The final dynamic processor that we're going to examine this week is the

limiter. Now a limiter is an extreme downward

compressor. So it's a downward compressor with a

ratio set very high, above 10 to 1. A ratio we tend to consider.

Is a limiter. But the role of the limiter has been kind

of changing in contemporary music. The original role of a limiter was just,

was to stop peaks. Was to make it so the signal never goes

above a certain level. And in that, it was very, it was very

useful. You think of a live stage situation

Think if you have a, vocalist. Right.

And they tend to just drop the mic or swing it around or scream into it, and,

you don't want to hurt your audience. So you put a limiter on that microphone

so that if they do drop it, if they do scream into it, the level never gets

above that specific set point. That threshold.

And you set that so that the, the loud sound doesn't hurt your speakers.

And doesn't hurt your audience. So it had a kind of protective role.

And in that, you want to make sure the sound never gets above a specific level,

so it would be a compressor with a very fast attack, and even a little look

ahead, and also a very high ratio. So you would think of it as, you might

even hear the term a brick wall limiter, meaning it's never going to get above a

specific level. Now in that instance, those limiters tend

not to sound very good. They have more of a protective role.

And at that they're very good at but they don't really sound great as you get to

them. As we've kind of moved on through

technology and get more digital signal processing, the role of a limiter has

kind of evolved to be a loudness maximizer.

And some plug-ins are actually calling it then, calling it that now.

And so an original limiter. As a protective device would just come on

once in a while, right? hopefully not even at all, but when it

did, it would just turn on and turn off very quickly, trying to be transparent,

and just protecting the audience. And the contemporary limiters, which are

also known as loudness maximizers, they're kind of running more often, and

their goal is to make things sound as loud as possible.

But not increase the amplitude, right? Remember that distinction between

loudness and amplitude? Amplitude is measurable but loudness is

the perception. So the idea with this contemporary

loudness maximizers is to make it seem louder but not actually increase the

volume at all. So we're going to examine the kind of

traditional role of a limiter and kind of also look at how a loudness maximizer

functions in a contemporary mix. We mentioned earlier that a limiter is an

extreme compressor: it's a compressor with a very, very high ratio.

And, to function as a brick wall limiter, it also has to have a very fast attack,

or a low attack time. That way, it will capture and stop all

the transience, so nothing is allowed to get above that threshold.

I have this compressor set up to be in one of these very fast attack and release

limiting modes. And the reason I'm bringing this up now,

is I want to point out the issues involved in heavy limiting.

heavy limiting in compression is a, is a common thing in contemporary mixes.

You want to make things sound as loud and powerful as possible.

But In doing so, you do introduce the chance of distortion.

And we have to be aware that we always have this dynamic range.

This issue between noise and distortion. We saw earlier that using compressors

heavily and using the make up gain increases the noise.

And now we'll see that pushing compressors and limiters too hard

introduces distortion. And it's always your job to stay between

those two things. Or when you go beyond them to do it

musically. So we'll start this example like we did

the gate and compressor with the more abstract example.

And I have a low sign wave tone that I'll play through this plug in.

[SOUND] So we see with the sign wave that we have energy at a single frequency.

[SOUND] [SOUND] And it's quite loud as it is.

Now I'm going to start compressing this signal with a very fast attack and

release compressor. Basically I'm in limiting mode now

[SOUND]. And I'll reduce my threshold.

Watch what happens. [NOISE] We see that limiting this with a

very, very fast attack and release has distorted the wave shape, and has given

us a series of upper harmonics. We've, we have distorted the signal, and

this looks very much like the clipping distortion we analyzed earlier this week.

So we have to be very careful with limiters and compressors and even gates

not to get in the situation where we're adding up our harmonics that we don't

want. Now this can be used musically but

usually you set up a compressor to avoid this kind of situation.

This is most commonly a problem with low frequency notes, like I have in this

example here. Because the attack and release time on my

compressor are set so fast, that the compressor is responding to every single

oscillation of that low wave form causing this distortion.

So if we want to remove this we have to start manipulating our attack and release

times but there's always trade offs. Let's try it out.

This time I'll start raising my release time.

And we see that's. Changing the distortion, because that

compressor's not allowed to move as fast, we're reducing the amount of distortion.

I'll raise up my attack time a bit. A little more release, and now we're to

the point where I don't really have audible distortion -- I don't see the

distortion here and I also don't hear it in my headphones.

So now I'd be free to lower this threshold even further.

I'm reducing the sound without introducing unwanted distortion.

The trade-off is this. If I play a key now, if I play this note,

we're going to see a little bit of that transience let through.

Let me make it more obvious by increasing attack even more.

So we see a little bit of that transient at the beginning of the note.

The limiter's not moving fast enough to avoid that initial click.

So that's the trade off we're always working with, with limiters.

We want very fast attack times, and fast release times if possible, but when we do

so, we introduce the chance of distortion.

If we increase the attack time, we introduce the chance that something is

going to get through the compressor or limiter.

