In Reply to: RE: Absolute phase/polarity posted by Inmate51 on August 5, 2013 at 13:36:06:
You can't fix a group-delay problem with a single time-delay for a given band. The delay is frequency dependent. Some DSP/active boxes have phase correction, and the Thuneau Allocator computer-based DSP crossover has phase correction which it does with what they call "forward/reverse processing". It's kind of cool. By virtue of a latency delay, the process effectively "goes forward in time" (a trick using the latency delay) and causes in effect the opposite of group-delay. Sort of a group-"opposite of delay". Then, the crossover function causes the expected group-delay which in effect cancels out. So yes, you can make pretty square waves with standard filters such as 3rd order Butterworth and 4th order Linkwitz riley. The only trick is you need to know the acoustic function and Fc points for all crossover points, and the -6db point for the LF band, if ported. (This is to do with the group-delay of the ported design Tom was referring to).
Fascinating stuff.
Cheers,
Presto
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Follow Ups
- RE: Absolute phase/polarity - Presto 07:44:13 09/17/13 (0)