Phase correction with all-pass filters

[LF78]

With EQ functionality of REW you can automatically calculate PEQ filters in order to match frequency response to target: is there a way to do the same with AP (all-pass) filters to correct the phase response? In this case the target would be a linear phase of course. AP filters are present in EQ filters window, so they should be supported.

This would be very interesting, since PEQ filters, crossovers, etc... they all introduce phase distortions that could be mitigated with AP filters.

 

[Matthew J Poes]

With EQ functionality of REW you can automatically calculate PEQ filters in order to match frequency response to target: is there a way to do the same with AP (all-pass) filters to correct the phase response? In this case the target would be a linear phase of course. AP filters are present in EQ filters window, so they should be supported.

This would be very interesting, since PEQ filters, crossovers, etc... they all introduce phase distortions that could be mitigated with AP filters.

I'm happy to be corrected if this is wrong, but I don't believe it is possible to apply iir based all pass filters to make a speaker linear phase. That linear phase requires an FIR filter. At least when I have seen tutorials on how to achieve this, they have always made use of an FIR filter.

 

[LF78]

Yes, for an absolute linear phase you need to use FIR filters, however they have other issues (like pre ringing artifacts) that I consider worst than a nonlinear phase response.

I believe that with AP filters you could linearize the phase response a little bit, but without a way to calculate them I don't know how to proceed.

 

[Matthew J Poes]

https://www.minidsp.com/applications/advanced-tools/rephase-fir-tool

You may want to give this a shot. I found it was the easiest way to experiment with phase linearization.

 

[LF78]

Thanks! It doesn't have automatic calculation, but at least I can try to adjust things manually and see the result.