December 7, 2011  |   Logic Tutorials, Music Courses, Tutorials

Audio Mastering Tutorial – How to Optimise Maximum Level in Waves L2 Limiter

Welcome to a new series of tutorials which give you an exclusive look at our brand new online Audio Mastering course featuring Waves plug-ins.

To kick things off Doug Shearer (mastering engineer: Kasabian, Jamelia, Guillemots, Gorillaz) looks at the Waves L2 Limiter, demonstrating how to optimise the maximum level. Before we get into the video lets give you a quick run down of the reasons behind doing this.

What is a limiter?

A limiter is essentially a compressor with a very high ratio, usually 10:1 all the way to infinity:1. A limiter is designed to prevent a signal from going above a defined level. When the input is below the predetermined level, usually the threshold, the audio dynamics are not affected; any input signal that exceeds the threshold is ‘limited’ to the defined level.

Why do we need to manipulate the dynamic range?

We traditionally compressed material to accommodate the limitations of the playback medium. For example very quiet passages could be masked by noise floor on vinyls and cassettes or too loud passages and high peaks could cause distortion. But we also manipulate the dynamic range to try to target the average listening environment. Music is not only listened at home or in the car, it is also listened to on portable players with ear buds and even on tiny mobile phone  speakers. Music is also broadcast everywhere; in towns, cafes, shops, etc… in all these situations the noise floor is very high and low passages tend to get lost. The role of the mastering engineer is of course, to deliver the best sounding quality master that will essentially sound great on great systems while still translating on a wide range of  other systems.

We can have it loud

Some music needs to be loud, some doesn’t. Some music can be loud, some cannot. Although I wouldn’t encourage you to distort your masters just to gain loudness, we need to understand that there is a place for loudness as long as it works with the music and that we don’t compromise the dynamic range. Some tracks are more sympathetic to limiting, whereas others tend to distort more quickly.

Limiters can be fairly transparent when applying little gain reduction and tend to deal better with short peaks than with slow/long sustained sounds (especially bass). This is one of the reasons why we can push the level of Hip-Hop and modern R’n'B tracks relatively easily.

It is important to realise that each track has a sweet spot where the limiter can increase the level without affecting the sound quality too much. If you follow this tutorial, carefully listen to how the transients are affected and watch out for audible distortion; there is no reason why you can’t have a good loud master.

The first track is a bare hip hop track with short peaks, the second a dubstep mix with long fat bass notes. Notice how the limiter deals better with the peaks of the Hip-Hop track than the long low bass notes of the Dubstep one.

The Audio Mastering course has been developed by JC Concato (Mix engineer: The Cure, Erasure, US3) and Doug Shearer, with contribution from top industry professionals, Jim Lowe (Producer, engineer: Stereophonics, The Charlatans) & Bunt Stafford Clark (Mastering engineer: Thom Yorke, Manic Street Preachers, Aloe Blacc). The aim of the course is to help you understand the role of the mastering process, develop/tune your ears, learn about EQ techniques, compression, limiting, as well as advanced techniques such as mid/side processing and multiband dynamics, and much much more. Each week you’ll master a choice of tracks yourself and get 1-2-1 video feedback (DVR) on your work from your tutor. Courses start: 9th Jan, 5th March, 30th April 2012

We’re pleased to be running the course in association with the fantastic Waves plugins but the skills you absorb can be applied to any mastering software or hardware.

“Mastering is one of the most important stages of the production process and we’re delighted that Point Blank have gone with Waves as their plugins of choice”

Gilad Keren, Waves Audio CEO

Keep up to date with all of Point Blank’s news, tutorials and giveaways by subscribing to our Youtube channel, or following us on Facebook and Twitter… and if you have something to say about this post, start the conversation with a comment below. Thanks!

Video Transcription:

This clip is part of a series taken from the Audio Mastering course featuring Waves Plug-ins. It’s been developed by Doug Shearer, the mastering engineer for acts such as the Guillemots, Kasabian and Jamelia.

The Audio Mastering course is designed to help you make your tracks sound like the ones you hear in the club or on the radio. To get more content like this, visit the free courses section at pointblankonline.net.

Doug Shearer: OK, so we see a limiter is for making tracks louder, and that’s good right, that’s what we want, excellent. So let’s demonstrate. Got our track, lower the threshold. And at some point we’re going to hear our loudest peak and we’ll see it on the attenuation meter at the right. Seeing a bit of activity now, louder, louder, let’s keep going up. And we’re getting louder, we’re getting louder.

We’re still getting louder, but the sound is going horribly wrong. So obviously, total loudness isn’t the only issue. And also as we get louder and louder, it’s almost not getting louder anymore. It’s almost hard to tell, which is as we listen louder, seems bigger and more impressive almost. It’s a psycho [acoustic] trick, that when we hear something really loud it seems impressive for a while.

So we need a more methodical approach to how loud we should be making it, how much we should be limiting. And so what we know about limiters, we know that the threshold is triggered by the peak level in the music. So, if we look at our track we can see what’s making those peaks.

So if we play a little, for start…
…well it’s pretty much snares. Big snare there.

