understanding the compressor threshold

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five_magics
Posts: 37
Joined: Wed May 08, 2013 8:31 pm

understanding the compressor threshold

Post by five_magics » Sun Nov 08, 2015 1:47 am

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 :roll:
How come ? Is it that the compressor natural lets some level through at very low thresholds ?
Many thanks...

Image
Image

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

Stromkraft
Posts: 7033
Joined: Wed Jun 25, 2014 11:34 am

Re: understanding the compressor threshold

Post by Stromkraft » Sun Nov 08, 2015 2:52 am

five_magics wrote: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:
Make some music!

Da hand
Posts: 1649
Joined: Sat Jan 18, 2003 8:38 pm
Location: Montreal, Canada

Re: understanding the compressor threshold

Post by Da hand » Sun Nov 08, 2015 3:53 am

five_magics wrote: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 :roll:
How come ? Is it that the compressor natural lets some level through at very low thresholds ?
Many thanks...

Image
Image

The difference is even more noticeable when the compressor is in RMS mode. I Guess this is just how a compressor behaves. :roll:
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
Posts: 4166
Joined: Wed Oct 24, 2007 4:50 am

Re: understanding the compressor threshold

Post by fishmonkey » Sun Nov 08, 2015 5:05 am

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/
badbrainz wrote: I'm a drummer, so I'm already at an intellectual disadvantage here

Stromkraft
Posts: 7033
Joined: Wed Jun 25, 2014 11:34 am

Re: understanding the compressor threshold

Post by Stromkraft » Sun Nov 08, 2015 11:49 am

fishmonkey wrote: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.
Make some music!

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