Let's look at how a limiter functions now.

And we'll see, it's going to be very similar to this, but I want to show you

one difference. In a limiter, we have a threshold control

that is directly associated with a makeup gain.

So as I lower threshold, it automatically brings up the output gain.

And we're going to hear, this is going to be very similar to what we did with the

compressor. Let's try it out.

I'll start lowering the threshold. But this time you see.

[NOISE] It's actually bringing up the output automatically.

Watch, see that waveform get bigger. So with the limiter, as you lower the

threshold, it actually increases output in automatically.

This is bringing up the level. [NOISE] Look what happens.

Right when I cross that threshold, we get distortion.

Just like we did with the compressor. Now, we have a speed control on this

limiter, might be called release, on other limiters, but increasing that can

reduce that amount of distortion, just like the release on attack controls on

our compressor reduce the chance of distortion there.

So we're finding these same controls between compressors and limiters, the

only difference here is really how this threshold works.

As I lower the threshold in a limiter, it also increases the output gain

automatically. It's like having auto gain on in one of

your compressors. We're going to end this examination of

dynamics processors by compressing a drum groove.

And we're doing this because we have to train ourselves to hear compression

before we can actually use it in a musical manner.

I think in a week and with these lessons that we've done, you should have a good

foundation for how these devices work. It's going to take much longer to first

be able to hear them. And then be able to apply them musically.

So this is an experiment I would like you to run for yourself.

You're going to load up some kind of drum groove played by a real drummer that has

a little bit of room around it. And we're going to compress it heavily.

And I want you to observe how the sound changes and how you can manipulate that

drum groove with a compressor. It's a great way to start hearing the

effect of compressor, start knowing what it sounds like, and start understanding

how the different parameters in a compressor impact the final product.

So let's hear the drum groove now. [MUSIC] So this is the uncompressed drum

groove. What I'd like you to do first is increase

the ratio quite high, set your attack quickly in the millisecond range, and you

release in the hundred millisecond range. Doesn't have to be precise.

And then as it plays [MUSIC] start lowering threshold.

[MUSIC] When the level goes down bring up the make up gain a bit [MUSIC].

And then start observing what are you hearing differently.

Can you describe the change that you are hearing in this.

[MUSIC] . I'll go even further.

[MUSIC] So what I notice is now the high hat seems to be at a much more similar

level to the kick and snare. It seems to even out the hits so they

sound more consistent. I'm noticing more of the subtle snare

hits that are in this groove. There are some very quiet subtle snare

hits, those seem to have gotten louder as I did this.

I'm noting, noticing much more of the room tone.

So, it feels like I've added reverb that, to this in a way and that every, all the

room has gotten louder. And it also seems like the sustain of the

cymbals is now longer. Let's hear it both on and off.

Here's it off. [MUSIC] And then with it on.

[MUSIC] Now I'm adjusting the Make Up Gain so they end up about the same level.

[MUSIC] That last cymbal seems to last much longer.

[MUSIC] This sounds much drier. [MUSIC] I feel like I'm losing the attack

on the individual drums, like it's kind of muted in a way when the compressor's

on. So this is the experiment I'd like you to

try, is listening to a drum groove and compressing it heavily and being aware

kind of an analysis of what you're noticing.

You know, see what changes, and then manipulate these things in a logical

manner. So what happens if I start increasing

Attack in this situation? [MUSIC] Oh look, the transients come

through more. I start noticing those individual

transients punch through. We get like a heavily compressed sound,

but we get these punchy transients. If I reduce that a tack those transients

go down. [MUSIC] If I increase Release, or

decrease the Release. the decreased Release has a really

[MUSIC]. So with that quick release we hear that,

kind of, room tone really punch in with each hit and kind of edge we get that

pumping sound that we try to avoid, so a careful adjustment of release on a drum

groove. It's going to have a major impact.

So with really slow, we really notice that noise.

So, that's how I would say you have to approach learning compression.

It's actually experimenting with it. And the one thing I would say that could

take it beyond this kind of in your learning and learning to hear and utilize

these devices is. Perform your instrument while compressing

it. Or even talk into the compressor.

I find it's very interesting as you're performing your instrument, you're

feeling how the compressor is responding to you -- so as you play louder, the

compressor pushes it down, as you play quieter, the compressor opens back up,

and as you're performing into it you're really going to get a sense of how that

compressor, how that dynamic processor is related and interacting with your

performance naturally. So those are the major dynamics

processors. We have gates and limiters and

compressors. We've looked at the extremes, in this

course here, so that we can understand how these function.

It's going to be up to you to take it to a more musical usage in the future, but

the only way you're going to get there is if you know how they function and you

know. What the extreme sounds like, cause then

you'll be able to back that knowledge down into a musical range.

I'd like you to go to your DAW and experiment with this, try to open up drum

groove and compress it. And then as you're listening to records

from now on try to recognize the sound of compression.

It's quite obvious once you get used to hearing it.

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