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Multi-Way Conventional loudspeakers with crossovers

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Old 14th March 2019, 08:23 PM   #81
DonVK is offline DonVK  Canada
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Maybe more factets like I've seem on other speakers. Hmm. not so good.
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File Type: jpg horz-8.jpg (45.4 KB, 60 views)
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Old 14th March 2019, 08:25 PM   #82
DonVK is offline DonVK  Canada
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Maybe a longer side facet. ... Nope.
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File Type: jpg horz-5.jpg (46.3 KB, 4 views)
File Type: jpg horz-8.jpg (46.7 KB, 5 views)
File Type: jpg freq_resp.jpg (32.1 KB, 6 views)
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Old 14th March 2019, 08:25 PM   #83
mushroommunk is offline mushroommunk  United States
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I haven't slept in two days so I'm just spitballing.

Wouldn't putting the thing off center also help?

And metrics: Just do a stupid simple one, subtract your polar plot of tweeter from polar plot of mid, sum the differences. Your script will try to minimize that sum.
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Old 14th March 2019, 08:30 PM   #84
DonVK is offline DonVK  Canada
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Back to rounded edges and a shallow waveguide. That looks good, I might change the waveguide a little to widen the horizontal. I probably could get away with less radius on the corners. I could even build that as well. It seems to be a popular design approach for a good reason
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File Type: jpg tweet_td20_elip_wg_elip_baffle2.jpg (27.8 KB, 12 views)
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File Type: jpg horz-5.jpg (39.4 KB, 11 views)
File Type: jpg horz-8.jpg (43.2 KB, 14 views)
File Type: jpg freq_resp.jpg (32.4 KB, 14 views)
File Type: jpg horz_polar.jpg (28.3 KB, 13 views)

Last edited by DonVK; 14th March 2019 at 08:47 PM. Reason: typo
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Old 14th March 2019, 08:46 PM   #85
DonVK is offline DonVK  Canada
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Quote:
Originally Posted by mushroommunk View Post
I haven't slept in two days so I'm just spitballing.

Wouldn't putting the thing off center also help?
Well... shrooms can do that

I have tried offsetting drivers and it causes asymmetric polar response which I don't want. It sounds fine in the sweet spot but IMO makes it smaller as well. You also end up with specific right and left speakers builds.

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Originally Posted by mushroommunk View Post
And metrics: Just do a stupid simple one, subtract your polar plot of tweeter from polar plot of mid, sum the differences. Your script will try to minimize that sum.
I understand what you're suggesting, and the concept is fair for a limited #variables. The problem is the large number of variables required to generate the physical model, and the intermediate processing steps to actually get that model into a mesh format that ABEC could use. Each run on ABEC could take 30 min or more. So I try to get some insight into what direction I should take by trying different shapes. I'm starting to build some intuition to what might work and the last sim seems to be in the ball park.

Last edited by DonVK; 14th March 2019 at 09:07 PM. Reason: typo
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Old 14th March 2019, 09:38 PM   #86
ScottG is offline ScottG  United States
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Note: just because it looks good on a polar, doesn't mean it will sound better.

There are reasons why that weird upper freq. off-axis flair could be beneficial, and why you would NOT want a more directive response (though more uniform).
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Old 14th March 2019, 09:42 PM   #87
DonVK is offline DonVK  Canada
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Quote:
Originally Posted by ScottG View Post
Note: just because it looks good on a polar, doesn't mean it will sound better.
I can accept that. I was trying to get a clean wavefront to start with.

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There are reasons why that weird upper freq. off-axis flair could be beneficial, and why you would NOT want a more directive response (though more uniform).
There's lots of weird here. Which weird and in which post?
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Old 14th March 2019, 09:46 PM   #88
ScottG is offline ScottG  United States
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Beneficial - where it increases in pressure nearing +/-90 degrees relative to 0 degree. (..multiple posts.)

Detrimental - post #84.
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Old 14th March 2019, 09:57 PM   #89
ScottG is offline ScottG  United States
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The reason why it could be beneficial is that we increasingly loose "sensitivity" to off-axis pressure (depending on the bandwidth), and it could be advantageous to effectively "compensate" for this.

Note: we are most sensitive horizontally +/- 30 forward AND rearward (particularly 1.5 kHz to about 7 kHz with emphasis in this bandwidth for localization).

Another reason (again bandwidth dependent) is to "steer" pressure differences (Horizontally) for improved lateral results in one respect or another.
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Last edited by ScottG; 14th March 2019 at 09:59 PM.
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Old 15th March 2019, 01:41 AM   #90
DonVK is offline DonVK  Canada
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That would be true, if for some reason, my sim did not reflect the actual driver performance. That the system's actual off axis perf is different than predicted.

I'd have to measure a system that's built with the intended baffle, extract the differences from the equivalent model's prediction, then rework the baffle to provide that difference (ie. compensation). It could be done and would probably be the only way to fix the horizontal polar. At least I have some examples of what happens when you tinker with the baffle.

I plan on building post#84 (or something close to it) so we shall see when its measured.
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