A Schroeder allpass filter is given by the difference equations
x(t) is the input signal,
y(t) is the output signal,
D is the delay time, and
k is the allpass coefficient.
In this UGen,
k is computed as
k == 0.001 ** (delay / decay.abs) * decay.sign (0.001 is -60 dBFS).
The input signal.
The maximum delay time in seconds. Used to initialize the delay buffer size.
Delay time in seconds.
Time for the echoes to decay by 60 decibels. If this time is negative then the feedback coefficient will be negative, thus emphasizing only odd harmonics at an octave lower.
Output will be multiplied by this value.
This value will be added to the output.