…that’s pretty much the main offender in the peak department. Let’s just see how, exactly how loud these peaks are. If you go to the sample editor, we go function, search peak. This will tell us where the highest peak is. And there it is, just after bar 22 or so. We play through it. On the meter we can see it at 1.8. So we close the sample editor again.

We know that’s the highest peak in the whole track, so that’s a good guide. Because obviously we have to work with the loudest part of the track. Some tracks build and build and build, so you might want to look at the end of the track as the loudest part.

In this case, we’ve got a big peak early on and the rest of the track seems fairly even, more or less, looking at the wave form anyway. That’s some guide, it’s not an absolute truth. You still have to listen and watch your meters.

Anyway, let’s make a loop around this loud section.

And just have a look at the limiter again. Now, we’re back at our default setting on the limiter and as we’ve seen before the L2 and L3 some of the waves limiters have this very nice feature where you can gang the output feeling and the threshold control, thereby as you limit more, it turns the output down in the corresponding level.

So as you limit more, as you bring these thresholds down, we’re not going to notice any change in level. But we are going to start here and see loudness, there’s going to be a sweet spot where it sounds loudest. And as we limit too much, it’s going to start going mushy and sounds quieter in fact.

So we go down, you see we’re attenuating a bit now in some of the peaks. If we keep going, ooh, we’re starting to, it’s starting to melt the sound good now. You see it’s quieter, early on as we add a bit more it sounds, or has minimal change. And we’ve got more change and more change and it starts sounding quieter and ‘rubbisher’, if that’s a word.

So we’ve just got to find this sweet spot where it still sounds good, the peaks are controlled, but we’re not getting these distortion artifacts, it’s not sounded all kind of flat and mushy. So if we lower the threshold and add (inaudible 05:21) again and listen closely.

Still alright. Slight [pass and] check. Still sounds decent, you know we haven’t destroyed anything. Go a bit more. Now we’ve lost a little bit of the swing and the snare here. And as we know the snare is the thing that is going to be triggering the limiter and its going to be affected most by it because of that and so that’s the thing to really listen to. And we have lost some of the power, some swing in it.

That’s not necessarily the end of the world, we are mastering, and there is going to be a change sonically in the mastering process. And to a degree it’s a matter of taste as to how far you like to push things. When you start losing the power in an instrument, then it’s probably time to back off because you want it to be exciting. That’s the whole point of music it’s supposed to move you, and if it starts sounding flat then it doesn’t move you anymore.

Also worth listening to, at some point, the bass frequencies are going to start triggering the limiter as well. And that can be a problem, because limiters are quite good at capturing fast peaks, but they’re not so good at dealing with slower waves, like bass waves and they might just distort and that’s the thing to listen out for. They’re actually really efficient at just dealing with things like snares because they’re quick and they can deal with the peaks.

But anyway, let’s back off because we are hurting now. It’s somewhere around here that is kind of not a bad compromise. It seems to come across more. The music seems to jump out a bit more around this level and if we push it a more, it starts sounding wrong and it starts sounding quieter which is not what we want the track to sound like, we don’t need it to have necessarily a high level, it’s a different thing.

We’re going to go a little bit more…
…9.5 or 10 is all right. Take a little bit of a hit on the snare, and that’s fine. It still sounds good, still sounds swingy.

Now of course that we’ve found our sweet spot on the limiter, we can turn the output ceiling back up and get back all that gain that we’ve been working for. And we put it normally to minus 9.1 and that’s to catch any rogue over levels. So just out of tidiness really, we go to minus 9.1. We bypass and that’s what we’ve done, that’s how far we’ve pushed it, quite a difference, but we’ve retained the spirit of the track and maintained the sound of the track.

All right, so if we move on and look at another track, we set our limiter. And let’s go to this track, very different sound. And we can just tell from the wave former that there seems to be more going on towards the end, which is often what we expect to see. And just listen to the fat bass we have going on there.

And if we look at the peaks a bit closer, there we see the highest peaks are being caused pretty much by those big bass notes. And as we said before, that can be a problem. So it might be a different kettle of fish limiting this track.

So if we go back to our limiter and do the same trick again, we lower the gain threshold and output ceiling together by using this central button. And you see what happens; we see on the right we are starting to attenuate. And you can see that when the bass is playing that when you get attenuation, you can tell that’s what you’re affecting the most.

Ooh, do you see, it’s gone, it’s just absolutely gutting that bass and distorting it. That sounds unpleasant to my ear. None of these things are cast in stone, you have apply your own taste in mastering and make it sound wicked. But I think most of us would agree that that bass is starting to sound rubbish, and so we back off.

That’s a bit better, somewhere around there is…

…that’s kind of acceptable, it’s doing it a little bit, but that’s fine more or less. So in this track this is as far as we can probably take the limiting on this track. This excessive bass, if it is excessive, [discuss] is something we might look at when were EQ-ing, and we might balance the track in a different way before it goes to the limiter and we might be able to get more out of it, but it’d bring up more of the rest of the track.

But as it stands with the limiter all we can do is this, is just going to get worse if we hit it harder. So let’s put that level back in, put ceiling in at minus 9.1 and then AB, and again, we’ve added a decent amount of level, that’s fine. If we want to go any higher, push the level anymore, probably not to be done with a limiter, you might have to address it with a compression or EQ.