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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)

norman bates 13th February 2020 04:51 AM

post 993.

the graph on the right (when 2 graphs shown), that is the non knuckles ?

Response looks really good to me (compared to so so much) on the non knuckles.

what are the graphs, left to right again ? vertical, horizontal, diagonal ?

mabat 13th February 2020 09:22 AM

Quote:

Originally Posted by cowanaudio (https://www.diyaudio.com/forums/multi-way/338806-acoustic-horn-design-easy-ath4-post6082289.html#post6082289)
Try measuring a bare compression driver, they show significant pattern control above 10KHz. How can a waveguide without a diffraction slot make this wider? I'm assuming your "waveguide done properly" does not have a diffraction slot.

Oh no, we are back at this again :D

OK, I just quickly simulated the following two cases:
a) 175deg OS waveguide, i.e. almost a flat baffle, which is really the limiting case for an OS waveguide as coverage angle approaches 180deg;
b) 90deg OS wavaguide.

The pictures will follow...

mabat 13th February 2020 09:23 AM

2 Attachment(s)
A "flat baffle" case (175deg coverage):

mabat 13th February 2020 09:24 AM

2 Attachment(s)
90deg waveguide:

(Both cases for 1" throat.)

mabat 13th February 2020 09:26 AM

2 Attachment(s)
Since the flat baffle is the limiting case for an OS waveguide as the coverage widens (up to 180deg), there must be a continuum.
Any comments or suggestions?

- Does anyone know how to thicken the plot lines in VACS?

mabat 13th February 2020 10:02 AM

Quote:

Originally Posted by fluid (https://www.diyaudio.com/forums/multi-way/338806-acoustic-horn-design-easy-ath4-post6082058.html#post6082058)
Seems the over 10K response is smoother without the big dip in the M2 clone, could you extend the sim to go to 20K to see it better?

I can but it makes a huge difference in BEM running times. I try to limit the mesh resolution as possible to speed things up. There's still a lot to look at and improve between 1k - 10k. IMO, there's too many unknowns above 10 kHz that it makes little sense to try to simulate it this way. I can try occasionally. This might be an interesting case.

mabat 13th February 2020 10:10 AM

2 Attachment(s)
120deg OS waveguide -

mabat 13th February 2020 10:21 AM

Quote:

Originally Posted by norman bates (https://www.diyaudio.com/forums/multi-way/338806-acoustic-horn-design-easy-ath4-post6082387.html#post6082387)
post 993.

the graph on the right (when 2 graphs shown), that is the non knuckles ?

Yes.

Quote:

what are the graphs, left to right again ? vertical, horizontal, diagonal ?
Yes. The graphs are labeled "SPL_H / SPL_V / SPL_D" accordingly.

mabat 13th February 2020 10:57 AM

2 Attachment(s)
...some may be waiting for 60 degrees :) (Mind the scale shift.)

mabat 13th February 2020 11:47 AM

2 Attachment(s)
60, 35 mm driver exit. Up to about 15k it's virtually without a change compared to 1".


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