Blue Cat's range also includes a healthy selection of EQs and filters, and their Widening Parametr'EQ is another mastering tool with a twist. It's a stereo equaliser that operates in M/S mode, allowing you to apply different EQ curves to the Mid and Sides components of the signal before they are matrixed back into conventional stereo. [...] I was surprised at how effective the M/S equalisation can be for opening out a mix. A little high shelving boost and low-frequency cut on the Sides channel only can really make things more expansive, without introducing obvious artifacts or leaving a hollow centre, as some stereo width processors do. Sound-wise, the equalisation is transparent without being thin or unnecessarily clinical, and the width of the parametric bands can be set as low as 0.01 octaves, for surgical tasks such as hum removal.
Original Source - Sound On Sound
