hpass2~ highpass filter Analogous to hpass1~, this second-order IIR highpass filter is made by subtracting a lowpass filtered version of a signal from the signal itself. Logically, the lowpass filter used is lpass2~, a resonant lowpass filter. As with hpass1~, the cutoff frequency in the second inlet of hpass2~ defines the point at which the low frequencies will start to be attenuated. However, hpass2~ also takes a "damping factor", which controls the slope of the cutoff. Damping values greater than 1.41 produce a mild slope similar to that of hpass1~. However, damping factor values less than 1.41 produce moderate to extreme gain boost around the cutoff frequency, characterizing this filter as a resonant highpass filter (the gain boost creates a mild to pronounced resonating effect).

from the library : Jimmies Format : Abstraction Environment : max / msp commercial Max 3.x / 4.x http://forumnet.ircam.fr//rubrique.php3?id_rubrique=65