apass2~ all-pass filter This is a second-order IIR (infinite impulse response) all-pass filter which performs a symmetric (log scale) phase shift, without modifying the frequency content of the input signal.	from the library : Jimmies Format : Abstraction Environment : max / msp commercial Max 3.x / 4.x http://forumnet.ircam.fr//rubrique.php3?id_rubrique=65