Actually I revisited the measurements, and it's a measurement where I tried to subdivide the throat with a "phase plug" without meanders, which caused weird stuff.
here are the two graphs that were supposed to be in that comparison.
Thank you for pointing out Fluid!
Red graph is the rectangular horn with no phase plug
Blue graph is the concentric horn with a phase plug.
I should really make a simple adapter without meanders, so I can present how the driver looks on that particular horn. I can also provide the impedance measurements, if that would be of interest to anyone.
I'm not sure how impressed I'm with the Axi2050... not sure how other owners feel about it.
I'll try to compare the driver used in the measurements with driver nr.2 which is still in it's packaging.
here are the two graphs that were supposed to be in that comparison.
Thank you for pointing out Fluid!
Red graph is the rectangular horn with no phase plug
Blue graph is the concentric horn with a phase plug.
I should really make a simple adapter without meanders, so I can present how the driver looks on that particular horn. I can also provide the impedance measurements, if that would be of interest to anyone.
I'm not sure how impressed I'm with the Axi2050... not sure how other owners feel about it.
I'll try to compare the driver used in the measurements with driver nr.2 which is still in it's packaging.
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You are welcome that my inability to read the graph scale was helpful
Could you gate to a higher frequency to cut out the room response and zoom in to the first few milliseconds?
Thank you for the report, I find that actually pretty encouraging!
How did you design the round horn? It's not the one I put into the DXF, is it. I ask because the match between the plug and the horn turns out to be quite critical. It certainly needs to be at least simulated, as it's not that easy to get it flat and smooth on axis, probably because it's already so large. But perhaps the plug itself has an effect as well (I would try to file off the vane edges at least at the throat to see if it has any effect). How thick are the plug walls in the end? Maybe some slight correction for this in the plug design should be incorporated as well.
It would be also interesting to see raw the measurements without any EQ to see the effect on efficiency on the lower end.
How did you design the round horn? It's not the one I put into the DXF, is it. I ask because the match between the plug and the horn turns out to be quite critical. It certainly needs to be at least simulated, as it's not that easy to get it flat and smooth on axis, probably because it's already so large. But perhaps the plug itself has an effect as well (I would try to file off the vane edges at least at the throat to see if it has any effect). How thick are the plug walls in the end? Maybe some slight correction for this in the plug design should be incorporated as well.
It would be also interesting to see raw the measurements without any EQ to see the effect on efficiency on the lower end.
Perhaps the measurement setup really deserves some cleaning up first - e.g. this looks strange to me, I see no reason for such behaviour as here around 5 kHz (the rectangular horn, 0 and 30 deg).
And I'll start thinking how to morph the plug into a rectangular shape, just to disrupt the symmetry a bit...
That would be awesome!
And I'll start thinking how to morph the plug into a rectangular shape, just to disrupt the symmetry a bit...
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I'll try putting some foam in between the phase plug of the driver and phase plug of the horn.
Physical measurement of the vane thickness coming up too.
I ****** up while milling the one you attached in the drawing, and didn't want to make a new one, so I used one I had in hand.
The one with the points is the contour you supplied
The blue one is the one I used.
I can see now that they are not exactly the same. (Looked like a match irl)
I'll take some more measurements of the driver alone and the plug later today and make a jig
Physical measurement of the vane thickness coming up too.
I ****** up while milling the one you attached in the drawing, and didn't want to make a new one, so I used one I had in hand.
The one with the points is the contour you supplied
The blue one is the one I used.
I can see now that they are not exactly the same. (Looked like a match irl)
I'll take some more measurements of the driver alone and the plug later today and make a jig
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I would say this is already quite a noticeable mismatch.
- Overall, based on the data presented so far, I would say that the (non-)flatness of the input wavefront is not an issue - it would look a lot (and I mean a lot) worse if it was an issue. And if there are still things to improve, these are in the details of the plug design/construction or in a better plug-horn coupling. I'm eager to try my own now
- Overall, based on the data presented so far, I would say that the (non-)flatness of the input wavefront is not an issue - it would look a lot (and I mean a lot) worse if it was an issue. And if there are still things to improve, these are in the details of the plug design/construction or in a better plug-horn coupling. I'm eager to try my own now
I would say this is already quite a noticeable mismatch.
- Overall, based on the data presented so far, I would say that the (non-)flatness of the input wavefront is not an issue - it would look a lot (and I mean a lot) worse if it was an issue. And if there are still things to improve, these are in the details of the plug design/construction or in a better plug-horn coupling. I'm eager to try my own now
I think it might be more of a construction issue.
There is still quite of an area the vanes and supports occupy at the start of the throat which 100% causes reflections.
Mabat, I'm considering 'sharpening up' the vanes on a lathe after printing. I'm not sure how to properly convert your dxf to sharp ends - could you post a model?
Or maybe I should go for a 5 vane 800mm diameter version straight away. It would be really fun to see what can be wrung out of the AXI at both ends.
Or maybe I should go for a 5 vane 800mm diameter version straight away. It would be really fun to see what can be wrung out of the AXI at both ends.
