Compression is one of the most important tools in the music industry as well as other forms of media, it helps control the dynamic range as well as help you have control over clipping and other aspects of an audio recording. That is why it’s also important to have a closer look at one of the most important knobs in a compressor, one that can often be misinterpreted, poorly used, or just straight-up ignored, when in reality, you need to be very aware of what it’s actually doing.
In this article, we’re going to help you understand what the “Ratio” means in a compressor, what it does and some of the basics to get a good idea of what to do when you are using a compressor to get the best sound possible.
What is an Compressor Ratio?
What you essentially have in your hands is how much gain reduction your compressor will apply after the signal goes over the threshold level you set, this means that if you set up a ratio of 5:1, it means that for every 5dB, the sound of the recording goes beyond that limit the compressor will increase its output by 1dB. In other words, this knob will control how hard the compressor will control or limit a sound.
If you want to use the compressor as a Limiter, you would have to use a lot more compressor ratio to reduce gain and control the audio signal.
But how exactly does it work?
Well if you don’t have a clear idea of what a compressor ratio does, in its most basic idea, it will control the amount of compression applied to the audio signal. Still, as you may have noticed, there is not one number to indicate the amount of ratio, there are two.
The first number will indicate the input and the second one will be the output, so if you set your compressor to 5:1, what this means is that the signal needs to go beyond 5dB after the threshold, in order in order for the output to increase by 1 dB.
If it’s your first time learning about compressor ratio, you might still be a bit confused, so let’s have a closer look at these numbers to give you a rough idea of what some possible settings might mean for your compression.
If you set the ratio to 1, the input and output levels will be the same so nothing will happen.
At 2, you’ll get a very slight compression, this will allow you to control the signal will still maintaining the dynamic of the overall sound.
This will give you a more moderate compression, you’ll start to notice it more and the peaks will start to go away but it will still give you a natural feel, for example, if you use this setting on a singing voice, you’ll notice that the dynamic of the voice when it gets louder will still remain but you’ll be able to control higher frequencies, and peaks that might ruin the take.
At this level it starts to get into tone and loudness difference, you’ll get a stronger more aggressive feeling of compression
This starts to get into limiting territory, which means that you won’t get a lot of dynamic range and it can be dangerous if you want to maintain the natural flow and dynamic of a signal.
20: 1 Setting
At this point, you won’t get anything to go beyond the threshold, which will give you a very controlled sound, which can be helpful for some things, depending on what you’re looking for.
Keep in mind that not every compressor is the same, so you’ll have to familiarize yourself with it in order to truly understand how the ratio works on a specific compressor, sometimes you’ll notice that a 2:1 for some is a lot more aggressive than others, but, regardless of the few differences between compressors, the basics are still the same.
Speaking of basics…
How to Properly Use Compressor Ratio
A lot of what it means to use a compressor ratio properly comes down to preference and the specific type of sound that you’re working with, so it’s not like there is a magical setting for everything, it will depend on the type of signal, how it was recorded, where it was recorded, what was recorded, and of course, the input volume that you have.
Still, there are a few basic things you need to know in order to be able to get the sound that you want by modifying the compressor ratio. You can get different sounds by having different ratios so let’s go over some of the basics to get you started.
If you use a lower compressor ratio you will get a natural sound, this will allow peaks to stay mostly untouched while also having a bit of compression to control the hard clipping.
This is better to give you a punchier fuller sound, for example, this is used for drums a lot of the time in a mix so that it feels heavier in the overall end result.
The best example of heavy-ratio music is pop, where there is a more processed and in-your-face type of sound that works perfectly for the radio. When you see the sound wave for music like this you will find that there is not a lot of dynamic going on, but rather a more straight line at both ends.
You don’t want to abuse limiting as it will completely stop the signal from going past the threshold. This will get rid of any dynamic range while also adding a bit of distortion to the signal, so it can be an interesting tool, but one that needs to be used with caution
Compression is very important in a mix and audio in general, and it cannot be overstated how important it is to actually know how to use it, since it’s not just about controlling clipping, there are changes in dynamic, tone, distorting signals and more that can all change with the turn of one knob, ratio.