Compression: A Quick, Easy Guide | Steve Perrino | Skillshare

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Taught by industry leaders & working professionals
Topics include illustration, design, photography, and more

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Taught by industry leaders & working professionals
Topics include illustration, design, photography, and more

Lessons in This Class

7 Lessons (18m)
    • 1. Introduction

    • 2. Compressor Overview

    • 3. Threshold and Ratio

    • 4. Attack

    • 5. Release

    • 6. Makeup Gain

    • 7. Conclusion - Dialing it In

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About This Class

What is compression? How does it work, and why do we use it?

In this short demonstration, I discuss the parameters of a typical compressor, and how they affect and shape the sound. There's a lot of information out there on compression, but my goal of this course is to provide you with clear and understandable explanations for understanding the workings of a compressor. 

Meet Your Teacher

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Steve Perrino

Producer / Audio Engineer / Songwriter


Steve Perrino is a Producer, Songwriter, Mixer, and owner of Compass Audio in Akron, OH. His philosophy is to capture the natural energy of a band’s performance while allowing a song's arrangement and instrumentation to evolve throughout the recording process. Alongside producing, Steve is also a songwriter with Heartbeat Music Group and a guitarist in The Grievance Club.

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1. Introduction: thanks for checking out my class on how compressors work. My name is Steve Perino. I'm a producer and audio engineer based out of Cleveland, Ohio. I hope this video is a clear and concise explanation on what compressors are, how we use them and why we use them. I'm not only gonna be going into the different parameters of a compressor like attack, release and threshold, but I'm also going to be going into different techniques and applications for compression, like how we use them differently for drums as opposed to vocals or base. So let's jump right into the first video, which will just be an overview of the compressor. 2. Compressor Overview: All right, So here is my overview of a compressor. I'm gonna be using logic stuck compressor. Ah, I definitely recommend starting with whatever stock compressor you have in your Daw. The controls are always laid out very cleanly and clearly, And so it's a very good thing. Toe learn on. So logics has some extra stuff going on over here. We're not gonna worry about that. We're just gonna worry about this center section right here. These are the main controls, and this is what's going to be on most compressors that exist. So on this compressor and most of them, there is a threshold which is sometimes called input ratio, makeup gain or sometimes called output, attack and release. This is the core of compression. And the biggest thing to understand and take away from this is that all five of these are related to each other. Your compression sound is the relationship between these settings. All of these served their own independent functions that will be going over. But compression, in a nutshell, is just an automated volume knob. That's all you're doing. You're setting a point to where you want to start compressing the signal and then all these controls are just basically saying how they're going to do it. So it's pretty much a simple is that And it's from that point. It's just understanding what your goal is. Do you want to squash your sound like a vocal like, Are you really trying to tame it? Or are you just trying to even it out a little bit? Or are you just trying to get a little bit of color or flavor in your sound? These air all different uses for compression, and there's different ways to go about it, so let's get into it. 3. Threshold and Ratio: So let's start off with talking about threshold and ratio. So these two are pretty intertwined with each other and with how they relate. So threshold we have this set at negative 20 db So we're not saying that that is the maximum output that we're allowing. All this is saying is that negative 20 db is going to be the reference point in which this compressor works and you'll understand that a little bit more in a sect so ratio, as you can see, which is just a ratio of some number. Toe one is representing the relationship between the input and the output. So this first numbers input the second numbers, the output. So with 2 to 1 here, what this means is, if the input of our signal is two decibels higher than the threshold point that we set, it's only going to output one of them. So in an example, if our input signal is negative 18 decibels, which is two decibels higher than this threshold, our compressors only going toe output one of those decibels which will bring our input signal to negative 19 decibels. Now, if our input signal was negative 10 decibels, which is 10 db higher than this threshold. It's going to output five decibels because with this ratio, it's essentially saying, if the input is too than the output is one, so it keeps going up by that ratio. So if the input is 10 then it's gonna output five. And if the input is 20 higher than is going to output 10 decibels, so with the 2 to 1 ratio is essentially having it. But let's look at a different ratio. Let's look at it 10 to 1. So this is saying, if the input is 10 decibels higher than our threshold, it's only going to output one of them. So, with our input signal coming in at negative 10 decibels, which is 10 decibels higher than our threshold, it's on Lee going toe output one, which means that our input is going to be reduced to negative 19 decibels, which is essentially nine decibels of gain reduction. And that principle works with any ratio. So I hope you see that ratio and threshold can be a little scary at first, but that it's a pretty straightforward concept. You got to do a little math in your head, but once you understand it, you'll get a feel for it and basically understand in a nutshell that the ratio is saying how much it's going to compress the signal in the threshold of saying, At what point is it going to start compressing? So next we're gonna talk about attack. 