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Old 22nd January 2020, 01:53 PM   #841
Ro808 is offline Ro808  Netherlands
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Quote:
Originally Posted by mabat View Post
You are free to try: Acoustic Horn Design The Easy Way (Ath4)
(it was 1.4")
This will have to wait until I get home.
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Old 22nd January 2020, 02:19 PM   #842
pelanj is online now pelanj  Czech Republic
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Ok, large waveguide like this needs some optimization in the script. It is running already for almost three hours All I would be interested in is the 20 - 2000 Hz range max. So I tried to change some parameters and will see.

Last edited by pelanj; 22nd January 2020 at 02:24 PM.
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Old 22nd January 2020, 02:30 PM   #843
mabat is offline mabat  Czech Republic
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Sure, you can change that in the script or in the "solving.txt" in the generated ABEC project - frequency range, number of points and mesh resolution. And of course you can also reduce the basic mesh fidelity directly via Mesh.* parameters.

Remember that this will be only a crude approximation where a rigid flat disc is still assumed as the source.
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Last edited by mabat; 22nd January 2020 at 02:33 PM.
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Old 22nd January 2020, 04:29 PM   #844
mabat is offline mabat  Czech Republic
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Superformula!

OK, now the fun may begin. So far the only shape-curve (see the documentation) available was a superellipse. From now on it is possible to define a superformula (see wikipedia).

See also Example 22 | Superformula Shape | Super-formula Plotter for examples of various shapes - you will need to understand this.

The definition in the script file looks like this (the numbers for SF are: a, b, m, n1, n2, n3):

ShapeCurve = SF
SF = 2,1,4,8,12,12
SF.Rot = 0


The absolute size of the shape-curve is computed from Coverage_Horizontal and Depth.ConicSectionPart. This sets the width of the shape curve which is scaled so that just fits this dimension. Parameter SF.Rot gives an arbitrary rotation of the mouth if needed. Attached are two demo scripts. The only limitation for now is that for ABEC simulation you need quarter-space symmetry. I yet have to implement full mesh export (and it will take a heck of a time to run those sims). Eventually you can still use the "raw2rect" parameter to make the mouth rectangular (and force the symmetry where it makes sense).

The download: www.at-horns.eu/release/ath-4.4.1.zip
Attached Images
File Type: png sf1-1.PNG (271.2 KB, 181 views)
File Type: png sf2.PNG (353.8 KB, 456 views)
Attached Files
File Type: zip sf1.zip (123.5 KB, 14 views)
File Type: zip sf2.zip (236.8 KB, 9 views)
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Last edited by mabat; 22nd January 2020 at 04:36 PM.
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Old 22nd January 2020, 04:42 PM   #845
mabat is offline mabat  Czech Republic
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Enjoy!
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Old 22nd January 2020, 04:53 PM   #846
mabat is offline mabat  Czech Republic
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Just a picture taken from wikipedia to give you some basic guide for the SF numbers (m, n1, n2, n3). With a, b you basically set the width/height ratio here, not the absolute size (as explained above).
I imagine the second shape will be the most useful.
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File Type: png sf_param.png (108.8 KB, 183 views)
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Old 22nd January 2020, 05:14 PM   #847
mabat is offline mabat  Czech Republic
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I quickly tested the sf1 (demo), it's really nothing special -
Attached Images
File Type: png sf1.PNG (387.3 KB, 162 views)
File Type: png sf1-h.png (21.7 KB, 64 views)
File Type: png sf1-v.png (22.5 KB, 49 views)
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Old 22nd January 2020, 06:03 PM   #848
Patrick Bateman is offline Patrick Bateman  United States
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Click the image to open in full size.

With these "DNA" arrays that I like to build, the reason that they work is basically because they're asymmetrical on the X and the Y axis.

IE, in a conventional D'Appolito array, there will be off-axis nulls at predictable frequencies, and the nulls are caused by pathlength differences. In particular, when the pathlength of two woofers is 180 degrees out of phase, you get a deep null.

So, the DNA array is an elegant solution: NONE of the drivers share the same X or Y axis, hence the smoother response.

Click the image to open in full size.

But once all of that made sense, it hit me that another way to implement the DNA array would be to simply use an odd number of drivers in a ring. Five drivers in particular is an attractive number. It allows for spacing that's nearly as tight as four, and no driver shares the same X or Y axis. But it requires an oddly shaped waveguide...
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Old 22nd January 2020, 06:07 PM   #849
mabat is offline mabat  Czech Republic
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Piece of cake now
I'm only a bit sceptical about the result. Well, I may be surprised.
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Old 22nd January 2020, 06:32 PM   #850
Patrick Bateman is offline Patrick Bateman  United States
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This site allows you to visualize what tweaking the paramets does, in real time:

http://benjaminbojko.com/work/showca...s/supershapes/
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