Not quite the same but similar, this is "only" 810 x 567 x 340 mm:
I see a big hole on-axis around 7 kHz on this one, not sure it's real (may be a mesh size issue):
Otherwise it's pretty smooth and controlled, acoustic impedance of this throat arrangement being a bit untypical.
I see a big hole on-axis around 7 kHz on this one, not sure it's real (may be a mesh size issue):
Otherwise it's pretty smooth and controlled, acoustic impedance of this throat arrangement being a bit untypical.
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What's the probability that the hole on axis is in simulation only?Not quite the same but similar, this is "only" 810 x 567 x 340 mm:
View attachment 1075368
View attachment 1075369 View attachment 1075371
I see a big hole on-axis around 7 kHz on this one, not sure it's real (may be a mesh size issue):
View attachment 1075372
Otherwise it's pretty smooth and controlled, acoustic impedance of this throat arrangement being a bit untypical.
This is getting close to what I'm looking for. I would be aiming for wider pattern (+/-30deg at -1db) otherwise it's excellent for my use (assuming the 7khz issue is an artifact.)
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To verify that means going on the edge of possible using ABEC, the number of BEM elements rises quickly with such a large device. I don't have a very powerful machine...
- One can further reduce the number of mesh elements by making the rear surface flat (mathematical), i.e. smaller:
Mesh.RearShape = 2
- One can further reduce the number of mesh elements by making the rear surface flat (mathematical), i.e. smaller:
Mesh.RearShape = 2
The on-axis hole looks quite real (simulated on a little bit smaller version of the horn, 720 x 508 x 300mm) -
Normalized at 30deg:
My guess is that it would disappear with a smoother throat adapter.
Haven't tried the rings...
ABEC project attached. Someone might try to show a field observation.
Normalized at 30deg:
My guess is that it would disappear with a smoother throat adapter.
Haven't tried the rings...
ABEC project attached. Someone might try to show a field observation.
Attachments
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Here's my new Fusion360 script. It uses a new input file format (*.asc), commented example attached.This sounds like it would work with my bends as well.
It just imports sketches defined in the input file:
Then you can manually use the loft feature(s) or whatever:
ASC file format (ordinary text file):
The first number is always a command, the rest are its parameters (some of them may be optional).
Comment lines start with '#'.
Attachments
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Anyway, I think this could have a potential to make for a nice device overall. Worth pursuing further, IMO. Unfortunately an optimization of a full 3D mesh is very slow and it will take some time to get the most out of it. Perhaps a task for a collaborative effort?
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I'm going to give it a goAnyway, I think this could have a potential to make for a nice device overall. Worth pursuing further, IMO. Unfortunately an optimization of a full 3D mesh is very slow and it will take some time to get the most out of it. Perhaps a task for a collaborative effort?
That looks good!What about laminating using this?
View attachment 1075862
It's a paper 500 g/m^2, 800 x 1200 mm, 0.8 mm thick, 2 €/kg. Could be cut with scissors![]()
In fusion you can do sheet metal folding. It can be used to calculate the "projected" flat piece needed.
I was thinking about kerf bending plywood, but this looks good too.
I tried a couple of simulations today with different mouth aspect ratios, but it quickly deteriorates.
Could be nice to use an ESP plug before the throat adapter. Unless the horn is only to be used until 10k
Maybe some horizontal vanes could be inserted inside the adapter (made a part of it) to improve the vertical dispersion on HF. Horizontally I don't think that's needed - in the above example it makes a 50mm throat radiate as if it was 30mm or even better. The same can be done with a 36mm throat and get even better horizontal polars than with a 25mm driver (at 14 kHz it would look as 10 kHz above).
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The Electro Voice "TransPlanar™" horns used horizontal vanes in their diffraction throats, dispersion was quite good in both planes.Maybe some horizontal vanes could be inserted inside the adapter (made a part of it) to improve the vertical dispersion on HF. Horizontally I don't think that's needed - in the above example it makes a 50mm throat radiate as if it was 30mm or even better. The same can be done with a 36mm throat and get even better horizontal polars than with a 25mm driver (at 14 kHz it would look as 10 kHz above).
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