The best professional mixing engineers are typically also the best professional lazy people. Instead of having to manually ride faders constantly engineers decades ago invented an automatic volume automation tool and called it a compressor.
In this tutorial, Fab Dupont explains the most essential controls on this powerful and often confusing studio staple.
Fab explains what each knob does and gives you easy-to-remember tips that will simplify the process of dialing in your own compressor settings.
Compressor controls covered:
Threshold
Ratio
Make-up gain
Attack
Release
Learn how to set your compressor to gently kiss the peaks or rudely slap around the input signal with Fab's detailed explanations and clear audio examples.
Compression has a signature sound to it - once you hear it and understand exactly what's going on you can truly be in control over the tone, level and speed of your tracks.
00:00:07 Good morning children!
Today we're going to talk about
fundamental compression settings.
00:00:12 We could have decided to get
a collective root canal without anesthesia
but our collective dentists are
busy today,
so we're gonna stick with
the compression thing instead.
00:00:19 The first thing I'd like to do
is redefine what a compressor is.
00:00:23 A compressor is
an automated fader, or dimmer
that does this
when your signal gets too loud.
00:00:28 It does this again
when your signal gets too loud again,
and it does this often
when your signal gets too loud often.
00:00:35 That's the whole point of having
a machine doing it for you, a compressor,
instead of doing it by hand.
00:00:40 This is a business for lazy people.
00:00:43 This is essentially a discussion
about gain reduction, you know...
00:00:46 lowering levels like that.
00:00:48 You've seen it
represented in different ways.
00:00:50 If you look at the built-in
Digi compressor for example...
00:00:56 You see a red thing going down,
just like my fader. Fair enough.
00:00:59 In the past, on analog devices,
you may have seen it like this,
a needle going from right to left.
00:01:08 That makes sense.
00:01:09 And then, some twisted souls decided
that this would be ok too...
00:01:15 A needle going from left to right,
or up, to show gain reduction.
00:01:19 Some people just like to confuse
other people. But not us!
Today, we're gonna discuss
gain reduction, compressors,
and the settings that go with.
00:01:27 The first setting I'd like to discuss
is threshold.
00:01:30 How does one think about threshold?
I like to think of it as a pointer
towards the part of the signal
that I want to process.
It's a top/down system.
00:01:38 You start high, and then you lower
the bar, and when you start hitting
the louder parts of the signal,
you start to process.
00:01:44 The more you go down,
the more of the signal you process.
00:01:46 This is pretty simple, let me show you.
00:01:48 This is a cajón. A cajón is
a traditional percussion instrument
from an exotic place, meaning
not the USA. It sounds like this.
00:02:00 You noticed there's
a "Tchugga, Tchugga, Tchugga" going,
and then there's a "Plak! Plak!" going.
00:02:04 As you can see on the waveform,
the "Plak! Plak!" is much louder
than the "Tchugga, Tchugga".
00:02:09 Let's say I want to take care
of the "Plak! Plak!"
but not the "Tchugga, Tchugga."
I'm gonna lower my threshold
so that the bar hits the "Plaks",
but not the "Tchugga, Tchugga!"
And it sounds like this.
00:02:30 Now, every time the "Plak!" happens,
because of where I put my threshold,
some gain reduction's happening.
The difference in sound is staggering.
00:02:37 This is flat...
00:02:43 And this is with the compression.
00:02:49 Again, without...
00:02:56 With...
00:03:03 Only the loud part of the signals
are compressed.
00:03:06 If I want to be a hooligan
and go lower,
all I have to do is lower the threshold
and everything is gonna get compressed,
and it sounds like this...
00:03:23 Definitely for hooligans.
So let's bring it back up
to something slightly more reasonable.
Ever so slightly more reasonable...
00:03:33 Fair enough!
So now we know which part of the signal
we want to compress
using the threshold control.
00:03:39 The next question is
how much do you want to compress it,
and that's the job
for the ratio control.
00:03:44 The ratio control determines
the amount of gain reduction.
00:03:47 Meaning, it controls how far down
your automated fader is gonna go.
00:03:51 This involves some maths, which will
bring you back to your High school days
only without the sweetheart,
or the popularity contents.
