A Karplus-Strong UGen
an excitation signal.
upon a negative to positive transition, n samples of the excitation signal will be fed into the delay line, where n = delaytime * sample_rate / 2, using a rectangular envelope (no fading).
the max delay time in seconds (initializes the internal delay buffer).
delay time in seconds.
time for the echoes to decay by 60 decibels. Negative times emphasize odd partials.
the coef of the internal OnePole filter. Values should be between -1 and +1 (larger values will be unstable... so be careful!).