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<blockquote data-quote="Michael John" data-source="post: 201754" data-attributes="member: 830"><p>Hi Peter,</p><p></p><p>Yep, I understand.</p><p></p><p>>> If you don't have FIR per driver, than you have (much) less options to correct the (out of band) phase behaviour of the individual drivers.</p><p>With detailed IIR all-pass and parametric filters (e.g. Lake processing), one can do fairly complex out-of-band magnitude adjustments and phase matching of the two drivers. A global FIR can then undo the phase that's been added by those IIR's.</p><p></p><p>>> You cannot correct the phase per driver with a global FIR filter</p><p>That's right, but I don't think first linearising the phase of individual drivers needs to be the primary goal. IMHO the goals are suppressing out-of-band oddities and phase matching over the most of the desired coverage angle. If that is achieved, then a single global FIR linearisation filter can work fine.</p><p></p><p>Specifically for a horn, correcting some of the horn reflections via phase linearisation can be done either on the horn alone or in a global filter. The end result will be the same for the horn frequency range above crossover.</p><p></p><p>The notion of individually linearising the drivers first is fine, but it can be hard to know how far to go into the out-of-band areas. Too far in the low end, and the linearisation comes at the cost of increased latency in the FIR filters and possibly some discontinuities in the mag/phase of the filters. Going just far enough keeps the FIR filters as short as necessary to get the job done. Doing a mag & phase match the old way first and FIR correcting the aggregate, I think, may be easier and may result in slightly lower overall latency. (I could be wrong. <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /> )</p></blockquote><p></p>
[QUOTE="Michael John, post: 201754, member: 830"] Hi Peter, Yep, I understand. >> If you don't have FIR per driver, than you have (much) less options to correct the (out of band) phase behaviour of the individual drivers. With detailed IIR all-pass and parametric filters (e.g. Lake processing), one can do fairly complex out-of-band magnitude adjustments and phase matching of the two drivers. A global FIR can then undo the phase that's been added by those IIR's. >> You cannot correct the phase per driver with a global FIR filter That's right, but I don't think first linearising the phase of individual drivers needs to be the primary goal. IMHO the goals are suppressing out-of-band oddities and phase matching over the most of the desired coverage angle. If that is achieved, then a single global FIR linearisation filter can work fine. Specifically for a horn, correcting some of the horn reflections via phase linearisation can be done either on the horn alone or in a global filter. The end result will be the same for the horn frequency range above crossover. The notion of individually linearising the drivers first is fine, but it can be hard to know how far to go into the out-of-band areas. Too far in the low end, and the linearisation comes at the cost of increased latency in the FIR filters and possibly some discontinuities in the mag/phase of the filters. Going just far enough keeps the FIR filters as short as necessary to get the job done. Doing a mag & phase match the old way first and FIR correcting the aggregate, I think, may be easier and may result in slightly lower overall latency. (I could be wrong. :-) ) [/QUOTE]
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