- Delay-line lengths
mutually prime, and
span successive orders of magnitude
- Allpass filters in series are allpass
- Each allpass expands each nonzero input sample from the
previous stage into an entire infinite allpass impulse
- Allpass sections may be called ``impulse expanders'',
``impulse diffusers'' or simply ``diffusers''
- NOT a physical model of diffuse reflection, but
single reflections are expanded into many reflections,
which is qualitatively what is desired.