in what scenario is it useful?
thanks

 

If you use it for example on the drum bus where you send all you individual elements (kick, snare, hht, percs), and it's a wide band compressor (and not a multi) activating the hp filter in the side chain and setting it adequately will avoid the kick and elements that are in the low part of the spectrum (with a lot of energy) to drive all the compression. The compressor will not overeact to the activity in this part of the spectrum, and focus more on the dynamic of the elements in the rest of the spectrum.
With this you can then have different strategies regarding your compression, for instance where you place you threshold, you'll have more margin on that side...

 

Last edited: Nov 24, 2019

In short, all freq outside the filter are not compressed.
For example, all freqs below low cut, aka HPF.

Often, not always, used on drum bus to obtain the BD's power.