I already have a 4552 adapter optimized - the initial throat diameter has been reduced a tiny bit, as it still seems possible, otherwise it's basically the same as for the 4554.
Another driver with an approx. 16mm phase plug exit is the Celestion 1412, it looks accessible in this photo: https://www.diyaudio.com/community/...ivers-a-discussion.397699/page-8#post-7515387
@matbat I bought and downloaded the Gen 2 Horn as well as the 150mm throat adapter to try to understand what was going on in that transition. It appears to me that in order to make a smooth transition from the 0 degree exit at the driver mouth to the horn you've established a smooth curve that actually necks down to a diameter less than the CD exit - approximately 28.8mm vs. the 36mm. Is this reduction doing something to the loading of the CD, or is this just to make the transition from the 53.7mm horn throat opening to the 36mm CD opening smooth? I.e., if you had infinite control, would something like what I've drawn below be better? To explain - I took the curvature of the horn mouth and moved it, which expands the overall diameter of the horn from 520mm to 571mm, and then established a nurbs curve that matches the exit of the CD (using 8 degrees for the example for a B+C driver) to the tangent curvature of the throat of the horn itself. See the attached image:
Attachments
With the ath tool you can simulate all of this yourself. This is the profile you drew, approximted by eye as a single R-OSSE curve.
As I said, this adapter didn't work very well with a driver that it was tested with. It caused a too big efficiency drop on the lower end of the passband. I don't know what else to say, it was just an idea to try (and it may work better with a different driver, that's why I kept it there).
https://www.desmos.com/calculator/vzgnllxfqm
And this is the ath sript:
As I said, this adapter didn't work very well with a driver that it was tested with. It caused a too big efficiency drop on the lower end of the passband. I don't know what else to say, it was just an idea to try (and it may work better with a different driver, that's why I kept it there).
https://www.desmos.com/calculator/vzgnllxfqm
And this is the ath sript:
Code:
R-OSSE = {
R = 285
r0 = 18
a = 28
a0 = 8
k = 14
m = 0.83
r = 0.47
b = 0.15
q = 3.9
}
Mesh.LengthSegments = 120
Mesh.AngularSegments = 8
Mesh.SubdomainSlices =
Mesh.ThroatExtSegments = 24
Mesh.WallThickness = 6
ABEC.SimType = 2
ABEC.SimProfile = 0
ABEC.MeshFrequency = 30000
ABEC.NumFrequencies = 64
ABEC.Abscissa = 1
ABEC.f1 = 200
ABEC.f2 = 20000
ABEC.Polars:SPL = {
MapAngleRange = 0,180,37
NormAngle = 5
Distance = 2
Offset = 0
}
Report = {
Title = "horn example"
Width = 1600
Height = 900
}
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So, could someone confirm this will fit the BMS 4552?
STL file: https://at-horns.eu/ext/BMS4552-plug.zip
(Sanding down the tip is necessary.)
STL file: https://at-horns.eu/ext/BMS4552-plug.zip
(Sanding down the tip is necessary.)
The final verification of the 4554 adapter on my side. This is what you can expect when everything is fine.
You need to hear that 🙂
I did put some effort into sealing the mounting flange this time. In a design this clean, every detail matters.
I'm pretty curious how the frequency response below 1kHz will look like with the other BMS drivers.
Measured across the listening window:
You need to hear that 🙂
I did put some effort into sealing the mounting flange this time. In a design this clean, every detail matters.
I'm pretty curious how the frequency response below 1kHz will look like with the other BMS drivers.
Measured across the listening window:
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Nothing, I just did it according to my own guidelines 🙂
The surfaces are still far from perfect though. Wonder what difference can this make.
The surfaces are still far from perfect though. Wonder what difference can this make.
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To gasket is ok for testing various adapters. For a final build I would really prefer a glue-solution.
There just must be something compressible in the whole assembly. It's up to you where you put it, but this seems as a good place to me.
So is this adapter and the 4554 your current favourite? Before those 4554s disappear from the market 😉
A completely different topic: I appreciate a lot what has been created within this thread. Unfortunately we have now 827 pages and it gets nearly Impossible to search through them in order to find some of the valuable examples by mabat and some other users.
Just an idea: chatgpt with scraper plugin seems to be able to search through websites and collect requested data. Has someone here maybe the paid version and is interested in trying this? A collection of examples would be great.... Even if there will be quite some outdated ones or some not anymore compatible with current ATH version.
What do you think?
Just an idea: chatgpt with scraper plugin seems to be able to search through websites and collect requested data. Has someone here maybe the paid version and is interested in trying this? A collection of examples would be great.... Even if there will be quite some outdated ones or some not anymore compatible with current ATH version.
What do you think?
BMS 4554 - EQed response (simple IIR via Hypex FA123) and a burst decay.
Make the adapter as sturdy as possible. I guess there's still some avoidable ringing. It's definitely possible to feel vibrations of my (basically hollow) prototype print when touched.
And a quick sweep in HOLM:
2nd harmonic:
3rd:
4th:
Make the adapter as sturdy as possible. I guess there's still some avoidable ringing. It's definitely possible to feel vibrations of my (basically hollow) prototype print when touched.
And a quick sweep in HOLM:
2nd harmonic:
3rd:
4th:
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If you find the time to measure distortion with acoustic LR24 in place at 600 Hz, would be interesting. Are the levels correct ca. 90 dB?
Is it made with rosse or osse or something else?
That's a pure OS-SE.
I'm going to measure the Audax TW034 until the end of the year. Already have the waveguides ready.
I'm going to measure the Audax TW034 until the end of the year. Already have the waveguides ready.
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