00:03:58 It's a division, it's a ratio.
00:03:59 So for example,
if you have a 2:1 ratio,
it means that any signal
over the threshold
will get divided by 2 level-wise.
00:04:07 4:1 ratio... divided by 4!
8:1 ratio? You guessed it, divided by 8.
00:04:14 What happens if you have
a 2 dB overshoot
on a 8:1 ratio?
You guessed it, a 0.25 dB output,
which means your fader has to go
down 1.75 dB. That's how it works.
00:04:32 The good news is you do not need
to know any of this
to have a hit on the radio.
Isn't that wonderful?
Let's listen to what it sounds like.
00:04:39 A 1:1 ratio means nothing is gonna
happen. This is the signal.
00:04:43 You're gonna see me raise the ratio.
You're gonna hear the same signal
getting processed more and more.
00:04:49 I'm not processing
more of the signal,
I'm processing the same signal
more and more.
00:04:54 That's very different. Check it out.
00:05:16 The "Plak!" gets nuked, and
the "Tchugga, Tchugga" gets untouched.
00:05:19 The "Plak!" gets more and more nuked.
00:05:21 There's something
that's very important to know.
00:05:23 Most of the compression happens
between 2:1 and 8:1 ratios.
00:05:28 When you go over 8:1 or 10:1,
you start to have less effect.
00:05:32 Check it out! This is 2:1.
00:05:37 This is 8:1.
00:05:41 And this is 50:1.
00:05:45 There's much more of a difference
between 2:1 and 8:1
than between 8:1 and 50:1. There's
nothing between 50:1 and infinity.
00:05:52 Check it out!
It's the same.
00:06:00 It's good to keep in mind that if you
find yourself playing with the ratio
between 20:1 and 100:1
and still not getting what you need,
you're probably
fiddling with the wrong setting.
00:06:10 Now we know about threshold and ratio,
let's talk about gain,
sometimes known as make-up gain.
00:06:16 Does this mean
your compressor is wearing make-up?
Absolutely not!
It's not that kind of girl.
00:06:21 Let me show you what it means.
Remember my cajón?
I was just kind of kissing
the "Plak!" part,
but the "Tchugga, Tchugga"
stayed as is, right?
And it felt pretty good!
Let's listen to it.
00:06:31 First, without the compressor.
00:06:38 And then with.
00:06:44 It basically feels the same, right?
Level-wise.
00:06:46 But what if I squish it?
This is without...
00:06:55 And with...
00:07:01 Obviously it's much softer.
Of course it is softer!
If you're just dealing with the peaks,
the compressor is just
doing this really quickly.
00:07:09 The overall level doesn't
feel different.
00:07:11 But if you're squishing it really hard,
you're really bringing the fader down,
and it's down there.
00:07:16 You can't really tell what's going on,
because you're listening to something
maybe 10, or 15 dBs softer
than the original.
00:07:21 The human brain is wired
to like louder signals better, always.
00:07:25 If you're compressing something a lot,
it's gonna bring the level down a lot,
like we saw.
00:07:30 For you to be able to compare
original and compressed signals,
you need gain to bring the compressed
signal back up to the original level,
so you can truly compare the difference
in tone, and not just in level.
00:07:40 That's what the gain button is for.
00:07:43 In the case of the cajón,
it would do something like this.
00:07:46 This is my raw signal.
00:07:49 The compressed signal...
00:08:06 So now, I can really tell
what I'm doing to my signal,
I'm being rude!
Which brings me to my next point!
Here's what's going on.
00:08:13 My compressor is bringing
the high level down.
00:08:17 And then the gain is bringing
the whole thing up.
00:08:20 As a result, the low levels, which
were low, are now being brought up.
00:08:23 I'm bringing up
everything that's low down there.
00:08:26 What's there? Well, noise, garbage,
bleed from other instruments...
00:08:30 Let me show you.
00:08:31 Here's another example, check it out!
What kind of mic is that?
Well that's a snare mic!
If you turn the compression off,
it sounds like this...
00:08:52 Here's what's happening.
00:08:54 I'm super compressing everything.
