The next device I'd like to look at is the downward compressor. Now, when someone says put a compressor on it, or just someone refers to a compressor, they are referring to a downward compressor, which is reducing the level of the louder things. There are upward compressors, which bring up the volume of the quiet material, and that is an important tool, but when someone says compressor, they really are referring to the downward compressor. It's a really important tool. It's one you really need to understand the fundamentals of, but don't expect to master it in this week. It's gonna take you a long time. It really is hard to hear what this does. Mainly, because the inbuilt gain control that we talked about earlier, it's always functioning. And we're also not really trained to focus on the fine points of volume, it's a tough thing. So, the goal of a compressor is to reduce the level of the loud stuff. We set a threshold and that's the point where the compressor starts reacting, as the envelop gets above that, the volume comes down, to reduce that level. The speed that that volume moves in, how fast the reduce of the level, is your attack and your release time. And they have a really important role in a compressor. In a compressor, one of the main things you're doing is trying to control that transient. That initial sharp moment that happens, like when a snare hits or a kick drum hits. And it's really fast, and that attack time controls whether the compressor brings down that initial attack or not, and if you increase the attack time, it will actually let through that transient, and if you reduce the attack time, it'll stop that transient from happening. So, the thing is, there are many ways in which we can use a compressor. It's not just to reduce a transient. Because how I adjust that attack and release time can really decide whether I let that transient through or not. So, it's a complex device, and all the controls are interrelated. Were going to take some time today to learn the fundamentals of it, and I really hope you go to the discussion boards and talk about the many ways a compressor can be used, and the different types of compressors. We find that, in the abstract here, we talk about it as if it's this simple formula. This kind of on/off, if it crossed the threshold it does this, if it doesn't cross the threshold it does this. But the truth is, it's a little more complicated than that. There's always fine details like, does the volume fader move down linearly? Or, does it have a curve to how it moves? And all these things are in the design of the plugin or the piece of hardware. So, I find that choosing a different compressor can have a major impact on the sound of it and how it actually shapes the sound. So, bring that up in the discussion boards. It's a great discussion to have, and I really hope you do expand on this topic. But right now, let's look at the fundamentals of compression. >> Now, we're going to look at the fundamentals of compression. And like with the gate example, we're going to start with kind of a non-musical example just designed to show us what the controls are. And then, we'll move to a more musical example afterward. The sound we're using this time is a synth patch I created that just changes in volume drastically. Let's hear it. [SOUND] So, it just jumps up and down in volume. [SOUND] Now, we don't really need to hear it that loud. All right, now, we're going to see how compression functions on the sound. The first thing we'll do is put the compressor in limiting mode. So, we're gonna do quite, quite a bit of compression. I'm using the ratio all the way up to 30 to 1. Again, I think, it's important to hear what the effect is in the extreme. And then, you can back off and use it in a more musical manner afterward. Remember, that our transfer function is this diagonal 45 degree line, meaning input does equal output. And right now, we won't do anything to the sound. If I want to have an impact on the sound, I have to lower my threshold. [SOUND] And I'll lower my threshold right to about here, which is just above the quite moments in the sound, and let's see what this does. [SOUND] So, we're seeing that the compressor is automatically reducing the volume of the louder moments and keeping the quieter moments quiet. So, you can see we've dramatically reduced the dynamic range by compressing or lowering the volume automatically when the loud moments occur. We're using a high ratio, so this is having a very dramatic effect, and we end up having a quieter overall sound. Now, a common approach of a compressor is to reduce the dynamic range, and then bring a volume of everything up at the very end. This will increase the perceived loudness of a sound, really by making the quiet stuff louder. And, that is what the output gain section on a compressor does. So, if I have the sound like this now, I can increase the output gain of it dramatically. [SOUND] And we can see that there's very little dynamic range, and in effect, we brought up the level of the quiet moments. So, that's a common usage of a compressor. Now, most compressors will also include some sort of auto gain or auto makeup gain option. I prefer to keep that off at all times, so I am manually and purposefully adjusting all the gain stages. When you have an auto gain section on, the device will automatically increase gain, and it's hard to know exactly what the compressor or gate is doing in those instances. Let's see the sound again. [SOUND] If I was to decrease ratio, it's going to decrease the extent of the compression. I'll put this now, at 4 to 1 instead, [SOUND] and we see we have more [SOUND] of a dynamic range, a decrease in the compression as I reduce the compressor. Reduce it even more [SOUND] and those dynamics are allowed to happen. [SOUND] So, the higher the ratio the more compression that will happen. Now, I find the tough part about compressors is knowing how to handle attack and release. They seem a little backwards at times, so I'd like to point out with this example how attack and release are functioning. Remember the compressor's role is to bring the volume down. An attack is how fast