The B equalization suite is based on the Second Order Section (SOS) biquad UGen.
 this is a pseudo UGen. BHiPass4 is built by cascading 2 SOS sections.
input signal to be processed.
cutoff frequency. WARNING: due to the nature of its implementation frequency values close to 0 may cause glitches and/or extremely loud audio artifacts!
the reciprocal of Q. bandwidth / cutoffFreq.