This is a resonant filter whose impulse response is like that of a sine wave with a Decay2 envelope over it. It is possible to control the attacktime and decaytime.
Formlet is equivalent to:
The great advantage to this filter over FOF is that there is no limit to the number of overlapping grains since the grain is just the impulse response of the filter.
The input signal.
Resonant frequency in Hertz.
60 dB attack time in seconds.
60 dB decay time in seconds.
Note that if attacktime == decaytime then the signal cancels out and if attacktime > decaytime then the impulse response is inverted.