4. Attack: So let's talk about attack. There's a lot of misinformation out there on what attack really is, some people say, and I grew up learning that attack is how long it takes for the compressor to start working , and that's not true. Attack is the amount of time that it will take your compressor to get to maximum gain reduction that you've set with your threshold in your ratio. So let's go back to our previous example of 20 decibel threshold and 2 to 1 ratio. So if our input signal is negative 18 which is to DB higher than our threshold, and we have our ratio set to tow one, then at maximum gain reduction, it will get one db of gain reduction. So attack is saying, How long is it going to take for the compressor to bring it down? That one decibel, is it going to take 10 milliseconds, or is it gonna take 200 milliseconds? So the rial thing here with this is that sometimes you don't have 200 milliseconds before the next snare hit comes in, for example, so sometimes there isn't enough time for it to get to maximum gain reduction, so I have logics graph mode here, and I'm just going to show you graphically what I mean. So I'm gonna increase this ratio a little bit just so we can see it. So let's go to a medium attack. As you can see, it's compressing by a few, and it's happening immediately. Right? When you see this hit happen, it starts compressing. Even though I have this set of 40 milliseconds, it's starting right away. So now let me get a quicker attack time still happening right away. But we're saying Get to maximum gain reduction right away and that's what it's doing immediately. Getting down toe negative, 20 decibels. But now let's slow down a lot Notice we didn't change any of the threshold or ratio settings or anything. Everything is still the same, but we made it so that were making it 152 milliseconds before it gets to maximum gain reduction. So the only difference is that this hit here is too quick. It's quicker than the attack time that we're setting, so it can't get down to maximum gain reduction fast enough with the attack. Time that we've set the attack also affects the tone and the color and sound of the signal coming in as well with a snare. If you have a quicker attack time, it's going to really increase some of the punch because it's going to accentuate the very, very, very beginning transient and bring down the rest where over here it will be a little more splattered and bring out some more overtones, and that is pretty much attack. In a nutshell. Let's move on to release. 5. Release: So let's talk about release. So release is also measured in milliseconds. And what we're telling the compressor with this knob is how long we wanted to get back to normal, how long we wanted to go back to the UN compressed version of our signal. So at this speed, we're basically saying, once it's compressed, we want it to go back to the UN compressed version in 150 milliseconds. So with an average ratio for the one pretty high threshold so that we can really see what's going on and medium attack, let's see our track. So it's going down and going back up it a pretty even rape, which makes sense because these are pretty even relative to each other. So let's speed it up, get a really fast release, So notice there's not as much gain reduction because we're saying, get back there as soon as possible. So even if you can't reach maximum gain reduction, get back to normal faster. Now let's get a longer release time. Notice forgetting morgaine reduction because we're allowing the compressor now to stay down here, which means you saw this slope down as I increased it and That's because eventually it got down to maximum gain reduction. But we're not allowing it to get back up because thes hits air coming in quicker than the release time that we set. So it's going to stay compress, and it's not gonna quite make it back up unless we speed this release back up now. A lot of compressors also have this auto release feature, and as you can see when I click that, it's it's working in pretty good time. It's working with the tempo of the song in a cool way. But sometimes this auto feature isn't quite right, especially if you're doing something like compressing Ah, whole master of a track or a whole drum kit. Sometimes it'll work. There are some compressors that are really good at it, but most of the time I would say you're gonna want to spend the time to dial it and manually because, just, like attack with release, you're gonna wanna have a specific goal in mind, you know, Are you gonna want that really quick release? Are you going to 12? Have that more compressed feel unlike that longer compression of a longer release time. So like I keep saying all these are related to each other. They all work differently in produce, different results based on how based on the relationship between all of the's. So next we'll talk about makeup gain. 6. Makeup Gain: So the last parameter on a compressor that we're gonna talk about is the output or the makeup game. The reason why this is here is because, like I said, compressors, essentially an automated volume knob that we're turning down. So we need a tool to be able to bring it back up to the volume that we originally had it at because there's probably a reason why we recorded it at that volume. So in this example, you can see that it's bringing the average volume down almost negative 15 decibels. So we probably recorded it to peak around here and now it's down here. But if this is the compression style we want, we shouldn't have to sacrifice that. So we just used the output knob to bring it back up to where we need it to be. And it's pretty much a simple is that so? Then you make sure your gain staging is good so that it hits the next plug ins at the right volume, and so that the only thing that compressor is doing is shaping the dynamics. It's not just turning down the volume of your signal, so other compressors have. This is Well, there's usually an auto gain feature. Um, this can sometimes be helpful and convenient, but just like the rest of these, a lot of time you're just gonna want to spend the time to make sure that you're doing it manually because it doesn't take that much effort physically or mentally to set this output exactly where you need it. And then you'll never have to worry about whether this auto gain is hitting it correctly or not. So that is pretty much output and sums up the basics of how a compressor works. 7. Conclusion - Dialing it In: so that is essentially how compressors work. There are a lot of different varieties of compressors with different features and functions and sounds and styles, but it really boils down to what I went over in this video. If you have any other questions, please let me know. I'd be happy to answer them or explain this a little bit more in detail. But please also try the project I have for you. I gave you the raw files for the snare track and rob vocal, and I want you to load these into your Daw and try out some different compression settings on these so that you can see how different styles of compression can really change not only the dynamics, but the vibe in the tone of your track and a great way to really dial in. A compression setting is to max out the settings so that you are hearing a very exaggerated version of what you're gonna be doing to your signal, and then you can dial it back from there. So I like to start with the maximum ratio that my compressor allows me to dio So on my compressor that I was using, I can do 30 to 1, I believe, and then set your thresholds where you're getting about 10 to 15 decibels of gain reduction . So that's going to sound pretty extreme. But again, it's just so you can really noticeably here what you're doing. And then from that point, start tweaking the attack. So on the snare track, you'll hear that when you go to a quicker attack, it starts to minimize the amount of overtones that happen after the hit and really just emphasized the initial flak of it. Where if you go to a slower attack, it starts to sound a little splatter, and you can really hear the overtones that come out. So thank you so much for checking out my class again. If you have any questions you can ask here or email me at Steve at Compass audio recording dot com, and I'll see you in the next class