it does bring the volume down. So, like we do with gate, I'm going to play the sound, and I'm going to change the attack time. This time, I'm going to increase the attack time as the sound is allowed to play. So, this right now is a quite fast attack and that we're stopping the transient drastically. If I want to let that transient through, I increase my attack time. As I increase the attack time, that transient hits before the compressor has a chance to react. We see this yellow line here showing us the gain reduction of the compressor. And we see that it's reducing at the beginning of every one of those hits and as I increase attack time, it's reducing slower, so it's letting that transient through. [SOUND] And we have a very different sound. Very often we keep attack time quite low, so that we do have an impact on that additional transient. [SOUND] And you see how we can kind of craft that transient with this control. If I want to have a punchy sound that allows that attack to come through, a high attack time. If I want to stop that transient at all costs, I have to use a very low attack time. And as I reduce this, we'll get back to the point [SOUND] that transient is never allowed through. Now, another difficult control on a compressor is your release time. And again, this is going to control how long it takes the compressor to come back up after the sound has reduced below that threshold. Let's try this same thing, and increase our release time. [SOUND] So, you see with a higher release time, we can get these kind of pumping sounds where the sound slowly comes in and it can be quite obvious. So, as you can imagine, you really have to craft the attack release ratio and threshold controls every time you wanna work with a compressor. It can be quite difficult to know exactly how to set all these different controls. We're going to apply it in a musical context on a bass line now to see some good settings for this. But I hope you're getting a feel for just how these controls do function in the abstract. Now, I'm going to try to compress my bass line, so it's a nice, consistent bottom end for my entire mix. Let's hear the bass line now. [MUSIC] So, the timing is good. It fits in with the drum grooves rhythmically well, but I feel like the dynamics are a little bit uneven. As you're watching the wave form display, you saw some hits were a bit louder than others, and there's just a consistency that we'd like to have in the bottom end. So, first thing we have to do is start to set our threshold. Let's have a look at this bass line. And I'm going to mute the drums for now. [MUSIC] And I'll set my threshold. [MUSIC] So, we're crossing a threshold pretty regularly. Once I've done that, I'll start increasing my ratio. [MUSIC] We'll let it go back to the top and I'll go up to a heavy compression of about 4 to 1. [MUSIC] And immediately, we see how even this performance has become. Every note has roughly the same decibels, and even the smaller hits, those kind of ghost notes, are much the same volume. Now, I can increase my gain by the top. [MUSIC] So, I was able to increase the gain by 7.5 decibels. I have a much more consistent performance. [MUSIC] Now, if you listen carefully though, what this has done, and an important thing to realize that happens, is it's brought up the noise. In fact, you can hear a little bit of a radio station that got into the bass performance that my cables must have picked up a little bit of a radio station noise there. And you can kind of hear it during that last little bit. Let's hear it again. [SOUND] So, just be aware that that make up gain on a compressor is a gain stage, bring up the level, and any noise that's already in your performance will be amplified by the compressor in this instance. Now, let me mention the attack and release settings that I am using here. You noticed that I have totally stopped the transient. [MUSIC] Right, if I was to increase the attack, let me decrease the output gain, so we don't go clipping here. If I increase the attack, you'll see some of those initial transients will be let through. [MUSIC] See how the beginnings and notes get a little more pronounced now? [MUSIC] One more time. [MUSIC] The clicks at the beginning of the notes are much more pronounced with that attack time up. If I bring this back down. [MUSIC] We totally flatten off the waveform completely. So, when you have a low attack, you're functioning very much like, I'm never gonna be able to get above this setting because the compression's going to react so quickly. So, really important parameter and I really suggest that you get comfortable manipulating that attack setting. Again, if I increase attack, we're gonna hear less compression that initial transients let through. And I like something like that. It's nice to have a little bit of those dynamics in there. You'll still be able to increase the gain a bit. The bass is going to sound a bit more natural this way. [MUSIC] Let's hear it with the drums. [MUSIC] The bass stays nice and present with the drum groove. I can actually lower the bass volume a little bit now. [MUSIC] It stays in there nice. [MUSIC] So, we find, generally, that heavy compression works on bass cuz you want a very consistent bottom end to your mix. You might find that as you get up to the higher instruments, like vocals and guitar. You might want to use a bit less compressions, that would be higher threshold settings and a lower ratio. I'd like you to take a moment to go to your DAW and play with compression. First, just find a compressor device that you have and see if you can identify the parameters. Locate the ratio, threshold, attack, and release controls. Then make for yourself an experiment. Put in maybe a drum hit and repeat it over and over and see if you can stop the transient, if you can let the transient through. See how you can manipulate that sound using these devices. Again, work in the abstract first. Make sure you understand what all the controls do and you'll start hearing the sounds of it as you use it in extreme sense. And then when you go to apply it in the musical context, you'll have the knowledge to do so effectively.
