In Reply to: RE: "4th has 360 degrees phase shift." ... posted by andyr on July 26, 2016 at 16:31:50:
Hi
To be clear, that 360 degree phase shift happens going from well above to well below the crossover point but yes and when the out put sums flat but one has that phase shift, it is what's called an "all pass" phase response, it also means that the shift is a delay in time where the lower frequencies emerge behind the upper portion.
To make that "go away" so that the sum is all at the same time and like one gets from a single driver covering the entire range is not simple unless one uses FIR filters in DSP where one can separate magnitude and phase. You might want to look at the mini-dsp unit and Re-phase program, the latter is like a graphic equalizer except one can eq the phase independently from the magnitude.
It is possible with passive filters too like we do at work with Synergy horns although one must physically displace the lower F driver to the rear of the upper driver and it requires a non-traditional crossover shape.
The "named" varieties like Butterworth, L&R, Bessel and so on all have that all pass delay and these only sum to flat magnitude when the acoustic centers are aligned.
Hope that helps
Tom
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Follow Ups
- RE: "4th has 360 degrees phase shift." ... - tomservo 05:43:48 07/27/16 (0)