Audacity Forum

Hi -- anybody have any experience with setting the values of knee radius in the SC4 compressor options? The range given is 1 to 10 dB, but I don't know what range of numbers corresponds to soft, medium, and hard knee.

Thanks -- Glenn Harvey

If you have a graph to represent the compression (like you get with the other "Compressor" effect) the "knee radius" would be a curve that joins the line below the threshold and the line above the threshold. The larger this curve, the softer the knee. Conversely, a small radius curve would correspond to a "hard knee".

With it set to a soft knee, the compression begins to be applied way below the "threshold" setting and gradually increases (up to the amount set by the "ratio" setting) as the level increases, whereas with a hard knee, the compression does not start to kick in until very close to the threshold, and then increases to the amount set by the "ratio" parameter just above the threshold.

In practice you will not hear a great deal of difference between the two, other that the resulting wave will have a greater amplitude using a hard knee than if you use a soft knee (this is relevant if you use the "Make-up gain").

The soft knee should give a more subtle compression, particularly if using "RMS/peak" set to "0" (RMS).