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-   -   Acoustic Horn Design The Easy Way (Ath4) (https://www.diyaudio.com/forums/multi-way/338806-acoustic-horn-design-easy-ath4.html)

Patrick Bateman 6th June 2019 10:54 PM

Oh, because I am using the OS waveaguide. Not the ATH15.

Patrick Bateman 6th June 2019 11:01 PM

I just ran the sim for ATH15. Here's what I got:

https://imgur.com/0v12utV.png
1568 nodes, 3024 triangles in the MSH

https://imgur.com/hdx8Wye.png
1568 vertices, 3024 faces in the STL

I had to modify the ath15.cfg file to make an error go away. There's a path set for the output. The error doesn't seem to break anything, but it might confuse people.

Here's the line I commented out:

Out.DestDir = "D:\Horns" ; current directory by default

Patrick Bateman 6th June 2019 11:08 PM

By the way, can I mention what a ridiculous achievment this is?

I spent the better part of December 2018 learning ABEC, and while I was doing it, I mentioned to my wife that I wasn't sure if I could pull it off. ABEC is possibly the most difficult piece of software I've ever tried to learn. Besides being miserably difficult to learn, it's also unbelievably time consuming, because even on a modern system it takes a long time to render, and sometimes it seems like it will never end. It's not unusual to spend four hours waiting for a ABEC render to finish.

On top of that, I've been doing this for over two decades. So it's not like I just stumbled into this forum, I have a fairly decent record of learning software. (That's my day job, I do software consulting. My gig is basically learning new software and then implementing it for clients who don't have existing resources that know the software.)

So the idea that your software can simply spit out an ABEC model is just unreal.

What's crazier is that I managed to get it working *without reading the manual.*

Kudos to you sir, this is an incredibly elegant piece of software. I wish Google or Oracle had people like you working there.

Patrick Bateman 6th June 2019 11:17 PM

https://imgur.com/ZEQrI9Y.png

FIVE MINUTES

That's how long it took me to make this waveguide

Okay, I know a lot of you guys just BUY waveguides, but I'm one of those weirdos who designs my own, and they routinely take me eight hours or more.

And that's just to make the model in 123D.

This absolutely ridiculous piece of software just generated a waveguide in five minutes. All I had to do was plugin my horizontal and vertical beamwidth, and then tweak the depth until the size was what I wanted.

This is nuts.

Patrick Bateman 7th June 2019 12:19 AM

Quote:

Originally Posted by FredrikC (https://www.diyaudio.com/forums/multi-way/338806-acoustic-horn-design-easy-ath4-post5814846.html#post5814846)
Great, just tried the ATH15 example and it generates the STL and the Abec project files, but ABEC freezes when I try to open the project file. The STL looks fine.

Does it matter that I use Abec Pro?

Where to find the dll should be in the documentation or perhaps distrubte the .dll with your software if gmesh allow it.


EDIT: My bad, it just took some time to load because the mesh was so fine. Much finer than the STL??

OK, I am having a similar issue.

I'm working to fix it.

The first issues is that the "observation.txt" that is generated is nearly empty, and that won't work.

The project generated by the OS waveguide script works fine, so I tried substituting that observation.txt instead, but it still doesn't work.

The wireframe that should appear in the 'Drawing' tab is absent. It is present in the OS waveguide project, so it looks like that script is working.

I'm poring over "solving.txt" to see if that's the issue.

Patrick Bateman 7th June 2019 12:33 AM

In "solving" for the OS waveguide, I noticed that there's one domain, but in the ath15 waveguide, there are zero.

I think the problem is in the mesh that's generated. Here's the header for the OS waveguide mesh generated by ath4.exe:

$MeshFormat
2.2 0 8
$EndMeshFormat
$PhysicalNames
3
2 10 "drive"
2 20 "wg"
2 30 "ifc"
$EndPhysicalNames
$Nodes
849

And here's the header for the ath15 mesh. Note the missing fields.

$MeshFormat
2.2 0 8
$EndMeshFormat
$Nodes
1568

Patrick Bateman 7th June 2019 01:11 AM

OK, I am 90% sure that I figured it out. ABEC is grinding away right now, so I can't say 100% that this is the solution. But if you're reading impatiently, here's how I got it to work (maybe):

First thing, take a look at the ath4 configuration file for an OS waveguide, which is named "oswg.cfg"

In that file, you'll notice two things:

1) "Out.Write_MSH" is set to "NO"
2) There are a series of settings for "ABEC.Polars"

In order to get the ATH15 waveguide to work, I had to make those lines look like the lines from "oswg.cfg"

Basically I changed "Out.Write_MSH" to "NO" from "YES"
and I added the lines for "ABEC.Polars"

By doing so, I was able to simulate the waveguide in ABEC.

