
I've been wanting to mention that something is strange about the compressor, but I wasn't sure until I did some exclusive tests.
Put short: The compressor attacks more than it should.
Put long: I'll be talking in absolute values here, just to keep things simple.
In case the compressor is configured this way: Threshold=256, Attack=0, Release=1, Slope=100%
- Then the compressor will duck more than 100%, if the input volume of a sine wave is greater than 356 (that's the original volume + 100). So the output will be quieter than the allowed threshold. This must not happen, if the slope is ==100%. Instead "100%" should be just as much as we need to keep the output volume at 256, so to stay conform with the threshold's limit.
In case Slope is ==40%
- Then the compressor will not compress an absolute loudness of 256+100 so much, that only a loudness of 256 remains. A bit more comes through. I'd say that's okay for a slope of 40%.
But if the input loudness reaches an absolute value of 656 and the Slope is still at 40%
- Then again the compressor's output will become quieter than its threshold allowed. Only at an absolute loudness of 456 (~ original+80%) the compressor won't duck more than its Slope and Threshold allows.
Conclusion is:
If the Sloope is < 100%, you can never compress a static portion of a signal. It's always possible to boost the input so much that the whole signal gets muted. In other words, you can never say "10% of my signal will remain uncompressed".
If the Slope is == 100%, you can never boost quiet parts to the level of the compressor's thresold. Because louder parts will be compressed more than 100%, that's what causes the unusual 'muting' in the compressor.
This example shows how the compressor is working with its default values, except of the Attack time, which is set to 0. It's being fed with a sine wave whose volume level is raising each time from 256, over 356 ... and finally to 656. Don't bother about the peaks that get through. Only the part behind it is important.
This wave file shows how a compressor should manipulate the same fading sine-wave. In a wave editor you'll see how its loudness is kept longer at one level each time.
As always, I'm always there if you should need more info.