Monday, March 8, 2010

Compression & Side Chain Compression in Ableton Live

A producers secret weapon. Compression. Something that is very confusing to a lot of people, but if understood, can be the best tool in the bag. Today we are going to run through compression a little bit, and a bit of side-chain compression. We will talk a little bit about the parameters within ableton, and some tricks on how to use them.

Here is a picture of a compressor (actually being side-chained on my bass) within my track.

The most important thing to realize when you are dealing with a compressor is that you are dealing with VOLUME. Basically, you are telling it to lower the signal once a certain db level has been reached.

Lets talk about each part of abletons compressor.

First, and most importantly is the THRESHOLD. Threshold is the level (in db) in which must be reached before the compressor will kick in. In my picture, its -26.7db. So the compressor will not kick in unless that level has been reach. The lower you go, the easier it is for the compressor to take affect.

The output is your final output signal. (you can now raise it a bit since its been reduced)

The attack is how long it takes the compressor to fully kick in once the threshold has been reached. With the attack setting at its far left, it will attack very hard. For a softer attack, move the knob to the right.

The release is how long it stays activated. For a harder sound (quick release), keep it left...softer sound (longer release), to the right.

GR - The little meter the the right of the graph means GAIN reduction, and is how much gain is being reduced.

Ratio is how much the compressor will lower the volume once the threshold is exceeded. With a low ratio like 5:1, for every 5 decibels that pass the threshold level, only ONE will actually pass. So 10:1 would be even harder....letting only 1 pass for every 10. After this amount, you are basically using a LIMITER which is the same concept, much much more dramatic. Try lower ratios unless you are looking for a REALLY big change. I usually stay anywhere from 3-6.

PEAK & RMS - This is the behavior of the threshold.

Peak mode is used for drums and percussion, and reacts very quickly to sudden volume changes.

RMS mode calculates the average volume shifts and adapts accordingly. Good for pads, vocals, and if you are using it on a master mix.

Opto uses a non-linear release curve, and the release becomes slower as the gain gets close to 0. I dont use this much.

Knee - Having a hard knee (more looking like a hard angle) makes the compressor engage more quickly once the threshold is reached. A soft knee lets the compressor gradually kick in as its about to reach the threshold. I like a little bit of a softer knee, but again, it all depends on what sound you are going for. You would find a hard knee useful when compressing drums and percussion, so not to lose the attack sound of it.

Lookahead is letting ableton look ahead at your audio, to predetermine things before it comes in. I NEVER use this, I feel like its basically useless.

So whats all this shit mean! Just as confused as before. Here is a few nice tips for starting-

1. Drop your threshold down a bit. Lift the attack and release up a little bit. Put the ratio at 3:1 to 6:1.

2. Stay in RMS or PEAK MODE. Dont mess with anything else.

3. Move your threashold, output, release, & attack around until you get a nice sound.

The compressor can be deep in its math, but, its all about your ears. Those are the main parameters. Everything else is so technical, that it comes with experience. But, take the info I gave you and apply it to the sound you are looking for.

OK...NOW, the best part....SIDE CHAIN COMPRESSION! One of the best tricks of good producers. What you are doing with side-chain compression is having a different audio element active the compressor (like a kick drum). Side-chaining is mostly used for bass, but can be used on pads, melodies, or virtually anything to get a nice PUMPING SOUND.

First thing you wanna do is drop in a kick track, either an audio, or midi file. Loop it. Now, in this tutorial, we will side-chain the bass. So, make an 2nd audio track with a bass loop in it. Toss in a compressor, then click the little DOWN TRIANGLE next to the word compressor in the effects rack to open up the side-chain. Now, you need to select your input as your kick track like this -

I usually like to set my gain to 0 and my dry/wet all the way up to 100% to get the full effect. You can change these if you like, but to get full compression, set it to those settings.

If you want a certain frequency of the kick to activate the compression, us the EQ to determine that...but you are now getting deep into compression, and this is not really necessary unless your a crazy producer looking for some WAY particular sound. I never use it.

Now, if you play the 2 tracks together, (as long as you have the threshold down a bit) you should be able to hear the the BASS volume is cutting when the kick is kicking. This is nice because that means your kick drum will always get the priority in volume, and the 2nd sound (bass in this case) wont clash. Play around with the attack, release, & threshold to get a nice sound.

Another nice trick to get that NICE pumping sound to different sounds, is to toss this on other tracks in the mix...even when the kick is muted. Go ahead and leave the kick running, and mute the track. You can still hear the kick activating the compressor, but the kick is not there. This can make for a nice effect during build ups or breakdowns. If you want to get a REALLY REALLY strong pumping effect, drop that threashold ALL THE WAY DOWN. It will totally cut the volume when the kick KICKS...making the other sounds PUMP! Use your envelopes to turn on or off the kick track within compose view when composing. You can also use your envelopes to turn on or off the compressor when you dont want to use it either. This is handy when using it in tracks other than bass.

Side-chaining can be used in so many different ways...but remember the most important this order - threshold, ratio, attack, release...and finally, OUTPUT. Get that volume sounding nice within the mix with the output.

Well thats about it for compression. I would go into detail more, but I also need to learn more about compression. It is a deep and complicated effect that a producer must study to get that PERFECT pumping sound...especially out of club speakers.



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