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<blockquote data-quote="Michael John" data-source="post: 202146" data-attributes="member: 830"><p>Hi Mark,</p><p></p><p>Those results sound great. Thanks for letting me know.</p><p></p><p></p><p></p><p>Good point. Right now there isn't, but I can see why it would be useful, in that the Target slopes and knee points can be an easier way of specifying a target shape than playing with shelf filters (in Direct Design mode). I'll see what I can do... <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /></p><p></p><p></p><p></p><p>Not that I'm aware of. Increasing difference or error between the ideal and windowed filter at low frequencies is really all that happens when shortening the filter length.</p><p></p><p>Generally speaking, our hearing is slightly less sensitive to spectral dips than it is to boosts. So as you shorten the filter, you could watch the error and lean towards filters where the magnitude error, on the Total Error plots, is slightly higher than 0 dB (that is, the windowed filter is a little lower than the ideal, unwindowed filter on the Export tab.)</p><p></p><p>I'd also suggest avoiding sharp transitions in mag or phase filtering at low frequencies. They'll get smoothed out by the windowing anyway.</p><p></p><p>And, since we're talking about low frequencies - say below 100 or 200 Hz - you could try to see which of the tabs is causing the majority of the differences at the lowest frequency in your project, and see if you can make its lowest frequency a little higher.</p><p></p><p></p><p></p><p>Pre-ringing's an interesting topic. The filters you're creating to flatten the phase do have a maximum phase component - i.e. there are filter coefficients before the filter peak - but since the filter is designed to be the opposite of the speakers natural response, the combined loudspeaker response shouldn't have obvious pre-ringing. This assumes that the loudspeaker's natural response doesn't change too much with level and over time. To see how the speaker's response might vary, you could look at the speaker's filtered response at different drive levels using waterfall and similar tools and there may be some slightly pre-ringing visible. (There was a discussion on the other FIR thread about some of these tools.) You could also try averaging a bunch of measurements at different drive levels, and use the average as input to FIR Designer.</p><p></p><p>I'd be surprised if any pre-ringing audible. I've used linear-phase brick-wall crossovers in the Lake Processors, without any consideration for the natural phase of the loudspeaker drivers, and I've never heard any problems. Maybe others have? With linear-phase brick-wall crossovers, things like steep steps in dispersion pattern off-axis are usually more audible.</p><p></p><p>Back to your DIY60... That's great you're getting such good results with FIDd. Keep me posted on what you find re FIRd and rePhase.</p><p></p><p>Cheers,</p><p>Michael</p></blockquote><p></p>
[QUOTE="Michael John, post: 202146, member: 830"] Hi Mark, Those results sound great. Thanks for letting me know. Good point. Right now there isn't, but I can see why it would be useful, in that the Target slopes and knee points can be an easier way of specifying a target shape than playing with shelf filters (in Direct Design mode). I'll see what I can do... :-) Not that I'm aware of. Increasing difference or error between the ideal and windowed filter at low frequencies is really all that happens when shortening the filter length. Generally speaking, our hearing is slightly less sensitive to spectral dips than it is to boosts. So as you shorten the filter, you could watch the error and lean towards filters where the magnitude error, on the Total Error plots, is slightly higher than 0 dB (that is, the windowed filter is a little lower than the ideal, unwindowed filter on the Export tab.) I'd also suggest avoiding sharp transitions in mag or phase filtering at low frequencies. They'll get smoothed out by the windowing anyway. And, since we're talking about low frequencies - say below 100 or 200 Hz - you could try to see which of the tabs is causing the majority of the differences at the lowest frequency in your project, and see if you can make its lowest frequency a little higher. Pre-ringing's an interesting topic. The filters you're creating to flatten the phase do have a maximum phase component - i.e. there are filter coefficients before the filter peak - but since the filter is designed to be the opposite of the speakers natural response, the combined loudspeaker response shouldn't have obvious pre-ringing. This assumes that the loudspeaker's natural response doesn't change too much with level and over time. To see how the speaker's response might vary, you could look at the speaker's filtered response at different drive levels using waterfall and similar tools and there may be some slightly pre-ringing visible. (There was a discussion on the other FIR thread about some of these tools.) You could also try averaging a bunch of measurements at different drive levels, and use the average as input to FIR Designer. I'd be surprised if any pre-ringing audible. I've used linear-phase brick-wall crossovers in the Lake Processors, without any consideration for the natural phase of the loudspeaker drivers, and I've never heard any problems. Maybe others have? With linear-phase brick-wall crossovers, things like steep steps in dispersion pattern off-axis are usually more audible. Back to your DIY60... That's great you're getting such good results with FIDd. Keep me posted on what you find re FIRd and rePhase. Cheers, Michael [/QUOTE]
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