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| quote: | Originally posted by mysticalninja
I agree with you, but a compressor does bring up certain frequencies and bring down others depending on the sound source and how you use it, and it has been common for years for engineers to use compression to bring out the click in a kick drum or warm up vocals. That's all I was saying from the begining. |
A compressor doesn't bring up anything and is totally not sensitive to frequency - only the amplitude of a signal. It 'supresses' any part of a signal that exceeds its threshold (doesn't matter what the frequency is).
An expander increases the gain of that part of the signal that exceeds the threshold but thats because it works exactly like a compressor but has a compression ratio of less than 1:1 (i.e. 0.5:1)
A compressor doesn't bring out the 'click' in a kick drum - in fact, it supresses it. If you look at a straight 909 bass drum sample in a wave editor you will notice there is a very sharp, very sudden amplitude peak, then a sudden drop in amplitude as the wavelength increases. As the wave length increases, the frequency goes down so this is the bassiest part of the drum (the lowest part of the pitchbend).
Lets say the peak signal (the first and tallest peak) is at 0dB. If it isn't, normalise the drum so it peaks at 0dB. Now add a compressor.
Set the threshold to -3dB and imagine a horizontal line going across the screen at this point on the y axis. Everything above that line is going to get compressed. (this shouldn't be alot - its mainly the initial click bit.)
Compress it with a ratio of 3:1. This means that for every 3 dB over the threshold, the gain will be reduced to 1dB over the threshold. Everything that peaks below the line is unaffected.
Doing this with both the envelope attack and release will reduce the peak signal by 2dB. You can do this yourself in Soundforge or whatever, but make sure you can see it before and after compression and be able to measure how much the peak has gone down (Soundforge or Audition is ideal).
However, you now have 2dB extra dynamic range, so you can increase the output gain by 2 more dB. Not only that, but everything below our imaginary line is 2dB louder in relation to peak signal (its like a balancing scale. You have taken a weight off 1 scale thus making it lighter compared to the other scale).
Since this is the bassiest part of the drum, it gives the impression that the whole kick drum is bassier. That takes a little emphasis off the click at the start.
I suppose you could say that makes it seem 'warmer'.
If you were to compress this drum to an extreme degree (i.e. using a very low threshold and very high compression ratio) you can completely collapse that initial loud peak and turn it into a very bassy smudge.
Try compressing the same 909 BD with:
Threshold = -50dB
Ratio = 10:1
Output Gain = 0
Envelope Attack = 0
Envelope Release = 0
Knee = Hard
Dont worry about it blowing your head off - it will be very very quiet (to be exact, 45dB quieter). Now, normalise it to 0dB and turn down your speakers. There will be practically no click at all.
Last edited by Derivative on Aug-31-2007 at 12:23
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