So I'm bringing the snare down.
00:08:57 But I'm raising the gain
by 18 dBs and change.
00:09:00 So I'm bringing all the bleed
from the other instruments up,
so it's being compacted, or compressed.
00:09:05 Now, that's a good thing,
you can make cool sounds.
00:09:08 But say you have
a snare drum that's recorded
that has quite a bit of hi-hat in it.
What's gonna happen?
The difference between the snare
and the hi-hat is gonna go "Pfff..."
and you're gonna have as much
hi-hat as snare in your snare mic.
00:09:19 You know how that feels.
That gives you a nose bleed.
00:09:22 That sucks. You don't want to go there.
00:09:24 You have to be careful what you do with
your compressor and your make-up gain.
00:09:27 That's the art of it.
00:09:29 One last consideration for
the gain button is that of gain staging.
00:09:32 It is great to strive and keep levels
consistent pre and post compression,
pre and post any processing, really.
It's great for comparison,
but it is also great to hit
your hardware, your plug-ins,
your converters in their sweet spot,
just like you saw in
the Recording Level video, did you not?
So we have threshold, we have ratio,
we have gain, we're gonna
move on to attack and release.
00:09:56 Or should I say
the almighty attack and release...
00:10:00 Attack and release,
sometimes labeled time constants,
are the two settings that I see
confuse people the most.
00:10:06 Probably in part because most
compressors are grossly mislabeled.
00:10:09 They label everything as time,
where it should be labeled as speed.
00:10:12 No, really, trust me!
That's the way it is.
00:10:15 That's a speed control.
00:10:16 What they mean is
dB per second settings.
00:10:20 But we don't want to go there, because
that brings us back to High school
and all we want is a hit on the radio.
Let me show you how it really works.
00:10:27 You could think of it this way.
There are two parties involved:
your brain, which listens to
the original signal, the music,
and decides how much
gain reduction it wants,
and your finger, that's supposed to
achieve that gain reduction on the fader.
00:10:40 Now there's a communication link
between your brain and your finger.
00:10:44 Say you just had a lot of coffee,
your finger is very alert
and able to catch up with the gain
reduction orders from your brain.
00:10:50 That's a fast attack and release.
00:10:52 Say you went out last night and drank
too much, you're hung over and sluggish.
00:10:56 Your finger can't keep up with the gain
reduction orders from your brain,
it's behind.
That's a slow attack and release.
00:11:03 The beauty of this is you could have
coffee on the way down
and hangover on the way up,
or hangover on the way down,
and coffee on the way up,
meaning fast attack, slow release,
or slow attack, fast release.
00:11:15 Wouldn't it be wonderful
to have that in real life?
Now let's look at practical examples.
00:11:20 Let's focus on the attack control.
00:11:22 Here's a standard snare,
with no compression.
00:11:31 I'm gonna turn on the compressor.
My threshold is at -24 dB...
00:11:35 with a ratio of 3:1.
00:11:37 I'm opening the attack
all the way up, 300 ms.
00:11:39 This is what it sounds like...
00:11:46 Now the threshold is really low
and the ratio is appropriate,
why is nothing happening?
Well... this is what's happening.
00:11:53 Since the attack is so slow,
the compressor is not fast enough
to reach for the fader in time
and bring it down, so basically,
this is what's happening.
00:12:02 Oh! Sorry!
Oh! Sorry.
00:12:04 Oh!
My bad...
00:12:07 Let's do it again!
I'm too slow!
Now as you speed up the attack,
stuff happens. Check it out!
What's happening is that,
as I'm speeding up the attack,
my finger is getting faster and faster
at following the gain reduction orders
form my brain.
00:12:29 I'm having coffee on the way down.
00:12:31 Is my finger doing exactly
what my brain wants?
Maybe, maybe not. That depends
a lot on the source signal.
00:12:37 But something is starting to happen,
and that's what matters.
00:12:41 As you speed up the attack further,
you get into transient control.
00:12:44 Let me show you.
00:12:46 Here's the same snare. I'm gonna start
with an attack of 4.2 ms,
which means absolutely nothing!
