Acoustic Horn Design – The Easy Way (Ath4)

[mabat]

Has anyone any experience with BMS 4554? It has a conical output approx. 52° wide, beginning with only around 17 mm (0,7") phase plug opening. Is this driver just a bigger (i.e. 1.4") version of a smaller one they produce?

I guess I could add an option of a conical extension at the throat to see the infuence. I wonder if this would have any advantage or not.

 

[Flaesh]

4550\4554\4555 seem basically the same except different phase plugs and throats. I have only 4550, but never seen 4\5 offline)).

 

[mabat]

Now I see I wrote 52° exit angle for 4554 - that is nonsense, it is 26° total. OK, I found 4550 has about 14°.

 

[kipman725]

I emailed BMS about the differences before:

These drivers all use the same voice coil assemblies, but the 4594 hast a bigger HF magnet system than 4592 and 4595 and therefore a little better HF response.

Also the exit angles are different:

4592 – 10.0°

4594 – 3.0°

4504 – 10.8°
[\quote]

 

[mabat]

I believe these are (very) different drivers. I actually have a pair of 4554 but haven't tried them yet.

 

[OscarS]

Honestly, I wouldn't bother making waveguides for AMTs. In my view, they are either too small to be really useful or they beam terribly.

Thanks for your input, except that I have already made a crude version out of an existing horn from Dayton Audio, and the results were exactly what I was looking for.

 

[mabat]

OK, I can imagine a situation where some horn is better than no horn at all. And of course it depends on what you are looking for. We may differ in that, that's fine. Whatever floats your boat

 

[Patrick Bateman]

I would love to be able to make a custom horn design for my AMT tweeters, but then how does one go about having it physically made?

3D printer

Check out my threads on how to make waveguides in 123D. The same ideas apply to an AMT. Basically you want a spline which gently connects the output of the radiator to the baffle. That's why these waveguides have these big roundovers.

 

[mrk7]

Hi Marcel, thanks for making your software available. It's awesome!

 

[mrk7]

I could make an option of a dome tweeter instead of a plane wave (which is what it is now) for the throat.

This would be brilliant!

Should I include the surround?

Including half of the surround in simulations appears to generate valid results from what I've seen:


Open source Waveguides for CNC & 3D printing!

BTW, the wavefront could also by modeled as non-flat. I only don't know if there is anyone who could utilize such feature.

I for one would be interested

 

[mrk7]

Yes, this would be an awesome feature. One way you might implement it is to add a stanza to the cfg file for the following:

1) diameter of dome

2) diameter of surround

3) height of dome

You might want to set things up so that these parameters would override the "ThroatDiameter" parameter. In other words, if the user selected a 25mm dome with a 5mm surround, that would yield a throat of 35mm. So if the user selected a throat of 25mm or 50mm, that would cause issues with the model. (Because there's a mismatch.) So you might want to have the dome settings "override" the "ThroatDiameter" setting in the config file.

Great idea Patrick Bateman!

 

[OscarS]

3D printer

Check out my threads on how to make waveguides in 123D. The same ideas apply to an AMT. Basically you want a spline which gently connects the output of the radiator to the baffle. That's why these waveguides have these big roundovers.

I figured that would be the answer, I just wasn't sure if everyone and the kid down the block were buying their own 3D printers or if they were having them outsourced somewhere.

I modified a home-brewed Dayton H110 horn to an AMT and the results were fantastic for what I needed, but I'm torn as to how to make the aesthetics better. V1.0 was fiberglass/resin to match the throat to the AMT aperture. V1.2 (in the works) will be slicing/merging two H110 horns to get the throat dimension I need without resorting to fiberglass/resin. But of course a 3D printed horn would be even better!

 

[Ro808]

Now I see I wrote 52° exit angle for 4554 - that is nonsense, it is 26° total. OK, I found 4550 has about 14°.

Exit angle of the BMS 4554 is 26.7º (confirmed by BMS).
I have 2 pairs, Mk1 (metal brand plate) and Mk2 (plastic brand plate), exit angles are identical.

 

[Gaga]

Hi mabat,

Thanks a lot for presenting your software here!

I just started to play around with it a bit and have a few questions/comments:
- There is a new gmsh-version 4.4 out. When I installed the gmsh-4.4.dll file, it didn't work. I had to install the 4.3-file. Is this ok - or would you update your prog to gmsh 4.4?
- I did run the 'small' example first. Had the same issue as previously described here, i.e. had to modify the output-folder path. Everything fine then.
- When running ath4 I got the ABEC project result and mesh-file. I'd appreciate to get a *.step-file as well, which would ease up the transfer to a CAD program to finally print the horn. Any possibility?

I could make an option of a dome tweeter instead of a plane wave (which is what it is now) for the throat. At least I believe it would be possible. Only it is not so obvious how to do it. Should I include the surround? How to define the shape? Or does that make any sense at all?

This would be great. I fully agree with Patricks comments here.

Thanks again for this great piece of software,
Christoph

 

[Hylle]

When you talk exit angle on a compressiondriver, how is that defined?

 

[danibosn]

- There is a new gmsh-version 4.4 out. When I installed the gmsh-4.4.dll file, it didn't work. I had to install the 4.3-file. Is this ok - or would you update your prog to gmsh 4.4?

Christoph

Hi

First I would like to thank Marcel for giving to community such piece off tool

Second is that I have same problem as Gaga but could not find download link for gmsh 4.3. So if somebody has a link, please, post it

regards

 

[Patrick Bateman]

When you talk exit angle on a compressiondriver, how is that defined?

1) measure the diameter at the exit of the phase plug

2) measure the diameter at the throat

3) use the pythagorean theorem to calculate the exit angle

 

[Gaga]

Hi,

Second is that I have same problem as Gaga but could not find download link for gmsh 4.3. So if somebody has a link, please, post it

Yes, it's not obvious. The link is given at the main page:

All versions: binaries and sources

The direct link for Windows is here under 'http://gmsh.info/bin/Windows/'.

Just download the 4.3. version.

 

[carlthess40]

Can this program be use to make full range wood horns? Or mid/high wood horns?

 

[danibosn]

Thank's Gaga