Audio Compressors explained #1 - functions


Uploaded by wickiemedia on 11.11.2011

Transcript:
Welcome to his first season of audio tutorials that im giving here on youtube.
In this first season we're looking at dynamic processors and in
this episode were looking at compressors.
Compressors are being used by audio recording studios through out the world
as a tool
to shape the dynamics of an audio-recording.
Therefore it could be categorized as a dynamic processor or dynamic effect.
Normally compressors are being used as an insert-effect,
and that means it will just affect one sound; on the channel that's being inserted on.
So for example a compressor could be inserted into a vocal-track.
Whereas the vocalist would get too loud
the compressor would automatically reduce to volume of that vocal track.
Lets take a look at a compressor's basic overview.
A compressor reduces the volume of an audio track, just like you would do with the fader on a mixing console,
but the compressor does this is a lot faster than you would be able to do manually.
The basic idea of a compressor is that you set the ´threshold´.
When the level of your audio signal reaches that threshold, and gets over it,
the compressor actually starts working and starts compressing.
The amount of compression that takes place is what you set with the ´ratio´
And that determines the amount of compression above the threshold.
I think you can clearly see that with this animation right here.
so the easiest way to explain what a compressor does is to say that it makes loud sounds softer.
Thats what the traditional compressor does.
So these are the first functions and settings of a compressor.
You start up with the threshold, and make sure that the level peaks over the threshold,
or else the compressor won´t work.
So make sure that you lower the threshold or the compressor doesn't do anything.
And the next step is to set the ratio, and that determines how hard the compressor works.
So Ratio 2:1 (two-to-one) means that for every
two decibels above the threshold only one will be outputted by the compressor.
Ratio 20:1 (twenty to one) means for that for every twenty decibels above the threshold
only one dB will output. So thats is called 'hard compression'. 0:02:04.590,0:02:09.180 If you compare with ratio 2:1, that would be soft compression.
And ratio 1:1 means basically that for every 1dB above the threshold, also 1dB will output.
So that's a neutral position, and you will have no compression at all.
Let's listen to a dynamic vocal track without any compression on it
and then compare that with a track where we actually apply compression on
so can hear the difference.
Here I'm playing an original drumtrack, with no compression on it.
Now compressed with ratio 2:1
Ratio 4:1
Ratio 10:1
And he would keep the Ratio 10:1 but we lower the threshold even more.
As you could hear the sound got a lot softer when we applied the ratio 10:1
Especially when we lowered the threshold.
That is because we've just used the 'threshold' and the 'ratio' setting of this compressor.
And I didn't look at any of the other settings yet.
So what i haven't looked at yet is that we can compensate the amount of
compression or gain-reduction that occurred
by applying makeup-gain or compensational gain.
So here is the original drum-signal.
And here we listen to to compressed drums but with make-up gain.
So we actually compress it with a ratio 10:1 and than we bring up the level
to match the original input level.
What has happened here is that we have reduced the amount of dynamic range.
We made that loud sounds softer, a lot softer, so we brought them closer to the soft sounds,
like the high-hat,
and then we brought up the volume of the overall drums back.
So basically what we did is that we brought the soft sounds and the loud sounds closer together.
And you can really hear it sounds more aggressive this way.
So now we've seen the most basic controls that a compressor has,
that be the threshold, which is the level at which the compressor starts working.
And than the ratio, of how hard the compressor works on signals that need to be compressed.
And then we have the makeup-gain, which compensates for the amount of compression.
There's two other things that are really important of setting up a compressor.
And that is the so-called attack and release time. These are settings which work on an amount of time set in milliseconds.
Some compressors actually offer you an option 'fast-attack' or slow-attack
or auto-release and these things.
But it's always similar to that.
The attack-time of the compressor determines how fast the compressor applies the compression
when the signal gets over the threshold.
Whereas the release actually tells how long it takes for the compressor
to stop compressing when the level jumps below the threshold again.
So that's basically the attack and the release-time. But those are really important in
setting up how fast will the compressor actually work. So if we got a snare drum,
and we set a compressor on it with a really slow attack time,
the compressor will barely or probably not work at all, because it's too slow.
So the attack-time determines how fast the compressor starts to work.
I'm gonna show you an example, so you can hear and see it at the same time.
I'm changing the attack time
as i do that you can really hear the effect on the kick and the snare-drum
especially in the 'punch'.
And that concludes part one of the first tutorial about compression techniques.
In part two I'm really going to look at how to set up a compressor,
and how they're being used. I'm going to look at different compression-techniques
like new york drum-compression, side-chain compression
and all these other types of things. And in part three I'm even gonna compare a lot
of different brands of compressors and really hear the distinct sound of each one.
so I hope you've learned something today. See ya'll in part two and part three.
You should be able to see the links right here.
...And don't forget to subscribe to my channel for a lot more videos!