One caveat : I've noticed that ABEC isn't able to make it's pretty 3D pictures. I think that's because there's something missing from "observation.txt"

Having said that, you CAN see the polars in VACs, which is really what we're after, right?

Patrick Bateman 7th June 2019 01:29 AM

https://4.bp.blogspot.com/_COvnfAy4R...0/dsc_4913.jpg
Here is a JBL PT waveguide

https://i188.photobucket.com/albums/.../Econowave.jpg

Here's the measurement that Geddes did, from this post : Great Waveguide List

Note - the Geddes measurement is normalized. That will become important in a sec (hang in here...)

https://imgur.com/2ixPaHK.jpg
Here's the measurement I did. Mine *isn't* normalized.

https://imgur.com/KSL8jBR.jpg
Here's a waveguide that I made with ATH4 today. It's basically the closest I could get to a JBL progressive transition waveguide, using this software

https://imgur.com/W2Muhhx.jpg
Here's the predicted polars from ABEC

The super cool thing, is that this entire process took about 90 minutes, which is just ridiculous. A month ago, this would've taken me three or four DAYS.

If you look at the predicted polars, the *shape* and the *consistency* is quite close to my measurement of the JBL PT waveguide.

So I'd say this is a big "win", the ability to create waveguides on the command line, instead of making molds and measuring waveguides. The first waveguide I made, over ten years ago, took a WEEK.

Now, you're probably wondering "why is Bateman's measurement so consistent?" IE, why are the lines in my measurement bundled together so tightly?

This was a problem with my measurement technique. Back in the day, I used to do polars in a straight line. IE, I would move the microphone from left to right.

https://cdn.teachersprintables.net/s...-10_Slices.png
When you are measuring a speaker, you should be moving in an ARC. I was moving in a LINE.

The net effect of how I was doing my polars, is that it was making the off-axis response louder than it should have been. That's why the lines are bundled so closely on that measurement. (It also depends on whether you set your reference ON axis or OFF.)

I fixed that issue years ago; all my measurements in the last 2-3 years have been in an arc.

Patrick Bateman 7th June 2019 03:11 AM

https://imgur.com/EoPjpxZ.png

Looks like it's possible to take the STLs generated by ath4 and load them up in 123D. This is great! It means:

1) they can be 3D printed
2) More importantly... they can be changed. For instance, I could "unitize" this waveguide by adding some midranges.

I am loving this program...

Side note: in order to get it into 123D, I had to load the STL generated by ath4 into Meshmixer, and have Meshmixer repair it. I believe this is because the STL has no thickness whatsoever, it is basically a cloud of x,y,z coordinates, similar to a mesh file. Meshmixer was able to "close" the mesh and turn it into a solid.

After meshmixer took the STL file and turned it into a solid, I used that solid to 'slice' a void out of a block in 123D. Similar to a male/female mold. Meshmixer produces a "male" mold, I turn that into a "female" mold in 123D.

diyuser2010 7th June 2019 04:03 AM

Quote:

Originally Posted by Patrick Bateman (https://www.diyaudio.com/forums/multi-way/338806-acoustic-horn-design-easy-ath4-post5815086.html#post5815086)

Now, you're probably wondering "why is Bateman's measurement so consistent?" IE, why are the lines in my measurement bundled together so tightly?

This was a problem with my measurement technique. Back in the day, I used to do polars in a straight line. IE, I would move the microphone from left to right.

https://cdn.teachersprintables.net/s...-10_Slices.png
When you are measuring a speaker, you should be moving in an ARC. I was moving in a LINE.

The net effect of how I was doing my polars, is that it was making the off-axis response louder than it should have been. That's why the lines are bundled so closely on that measurement. (It also depends on whether you set your reference ON axis or OFF.)

I fixed that issue years ago; all my measurements in the last 2-3 years have been in an arc.


Are you using a turntable with a stationary microphone? From the sounds of it, you are keeping the speaker stationary and moving the mic.



A turntable is not a difficult thing to build, a piece of plywood, circle jig and a lazy susan bearing.



https://i.imgur.com/Exx6iHn.png


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