the sound back up once it’s been turned down by the compressor.
Additional controls that are often seen on compressors and attack and release controls. The attack control determines how long it takes a compressor to activate after the threshold has been crossed. The release determines how long it takes the compressor to turn back off after the sound level has gone back under the threshold.
An Example of Compression
That may seem confusing, so here is an example. A snare drum is playing, and a mix engineer turns on a compressor on its channel strip. Every time the snare drum hits hard enough that it crosses the threshold, the compressor turns it down by however much the ratio determines. If the attack is slow, it will take a longer time for the compressor to activate, allowing the initial transient of the sound to pass through. This helps the mixer to keep the snare from intermittently being too loud while still letting it sound natural.
Another important thing to know about compressors is that most of them tend to impart specific qualities onto the sound. A digital compressor will likely be very quick and efficient, but analog and analog modeled compressors tend to have very different characteristics. For example, an LA-2A style compressor will sound very different from an 1176 style compressor. Learning how all of these different compressors sound and work with one another can give a lot of depth to the way that you mix a song.
A compressor is used to shift the dynamics of a specific sound. Most compressors can be used very subtly in a way that may not initially be all that obvious, even to discerning listeners. Compressors will make a sound feel much more cohesive and consistent and make a mix sound much better.
What is Limiting?
Limiters do some things very similarly to compressors, in that limiters will turn down the amplitude of a sound if it gets too loud. However, that is usually all the limiters do, and it’s what they do best. They are generally used much less subtly and are the last tool that many mixers will use to make sure that a sound or mix doesn’t go above a certain level of amplitude.
Limiters are essential to mixes because they make sure that nothing clips and that everything comes together. When the amplitude is too high, it can often cause clipping, whether it’s on an individual sound’s track or on an entire mix altogether. Unintentional clipping is something that can almost entirely ruin a mix. Limiters catch those highest peaks of amplitude and make sure they don’t go above them.
In terms of the compression settings, a limiter is when a compressor has a ratio of 10:1 or greater. This means that the limiter is working very hard to make sure that the incoming sound does not cross the preset threshold. This makes the limiter an important part of mix busses and mastering chains because it will make sure that the entire mix stays together in a pleasing way that doesn’t cause additional clipping or distortion in a signal.
A specific limiter known as a hard limiter will ensure that absolutely no sound escapes above the threshold. These are often placed very last in mastering chains to ensure that no peaks get through that upper ceiling of sound.
Limiters are the effects that mix engineers and musicians will use to ensure that all the sounds that go into it stay within a specific ceiling of noise. They often have less character than a typical compressor but are very good at making sure that certain levels are not surpassed.
Often, the best way to learn how to use compression and limiting is by simply just using them. Open up your DAW, throw some sounds in, and start messing around with the effects. However, this can often be frustrating or confusing when you don’t have quality sounds at your disposal to work with.
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