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Old 20th August 2019, 12:35 PM   #131
mabat is offline mabat  Czech Republic
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It should not be hard to connect it to a mesh from Ath4. Just delete the throat surface elements and you are ready to go. I'm sure Gmsh will do it. (Or I can make it an option as well.)
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Old 20th August 2019, 01:47 PM   #132
Patrick Bateman is offline Patrick Bateman  United States
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Originally Posted by 4real View Post
One question though: is there an easy way to control the size of the horn? What I did now is tweak the depth and angles to get in the ballpark of the size I'd like, but that limits me to a specific range of angles. Let's say I want to make a 2:1 (w:h) sized horn that is 90x90 deg. Can the tool do that for me?
I don't think that's possible.

Here's why:

This software, to an extent, works similar to an oblate spheroid curve

Click the image to open in full size.

The OS curve isn't exactly the same as the Peavey curve pictured above, but it is close. The fundamental idea with this waveguide shape is that we're making a gentle transition from the EXIT of the compression driver to the EXIT of the waveguide mouth.

And ATH4 works on a similar concept: if you look at all the parameters, they're mostly there to determine when we transition from one curve to the next.

If all of that makes sense... Then it should be apparent why you can't do a 90x90 horn with a ratio of two to one:

To do so would require a diffraction slot.

I've pondered this quite a bit, and the only method that I could come up with would be to do this:

step 1: make your horn or waveguide in ath4

step 2: then load that into your 3D program to add a diffraction slot after the fact.

But doing it in ath4, without the use of external software, I don't think that's possible. If you have a horn that is twice as wide as it is tall, with a coverage angle of 90x90, it's going to have a diffraction slot.
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Old 20th August 2019, 02:05 PM   #133
mabat is offline mabat  Czech Republic
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That's the other way how to look at it (and it didn't occured to me) and it's true in a sense.

What you CAN do however, is to take an arbitrary, say round, waveguide and make the mouth termination flare to any arbitrary shape, say rectangle 2:1. No problem with that. This is exactly how the outer rectangular shape in Ath4 is done now. It only makes the mouth bigger than necessary (or not?).
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Old 20th August 2019, 02:12 PM   #134
Patrick Bateman is offline Patrick Bateman  United States
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Originally Posted by mabat View Post
That's the other way how to look at it (and it didn't occured to me) and it's true in a sense.

What you CAN do however, is to take an arbitrary, say round, waveguide and make the mouth termination flare to any arbitrary shape, say rectangle 2:1. No problem with that. This is exactly how the outer rectangular shape in Ath4 is done now. It only makes the mouth bigger than necessary (or not?).
Hmmm. This doesn't make sense to me. If I wanted a mouth that measured 2:1, I would have to define that using the parameters "coverage_horizontal" and "coverage_vertical."

IE, if I use a "coverage_horizontal" and a "coverage_vertical" of 90 degrees, I'm not going to get a waveguide that measures 2:1.

To achieve what you describe, you would need to have two variables for "termination.angle", one for horizontal and one for vertical. Right now there's only one "termination.angle"
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Old 21st August 2019, 07:12 AM   #135
mabat is offline mabat  Czech Republic
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I only mentioned a possibility to introduce new parameters that will make it doable. But it's probably not a very good way of making horns anyway. I would allways just let the mouth grow as necessary for the desired coverage. If there are any limits on the mouth size (as allways are), just tweak the parameters to get into that limits.

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Originally Posted by mabat View Post
That's not possible at the moment, I'm afraid ... I see a simple solution however. For a rectangular horn, I will make parameters available for any target mouth dimensions you may like (now it is taken from the raw shape's width and height before the final transformation).
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Old 21st August 2019, 10:42 AM   #136
mabat is offline mabat  Czech Republic
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You know, the reason it is implemented this way is that the calculation "(coverage_angles, roundover_size) --> mouth_size" is not so easy to do backwards. I guess it could be done but with a lot of complication.
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Old 21st August 2019, 12:57 PM   #137
Dmitrij_S is online now Dmitrij_S  Europe
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Originally Posted by jzagaja View Post
Do you think Abec could do phase plug sim too?
I was triyng to do simulations of compression driver in Comsol using linear acoustics module. The simulation results were in good agreement with measurements up to a certain frequency. However, in the upper midrange and at higher frequency, when a thermoviscous layer depth become comparable with linear dimension of the slit, there was a noticeable difference in the measured and modelled SPLs. This is because to get the correct results in the higher frequency range you need to include thermoviscous effects. It is seems, that ABEC3 can include viscous dampg effects (see for meaning of parameters "Ra=", "eta=" and "visc="), however, I did not go into details. If you want to model the phase plugs with ABEC3, you need to learn how to include thermoviscous effect into the phaseplug.
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Old 21st August 2019, 04:35 PM   #138
mabat is offline mabat  Czech Republic
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Thanks Dmitrij for the input, this is something I thought about but couldn't even name precisely.

Greetings to Vilnius! Wonderful city with nice people.
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Old 25th August 2019, 06:41 AM   #139
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I could probably make this tool as an add-on for Fusion 360 to generate parametric horn surfaces there directly, but where to take the time?

Autodesk Fusion 360 API: Help
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Old 25th August 2019, 10:56 PM   #140
daemonsgr is offline daemonsgr  United Kingdom
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Originally Posted by mabat View Post
I could probably make this tool as an add-on for Fusion 360 to generate parametric horn surfaces there directly, but where to take the time?

Autodesk Fusion 360 API: Help

YESSSS!
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