Compression, The Problem Is..

[thesound]

I never understand this… You set the threshold to a level that you want the compression to start, I have a track which is at, say, +2.1, I set the threshold to 0.0. Nothing. How come?

This thing always winds me up when reading a guide.. "Threshold – how loud the signal has to be before compression is applied."

[Roflcopter]

Hi

always check the article base

http://recording.songstuff.com/article/compression/

[Retrosaurus Rex]

dBs?

Don't get me started on dBs...

[john]

I assume were are working within the analog world as frequencies above 0dB would result in digital distortion.

the article Roflcopter pointed you at should help there is also an article on the compressor by Graeme Young (Prometheus) listed.

Tom is right that the compression is only applied above the threshold frequency at the ratio you set. It's not as simple as that though, as i am sure you have guessed. the other two main controls are the attack and release. The attack dictates how quickly the compression is applied after the threshold is passed and the release is how quickly the compression is removed after the trigger threshold is passed.

if your attack and release are too short you might not notice much, a little too short for the source sound and you will experience an effect called "pumping" where the effect is noticeably switching on and off.

Lastly and most obviously is to make sure that the bypass switch isn't depressed!

[Prometheus]

I assume were are working within the analog world as frequencies above 0dB would result in digital distortion.

the article Roflcopter pointed you at should help there is also an article on the compressor by Graeme Young (Prometheus) listed.

Tom is right that the compression is only applied above the threshold frequency at the ratio you set. It's not as simple as that though, as i am sure you have guessed. the other two main controls are the attack and release. The attack dictates how quickly the compression is applied after the threshold is passed and the release is how quickly the compression is removed after the trigger threshold is passed.

if your attack and release are too short you might not notice much, a little too short for the source sound and you will experience an effect called "pumping" where the effect is noticeably switching on and off.

Lastly and most obviously is to make sure that the bypass switch isn't depressed!

All excellent points John. Speaking of the bypass switch, it can be used to make sure by A-B comparison that the compression settings applied are enhancing the sound and not destroying it.

Here's a nice trick for timing releases, particularly on basso and beats.

Step 1: Take 60,000 as a coefficient, divide it by the tempo of the song in beats per minute. This will give you the number of milliseconds in the demoninator of the time signature, for example in 4 / 4 it would give you the milliseconds per quarter beat.

Step 2: Divide this number by two until it falls between fifty and one hundred.

Step 3: Make this number your release setting.

So, for a 120 bpm song,

60000 / 120 = 500

500 / 2 = 250

250 / 2 = 125

125 / 2 = 62.5

Edited November 29, 2010 by Prometheus