coef_bpass3~ bandboost or band-cut filter This abstraction is designed to calculate coefficients for biquad~ which create a bandboost or band-cut filter. It does not contain a biquad~ and must therefore be connected to one. Connecting it to any other object is meaningless. Like the band-pass filter, it also has a center frequency and bandwidth (here the bandwidth is expressed in octaves instead of Hz). However, unlike a bandpass or notch filter it lets all frequencies pass through, and only attenuates or boosts the frequencies inside it’s band. The boost or cut is defined in decibels (positive for a boost/gain, and negative for a cut/ attenuation). Remember that a signal’s amplitude is doubled when it is boosted by 6dB and halved when it is attenuated by 6dB.

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