Not compressing the sound, but rather phase reversing and decreasing it that way. It's a lot more natural and not fxxking up the original sound source. Also it's dual band, which means it saves you time and plugins. The best deesser I've heard. The dbx-902 & dbx-502 were the top for me, but this one took their place because of the sheer face that it replaces 2 of them in a single unit and sounds more natural and doesn't kill any dynamics.