I have another tutorial video for you. This video is the last in a series of videos that Urban
Francis and I put together, as a techno production project for a track called Hijack.
The track was produced in Ableton Live, and we have all
of our Ableton project files available as a free download from Dropbox.
In this specific video, we wanted to explain what was
going on with the Side-chain compression.
Eventually, the two of us are going to do a very detailed and complex
set of tutorials about compression and side-chaining. They’re very complicated and moderately
advanced topics, and they take a little while to learn to do properly. However, because we have some side-chaining
happening in the Hijack project, we decided that it would be smart to give a
brief overview, so any producers who are moderately familiar with Ableton would
understand exactly what we’re doing here.
Here's a link to the video:
If you don’t understand what compression is, let’s start
there, even though it’s a pretty complex topic.
I tried to do an explanation in my Mastering & Marketing Your DJ Mix video
on YouTube, starting at the 21 minute mark. It’s worth a watch, because of the graphic
visuals. However, let me also try to
explain it here.
A lot of people,
when they hear about compression, they get the idea that compression makes
things louder. That’s incorrect. Compression by itself does not raise the
level of an audio signal. There are
several different settings in a compressor, but the main ones are this:
Threshold Value – this is the signal level above which
audio is being affected.
Ratio – tells how much the portion of the audio that is
above the threshold is getting squished.
Now obviously, if the audio is getting squished, then the
audio is getting pushed down from its original volume to a lower volume. So why, when people talk about compression,
do 99% of them think that the audio is getting louder? That’s a great question, and it’s something
that a lot of people don’t understand properly.
First, you need to understand that compression BY ITSELF does not make
the volume louder, it reduces the volume.
Now, let’s be honest – in the fight for volume to gain
prominence in the listening space, very few people want to reduce the volume of
their productions. So that’s where
another setting commonly associated with compression comes into play. That setting is the make-up gain.
After compression is done, if a producer applies make-up
gain to the compressed audio, it brings the volume back up. A producer may set the make-up gain to the
exact amount to bring the peak of the volume back up to where it was before the
audio was compressed. Sounds like a
rather useless practice, doesn’t it?
Drop the volume, then raise the volume.
But the key thing is that when the volume is compressed,
it is NOT dropped in a linear manner.
Louder parts are dropped more than quieter parts. Hence the reason that I said that the audio
gets squished. Therefore, the audio now
has a narrower dynamic range than before.
The peaks and valleys in the amplitude are not as significant; the
changes from the loud parts to the soft parts are less significant.
Since the peak of the volume is unchanged from the
original, once the makeup gain was applied, and since the dynamic range from
loudest to softest is reduced, this means that the AVERAGE volume of the
processed audio is louder. And that’s
the source of the misconception that compressed audio is always louder. Compressed audio definitely has a narrower
dynamic range. If it is louder, that is
only because makeup gain has also been applied.
Side-chaining
Moving on to Side-chaining, the way that side-chaining
works, is that you’re taking a signal from somewhere else, and you’re analyzing
that signal, and you’re using the analysis of the side-chain signal to control
the compressor’s actions on whatever other audio is being compressed. So in other word’s, the compressor’s actions
are being dictated by the energy of the side-chain signal (side-chain audio
source) that’s being fed into the compressor.
Remember that the signal that’s being fed into the
compressor (the side-chain signal) may have nothing at all to do with the audio
that you’re processing. And also,
remember that you don’t have to have a signal being fed into the
side-chain. If you don’t have a
side-chain signal, the compressor just works at a steady set of values while it’s
processing audio. Essentially, a
side-chain compressor without a side-chain signal is just … a regular
compressor.
Ok, so imagine this.
Let’s pretend that the signal that is coming in to the side-chain input
of the compressor is some sort of signal that is steady and repeating. High energy/amplitude (lots of signal)
alternating with low energy/amplitude (quiet).
A good example might be a repeating kick drum. If you keep hitting a kick drum in a steady
pattern regularly, then the “signal” (amplitude) is essentially a constantly
repeating on/off/on/off/on/off/on/off pattern.
If this signal is what is controlling the compressor, then you’re basically
turning the compressor on/off/on/off/on/off/on/off in the same timing and
pattern.
Many producers DO use a kick drum as a side-chain signal,
so that a side-chain compressor keeps turning on and off in time with the kick
drum. The compressor may be processing
just about anything else while it keeps turning on and off. Maybe it’s processing a synth line. Maybe it’s processing a background pad. Doesn’t matter. It’s compressing some sort of audio, and it’s
turning on and off in time with the beating of the kick drum, since the kick
drum is being used as the side-chain signal.
A producer can use the kick drum from the track they’re
working on, as the side-chain. But they
don’t have to. They could use a
different kick drum track as the signal.
And that other kick drum which is being used as a side-chain signal to
the compressor does NOT necessarily have to be audible to listeners of the
track. So a producer could easily have
two kick drum tracks in their song: one
that is audible that the audience can hear, and a second one that is not
audible to listeners, but which is being used as a side-chain signal.
Why bother using two different kicks? Maybe the producer wants a signal with a fast
release for the side-chain (to turn the compressor off quickly), but doesn’t
want the listeners to hear a kick that has a fast release. Or maybe the muted side-chain kick needs to
act as a side-chain signal during parts of the song where there is no kick drum
playing.
If a producer brings an extra kick drum (or any other
type of instrument or midi notes) into a side-chain compressor, but that
audio/midi side-chain signal is not audible as part of the project, the
side-chain audio signal is called a ghost signal, or ghost notes.
Using a side-chain to turn your compressor on and off
allows you to compress audio when needed, to allow for a different part to
shine through a mix, but does not compress the audio at other times. This gives the producer a lot of
flexibility. It’s much better than if
the producer’s only option was to permanently decrease the volume of other
parts of the mix.
An advantage of using ghost notes or a muted side-chain
signal is that you can have it turn the compressor on and off in any pattern or
timing that’s convenient to you.
An advantage of using a regular audio source within the
song (one that the listeners hear) as a side-chain signal to affect another
track is that the timing may be perfect for your needs. For example, if you need a kick drum to cut
through a synth line, you can play the audio of the kick, and you can
simultaneously route that auto into the side-chain of a compressor that cuts
the volume of the synth, allowing the audio version of the kick to cut through
the mix.
By the way, if you want to see the project that we used as the basis for this tutorial, here's the music video (yes, the full project files for this track are available as a free Ableton or stems download):
I'm Jonathan Clark, known online as DJ Bolivia. Do you want to learn more about DJ'ing and music production? If so, visit:
If you happen to enjoy techno tracks, most of my tracks are available as free downloads from this link:
Thanks so much for visit, and for your support! I really appreciate the fan base that I've been able to build up over the years.
Also, if you want to visit any of my other sites, here are a few links:
YouTube: youtube.com/djbolivia
SoundCloud: soundcloud.com/djbolivia
Blogger: djbolivia.blogspot.com
Main Site: www.djbolivia.ca
