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Sub enclosure design question
Sub enclosure design question
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Old 21st June 2019, 08:17 AM   #1
Augusts is offline Augusts  Latvia
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Default Sub enclosure design question

Hello

I am putting together a multi way system, but the question is about the subwoofer volume part. Is this ok for a 40cm wide enclosure? The upper right corner - will the air circulate or will the woofer see a smaller box than it actually is?

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A
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Old 21st June 2019, 08:21 AM   #2
TBTL is offline TBTL  Germany
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Based on gut feeling I think it will be OK.

Attached is a suggestion that would avoid the issue, with the added advantage that the midrange driver enclosure is somewhat (maybe not significantly) shaped like the Bowers & Wilkins Nautilus. A true Nautilus style enclosure has an exponentially decreasing cross section and is much longer.


On the image it looks like the baffle lies somewhat deeper than the edges of the side and top panels. This is good for protection of the drivers, but for sound quality it is better to have the baffle flush. This only holds for the midrange driver and tweeter. It does not matter for the woofer.
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Last edited by TBTL; 21st June 2019 at 08:29 AM.
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Old 21st June 2019, 08:31 AM   #3
Augusts is offline Augusts  Latvia
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That is a good idea. I will go that way
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Old 21st June 2019, 09:20 AM   #4
ICG is offline ICG  Germany
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The angled board is indeed a very good idea. The port is extremely long and got a 90° turn, that's not ideal but the port surface is generous, if it goes over the whole width of the speaker and that will prevent port noise from air movement. Because of the big dimensions, length resonances could become a problem. A port which ends directly at the wall has to be shortened by ~20%. At such extreme dimensions of the port it is often better to use a passive radiator instead. It makes tuning the speaker much easier because you can very easily change the weight on the passive membrane. And it does not introduce any length-resonances and does not take up enclosure volume.

Maybe I'm interpreting it wrong but are the side walls stick out from the baffle? If that's the case, it will have a bad influence on the dispersion in the midrange and heights, as it reflects the sound and the stage/room impression and resolution will suffer a lot.
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Old 21st June 2019, 09:25 AM   #5
Augusts is offline Augusts  Latvia
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I'm thinking something like this

Click the image to open in full size.

The black rectangle on front would be a grille

PR is also a good idea but that would at least be another 200euros or so.
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Old 21st June 2019, 09:35 AM   #6
Augusts is offline Augusts  Latvia
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Also I'm looking now at Dayton's PR, WinISD simulates better with a port for the LAB12c driver - better response at 25-30 Hz
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Old 21st June 2019, 09:45 AM   #7
Zero D is offline Zero D  United Kingdom
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In the first post, the area behind the mid could act as a stub. This might or might not be beneficial. But, without actually designing it in properly, it's better to angle it as others have said
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Old 21st June 2019, 10:38 AM   #8
ICG is offline ICG  Germany
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To put the tweeter on the side of the midrange will lead to horizontal interference and lobing. Yes, it's been done in the 70s and on PA fullrange speakers even longer but it's obviously not a PA speaker and you got enough space on the baffle for all drivers anyway. It will be much better if you align the center of the tweeter and mid vertically on one line.

The reinforcement in the port is a very good idea, I wanted to suggest that too but forgot it then.
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Old 21st June 2019, 10:40 AM   #9
ICG is offline ICG  Germany
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Quote:
Originally Posted by Augusts View Post
Also I'm looking now at Dayton's PR, WinISD simulates better with a port for the LAB12c driver - better response at 25-30 Hz
It performs ..better? I doubt you've simulated the losses of the long port. And: You are aware you can tune the PR by adding weight?
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Old 22nd June 2019, 03:50 PM   #10
Augusts is offline Augusts  Latvia
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Click the image to open in full size.


It is louder but does not go that low as a port.
The yellow one is a combination of 15" DaytonPR, the other ones are 12" and 10"
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