Take the 2-minute tour ×
Sound Design Stack Exchange is a question and answer site for sound engineers, producers, editors, and enthusiasts. It's 100% free, no registration required.

I've heard mention of side chaining or side chain compression in reference to electronic music (specifically Daft Punk). What is it?

share|improve this question
add comment

migrated from video.stackexchange.com Feb 13 at 5:13

This question came from our site for engineers, producers, editors, and enthusiasts spanning the fields of video, and media creation.

2 Answers

With standard compression, the level of the input is used to control the compression. So, when you have loud levels on the input, the compressor works with the input signal and knocks them down, sending them to the output.

Side chain compression has two inputs. One is the signal to be processed, and the other to control the compression. You hear it a lot in electronic music where the kicks come in and everything else ducks out of the way and comes right back after the kick.

So with side chain compression, when there is a loud level on the side chain input, the levels of the regular input signal are reduced.

Side Chain Compression Block Diagram

http://en.wikipedia.org/wiki/Dynamic_range_compression#Side-chaining

share|improve this answer
add comment

Brad's schema is correct.

Additionally, using the side-chain gives you an important feature: it allows you to filter the input signal separately, before it is fed to the compressor.
Using most commonly hi- & low-pass filters, you can say:

I want to compress the full signal, but only when the threshold is surpassed in the range 20 Hz - 200 Hz

This way when the signal has transients outside this frequency range, the compressor doesn't hear these and doesn't react.

It's a side-chain, because it's still the complete signal that gets compressed and sent out.

  • To check which frequencies you're using as side-chain input, some compressors have a "Side-chain listen" button. If you push this, you send the side-chain signal straight to the output.

  • Next to compressors, most gates have this same feature:

I want the gate on my Kickdrum only to open when the threshold is surpassed in the range 20 Hz - 200 Hz

This way, the sound of e.g. the snare drum doesn't trigger the gate.

share|improve this answer
3  
You guys should put addendums to posts as comments. This enhances Brad's answer, but doesn't stand alone as a complete answer to the question. –  Ian C. Dec 15 '10 at 15:12
    
@Ian: I totally agree. I tried first, but what I wanted to explain was a bit too big for the comment field. (And I don't have enough reputation to edit answers) –  jan Dec 15 '10 at 16:30
    
you can comment multiple times. And you can always let a moderator know if you need an edit (or ask more questions to gain rep points!). –  Ian C. Dec 15 '10 at 18:53
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.