Let's call it "Speed 4.2",
and then I'm gonna speed it up.
00:13:08 The transient gets nuked.
My finger is now fast
that it can grab the fader
and bring it down instantly,
killing the top of the snare sound,
taking all the punch away.
00:13:17 Is that a good thing, or a bad thing?
That's a different discussion!
Let's talk about release.
00:13:22 The release phase of a compression
cycle happens when your brain
tells your finger
to not compress as much.
00:13:27 Why would your brain do that?
While your brain is listening to
the input signal,
if the input signal is not as loud,
you don't need to compress as much,
and it tells your finger:
"Yo! That's too much! Go back up."
The release control says
how fast that should happen.
00:13:42 Here's our snare.
As you can see in the waveform,
we have a sharp transient,
a loud transient.
00:13:47 And then we have a quieter tail.
00:13:50 In this case,
I'm using a fast attack and release.
00:13:54 What this is gonna do is that
the transient and the body of the snare
are gonna be at the same level.
And it sounds like this.
00:14:04 On a snare
that really sounded like this.
00:14:09 Again, with.
00:14:14 That's a fast attack and release.
00:14:16 That means that now, my transient
and my tail are at the same level,
and give this sound.
What happens if I lengthen the release?
This is what happens...
00:14:31 As a reminder, the snare sounds
like this uncompressed.
00:14:38 With the compression...
00:14:44 What happens is this: the first snare
hits, and the attack is so fast
that the gain reduction fader
goes down here.
00:14:49 But then the release is so slow,
that the gain reduction fader does not
have time to go back up
before the next snare hits
and tells it to stay there.
00:14:58 It's actually going back up,
but so slowly that you can't hear it.
00:15:01 Now why does it sound the same?
It sounds the same because...
Imagine this...
00:15:06 Say this is my gain reduction fader,
and this is my Master.
00:15:10 The red is the gain reduction,
the green is the Master.
00:15:13 What is the difference between having
no gain reduction
and the Master down here,
or full gain reduction,
and the Master up here?
Zilch!
Side note number 1.
00:15:24 When a compressor manufacturer
sells us on the fact
that his box can do 25 dBs
of totally transparent compression,
it means again: zilch!
The question is:
does it do it in static compression,
or can it do it in dynamic compression,
meaning the fader is moving?
If it's only static compression,
we might as well use a fader.
00:15:43 Side note number 2.
00:15:45 Why don't we use really fast
attack and release times
and enjoy a perfect link between
our brains and our gain reduction faders?
Because there are
problems associated with that.
00:15:54 We just saw the transient problem,
here's another one.
00:15:58 Some instruments like bass drums
and basses with long wavelengths
can distort really quickly
with fast attack and release times.
00:16:05 The reason for this,
and I'm gonna simplify drastically,
is that the compressor gets confused
and reads the oscillation
of the waveform as volume changes
and tries to ride the waveform itself.
00:16:16 In English, it don't sound so good.
Let me show you.
00:16:19 Here's a bass recording.
00:16:26 It sounds good.
Now I'm gonna quicken the attack.
00:16:37 Distortion comes in.
00:16:39 If I return the attack where it was
and quicken the release, this happens.
00:16:50 With the two of them,
it sounds like this.
00:16:58 If you're in this situation,
all you have to do is slow down
the attack, or the release, or both.
Season to taste.
00:17:05 Side note number 3.
00:17:09 A lot of people think that
attack and release phases
happen only when the signal
crosses the threshold.
00:17:16 On the way up for attack,
and down for release.
00:17:19 That ain't true!
It is true that the first attack phase
happens the first time
that the signal goes
above the threshold.
00:17:25 But after that, it's independent.
Let me show you.
00:17:29 This is what happens.
00:17:30 As long as I'm above the threshold,
I'm compressing.
00:17:33 Meaning my gain reduction fader
has movement.
00:17:36 My brain still monitors
the source signal.
00:17:38 If there are differences in level
in the source signal,
then my brain is gonna tell
my finger to react.
00:17:44 If it gets louder, it's gonna say:
compress more.
00:17:46 If it gets softer, it's gonna say:
compress less.
