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<blockquote data-quote="Bennett Prescott" data-source="post: 41319" data-attributes="member: 4">Re: out of band eq filtersEQ filters, at least the kind you and I are talking about here, are minimum phase. That means that every change in magnitude will create an equal change in phase, i.e. you can take the magnitude response of a minimum phase system and draw precisely what the phase response will be, and vice versa.The problem is that filters that are not bandpass filters (i.e. parametric and shelf EQ) only create little phase changes. I almost always find that if I need to adjust the phase slope I need to do it by tens of degrees over several octaves. The phase shift that EQ makes is perfect for counteracting errors in the loudspeaker&#039;s phase due to magnitude response ripple, but you would have to use pretty big EQ to do the kind of alignment work we&#039;re talking about. Usually you&#039;re putting a XO filter there anyway, why not use it?For example, here is the phase and magnitude response of some roughly 1/2 octave parametrics:[ATTACH]150075[/ATTACH]And here it is for some &quot;6dB/octave&quot; slope shelving filters:[ATTACH]150076[/ATTACH]Here&#039;s what some Bessel filters look like (imagine that an all pass looks like the purple trace without the magnitude change):[ATTACH]150077[/ATTACH]Use the one that matches the phase shift you need!</blockquote>

[QUOTE="Bennett Prescott, post: 41319, member: 4"] Re: out of band eq filters EQ filters, at least the kind you and I are talking about here, are minimum phase. That means that every change in magnitude will create an equal change in phase, i.e. you can take the magnitude response of a minimum phase system and draw precisely what the phase response will be, and vice versa. The problem is that filters that are not bandpass filters (i.e. parametric and shelf EQ) only create little phase changes. I almost always find that if I need to adjust the phase slope I need to do it by tens of degrees over several octaves. The phase shift that EQ makes is perfect for counteracting errors in the loudspeaker's phase due to magnitude response ripple, but you would have to use pretty big EQ to do the kind of alignment work we're talking about. Usually you're putting a XO filter there anyway, why not use it? For example, here is the phase and magnitude response of some roughly 1/2 octave parametrics: [ATTACH=CONFIG]150075.vB5-legacyid=2531[/ATTACH] And here it is for some "6dB/octave" slope shelving filters: [ATTACH=CONFIG]150076.vB5-legacyid=2532[/ATTACH] Here's what some Bessel filters look like (imagine that an all pass looks like the purple trace without the magnitude change): [ATTACH=CONFIG]150077.vB5-legacyid=2533[/ATTACH] Use the one that matches the phase shift you need! [/QUOTE]

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