Acoustic Horn Design – The Easy Way (Ath4)

[turk 182]

Sure. It's just seems to hold true no matter what we do.

can't cheat physics...as to hearing 15k at my age it would need to be loud!! and even when i was younger i never deluded myself into thinking that hearing that high was useful because all that happening there is little more than harmonic spectra.

 

[mabat]

can't cheat physics...

Sometimes it can be done, like with the ESP

 

[jzagaja]

Was ESP measured eg with 2-4" FR unit? (eg. Faital Pro 4 FE 32 B)

 

[turk 182]

ESP??

 

[jzagaja]

ESP+waveguide

 

[turk 182]

sorry, what is "ESP"? i'm not familiar with the abbreviation.

 

[tmuikku]

External Shaping Plug, convert flat wavefront to spherical.
See link few posts back, by mabat https://www.diyaudio.com/community/...-design-the-easy-way-ath4.338806/post-7087129

 

[jzagaja]

I would like to help in this thread e.g. scan surface of 5FE120 and make ESP plus waveguide of your choice and measure.

 

[TNT]

Isnt that a little too big? How about 3FE22?

//

 

[jzagaja]

5FE120 I have in hand. Others must buy.

 

[mabat]

For those willing to print it and try, here's a modified ST260. This outer shape is actually the direct result of the formulas used. I have also a version with a truly round (flat) mouth but this performs better so I left it as it is.

STL for download: https://at-horns.eu/ext/ST260-BLD-mres.zip

 

[tmuikku]

Pardon asking, been following with left eye only, whats the benefit with the throat pinch?

 

[mabat]

Just an experiment.
These are the predicted horizontal polars 2k - 12k

 

[tmuikku]

Yeah response seems good, but it has been good for moons ago so thought I've missed out something its cool looking device if nothing else

 

[mabat]

Vertical polars -

And horizontal again

BTW, I haven't checked but I don't think the throat is really "pinched", as the area is probably still only expading.

 

[tmuikku]

Smooth as butter and all the way to 180 degrees I assume, couldn't be any better.
There is slight difference in horizontal and vertical coverage. Have you tried how much vertical could be narrowed?

 

[mabat]

Have you tried how much vertical could be narrowed?

It can't be narrower unless made considerably larger. That's not an option for a 10" device.
This is probably as good as it gets.

 

[mabat]

It kind of reminds me a multicell horn (actually two-cell in this case) but without any phasing issues. It's almost as if two waveguides were cut and put together.
An exaggerated example:

0-90/5:

 

[tmuikku]

Yes, could you "join" two 50x50 devices for example? just pushing it narrow vertical and wide horizontal coverage are almost exclusively made with arrays, very hard to make orher ways good. Would be nice if there was good waveguide for something like that.

 

[mabat]

I have absolutely no idea what it will do but I'm pretty sceptical - ABEC project attached.

BTW, all these shapes are composed of nothing but R-OSSE profiles - quite powerful tool, all simple formulas.