understanding the compressor threshold

[five_magics]

Hi all,
In the example below, I have set my threshold to -27 dB. As you can se with these extreme settings, (smallest attack time and infinite ratio), my compressor is supposed to be able to attenuate my signal to meet the threshold.
Yet my output signal peaks at -18 db on my fader ? I would say it should peek at -27dB
How come ? Is it that the compressor natural lets some level through at very low thresholds ?
Many thanks...




The difference is even more noticeable when the compressor is in RMS mode. I Guess this is just how a compressor behaves.

[Stromkraft]

I Guess this is just how a compressor behaves.

More or less, yes. The threshold is supposedly the level where the compressor starts to have an effect. The ratio determines how much attenuation is applied when the threshold is reached.

Here's a nice article on Compression in Sound On Sound:

[Da hand]

Hi all,
In the example below, I have set my threshold to -27 dB. As you can se with these extreme settings, (smallest attack time and infinite ratio), my compressor is supposed to be able to attenuate my signal to meet the threshold.
Yet my output signal peaks at -18 db on my fader ? I would say it should peek at -27dB
How come ? Is it that the compressor natural lets some level through at very low thresholds ?
Many thanks...




The difference is even more noticeable when the compressor is in RMS mode. I Guess this is just how a compressor behaves.

You are mixing up a Limiter and a Compressor. A Limiter is a special case of a compressor where the ratio is very high and in most software the ratio is infinite, which makes the threshold = the output peaks.

A regular compressor is nowhere near that, which is what you want in the case of regular compression

[fishmonkey]

it's very important to understand that when a compressor changes the signal levels, it inevitably changes the nature of the signal as well.

this is the best explanation of how compressors work that i have read so far:

http://www.attackmagazine.com/features/ ... mpression/

and the best explanation of how to set a compressor i have read is in this book:

http://mixingwithyourmind.com/

[Stromkraft]

it's very important to understand that when a compressor changes the signal levels, it inevitably changes the nature of the signal as well.

The latter usually being why I use compressors. The dynamics comes as a (mostly) positive and naturally inherent part of the deal.