- Allpass impulse response only ``colorless'' when extremely short
(less than 10 ms or so).
- Long allpass impulse responses sound like feedback comb-filters
- The difference between an allpass and feedback-comb-filter impulse
response is one echo!
- Steady-state tones (sinusoids) really do see
the same gain at every frequency in an allpass, while a comb filter
has widely varying gains.