 This is an optocompressor, specifically a so-called 2A style of compressor, and given its wide use in popular recordings over the past few decades, it's arguably the king of compressors. That's why I think you should know why, when and how to use it. Hi folks, I'm Mike and I hope you're well. Optocompressors use a light element and an optical cell to alter the dynamics of an audio signal, and the great news is you don't have to understand any of that sentence to know how to use one. In fact, I'd suggest that this style of compressor is both the easiest and the most useful to learn. Renowned optocompressors include the Avalon AD2044, and much more familiar to you most likely is the LA2A, and it's that style of compressor that I'll focus on in this video. It's no surprise, of course, that this has been cloned into many plugins over the years, but in this video I'll be using the warm audio WA2A. We'll talk later about why I've chosen this specific model, and I'll also be playing some comparison demos. Now before we dive into why you would use this style of compressor, let's just have a quick recap on what compression actually does. Audio is made up of quieter and louder parts, and the difference between the two is called the dynamic range. Now let's say I want to make those quieter parts louder. I could just raise the whole level, yeah, but eventually those loudest parts are going to reach a point where they start to distort. This is called clipping, and particularly with digital recordings, this can sound very unpleasant indeed. So let's turn things down again. Now this is one of the problems that we can try to solve with a compressor. We can say to the compressor, hey, once we reach a certain level called a threshold, let's turn the signal down. Now how much we turn it down by is called the ratio. Now once we've done this, we can see that the dynamic range has decreased. The difference between the quietest and the loudest parts gotten smaller. That means that we can now raise that signal again, but it's going to take longer before those loudest parts reach that peak where they'll distort. Consequently, it means that we're able to turn the quietest parts up louder before the signal gets distortion. This is one of the uses of a compressor when we use it in two stages like this, as well as increasing things like sustain. Now how quickly we turn that signal down is called the attack, and how quickly or slowly we allow it to return back to its normal state is called the release. Now these two timing factors can have a great effect on the character of the compressor, and it's one of the reasons why you may choose a 2A style of compressor. In fact, with a 2A style of compressor, you have no direct control over attack and release. So you won't find any knobs on the front for that. Attack is set to around about 10 milliseconds, while release happens in two stages. The first over 60 milliseconds, and the second over a much longer period of time, depending on how long the signal has been above the threshold. Now on this particular model, that's between 0.5 and 5 seconds. Now it's these characteristics which really give this compressor a part of its unique style. The other is ratio. Again with ratio, we have no direct control over its value, although we can affect it with the limit compressed switch. When we're in compressed mode, it's somewhat dependent on the source material, but it's generally considered to be about 4 to 1. When we switch to the limit mode, it's much closer to infinity. However, if you're just using small amounts of compression, you may struggle to hear the difference between these two. Curiously, it's this combination of limitations which makes this compressor so useful. It all adds up to a rather fluid and natural sound. And although we've changed the level of the signal, we're generally with this style of compressor not aware of the compression at all. And that's one of the reasons why you would choose this style of compressor. More specifically, this style of compressor is known for being useful on vocals where it can gently smooth them out. It's also really well known for being used on bass, and I particularly like to use it on acoustic guitar. And we're going to hear examples of all of those uses later on. With so much being taken care of under the hood, there's actually very few controls left for us to use. On the right hand side, we have our main control. This is called peak reduction. And this really controls the point at which compression starts to occur. In other words, this is kind of a threshold control. Now on the left hand side, we have a slightly confusing control, because on many models, this is simply labeled gain. And some people confuse this for input gain. In fact, this is output gain. And this is where you would apply your makeup gain, which we discussed earlier. And really, that's it in terms of the main controls, which actually control the sound. We do have another control, which just selects what the VU meter will show, but it doesn't actually affect the sound. Now on this particular model, the WA2A, there are another couple of controls at which we will discuss later. So how does it sound? I've made a demo where I've applied the warm audio WA2A to vocals, acoustic guitar and bass guitar as well. Now, fortunately, my audio interfaces routing allows me to record both the dry and the wet signals. So I'll be switching between the two and indicating on the screen when I do so. Now I have matched the peak levels of these two signals. So any changes in loudness are because of the compression itself. Now, let me know in the comments down below if you can hear any differences in the character of the sound apart from the change in loudness. Was it the way that I stand too close that kept you running? Was it the fear of my touch? Was I too near too much too soon that kept you running just gone? Of course, apart from the loudness changes of compression, running our audio through tubes and transformers is where a lot of the subtle magic occurs. This is what hardware does and plugins try to emulate. The WA2A has a lot of that magic inside, but at a fraction of the cost of the LA2A. In fact, let's take a closer look at the warm audio WA2A. The WA2A is certainly heavily inspired by the LA2A, although I'd stop short of calling it an actual clone. It uses four quality swappable tubes, premium input and output transformers and achieves its opto compression using a USA made Kenetech opto cell attenuator. There are no compromises here with a fully discreet signal path. Apart from the controls we discussed earlier, the WA2A also has a pre emphasis control on the right, allowing us to make the compression more or less responsive to high frequency transients. Conveniently on the left, we also have a control to calibrate our VU meter. On the back, we see balanced inputs and outputs either via XLR or TRS connections, as well as connections and controls for stereo linking to units. All in all, you feel this is a well made quality piece of hardware. Okay, let's face it, I don't actually have an LA2A available to compare this directly with, but even if I did, LA2As are renowned for each unit sounding a little bit different. So any comparison would have quite limited value. In any case, it's more likely that you'll be wanting to move to a unit like this from plugins. With that in mind, I've made some demos available on my website of dry hardware and plugin versions of this recording. These differences can be quite subtle. So I wanted to avoid the YouTube streaming quality on this occasion. So just follow the link in the description down below to download, listen to and compare those demos. Of course, you can decide for yourself about the differences in sound between a piece of hardware like this and a plugin. But I feel like it's my job as a reviewer to let you know about the experience. And this is where I feel using a piece of hardware like this is really quite different. Of course, you can use this on the way in while you're recording, say an actual singer, and you can make adjustments to the control and just listen to the difference in the sound. This to me is where you have a completely different relationship with a piece of hardware. And it just feels so much better to be honest with you using a control like this. It's even better than the onboard DSP effects I have on my audio interfaces. Of course, those can also be used on the way in. But there's something subtle about the changes in the behavior of the compressor as you make those adjustments in real time using an actual knob that I just can't quite put my finger on if you'll pardon the pun, but is definitely a nicer and better experience in my opinion. Don't forget to follow the links in the description down below for both the WA2A and the demos as well. Now, if you're still confused at all about compression, you may want to check out a video I made aimed at beginners where I explain all about compression. Just follow this thumbnail here to watch that. Thank you so much for joining me today and I'll see you in the next video.