00:17:49 The reality is that when I compress
more, there's an attack phase,
and if I compress less,
there's a release phase.
00:17:55 Of course, none of that happens
in static compression,
but we don't do static compression,
we use faders.
00:18:00 Chew on that!
In summary, we've looked
at five parameters.
00:18:04 Threshold lets you decide which
part of the signal you want to process.
00:18:09 Ratio lets you decide
how much you want to process
that part of the signal
you just singled out.
00:18:14 Make-up gain lets you compensate
for the loss in volume
from heavy compression.
00:18:19 Attack and release are gonna decide
how fast or how slow
you're gonna respond
to the changes in gain reduction.
00:18:25 Understanding and mastering
those five parameters
will let you get away with murder.
00:18:30 And I can hear you think from here,
there are other parameters
like Soft knee,
Peak or RMS detection,
Automatic attack and release,
Hold, Automatic gain...
We know that!
We will cover those other parameters
in a different video.
00:18:43 Until then, go squish something!
Et voilà!
Once logged in, you will be able to read all the transcripts jump around in the video.
Fab Dupont is a Grammy winning NYC based record producer, mixing/mastering engineer and co-founder of pureMix.net.
Fab has been playing, writing, producing and mixing music both live and in studios all over the world. He's worked in cities like Paris, Boston, Brussels, Stockholm, London and New York just to name a few.
He has his own studio called FLUX Studios in the East Village of New York City.
Fab has been nominated for Grammys 6 times, including two Latin Grammys and has received many other accolades around the world, including Victoires de la Musique, South African Music awards, Pan African Music Awards and US independent music awards.
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By far the best tutorial on this topic I've seen so far!
erdincbashan
2017 May 31
Isn't Fab a great teacher/mentor? Thank you monsieur!
Jonathanbminor
2017 Jan 19
Thank you Fab !! I truly appreciate the lesson !!!
soundspace2001
2016 Dec 06
Very funny und lively and well explainded - thx!
davidromero
2016 Nov 22
I have a good understanding of compressor functions, but I watched this anyway. I've seen/read quite a few videos/articles about compressors and this is the best explanation
Bravo Fab!
FacPhoto
2015 Jun 16
Haha Fab, I love this video, it´s hilarious =) Thanks
drbeckel
2015 Apr 28
For the French mathematicians:
Gain reduction in dB = OS - [OS x R] where R is the compression ratio 1/n and OS is overshoot in dB
GR = OS - [OS x 1/n] where n is the denominator in the compression ratio
If n = 1, then GR = OS - [OS x 1/1] = OS - [OS x 1] = OS - OS = 0, ie., no reduction.
If n gets so VERY big as to approach infinity, then the ratio 1/d becomes VERY small and approaches 0 and therefore
GR = OS - [OS x 0] = OS - 0 = OS, ie., 100% reduction in the overshoot which is what a limiter does.
bdunn315
2015 Apr 08
Fantastic video Fab. Even for those who have been using compressors for a while, it's great to back up for a moment and really get an understanding of what is going on...and you have done a marvelous job once again laying things out in a way that provokes methodical thought. Thank you. I've truly deepened by knowledge and changed the way I approach compressors.
GuitarLegend
2014 Dec 06
I don't mind spending money on an educational video that confirms what I already know but I thought this one was so basic that it could have been a freebie...
eike_ebbel
2014 Dec 04
I would love watching a video about 2-bus-compression. I know how
to handle comp settings on individual tracks but the last comp in chain makes
me struggle sometimes especially when it comes to finding the right attack and release
settings. Would be cool watching Fab do this special task in a special video.
msloan
2014 Nov 01
FAB....great job! excellent video!
jeromewauk
2014 Oct 30
Absolutely BRILLIANT explanation of compression parameters. Thanks Fab!!!!
rialcorrales
2014 Oct 29
One of the best explainations about compression I've seen. Good job Fab!!!
Fabulous Fab
2014 Oct 29
@emey: the french are coming, the french are coming!
emeyer
2014 Oct 25
Thank you very much, another great tutoriel on the audio tools, but will you put online a French version, because it is too much compressed for me in English ;-)
