Acoustic Horn Design – The Easy Way (Ath4)

[Ro808]

Originally Posted by mabat

BTW, that shape is simply a result of the way they allowed the profile curves to change, which was very basic and still quite limited rule, IMHO (just bezier cubics, IIRC). So it is optimized in a sense that it may perform "best" within the limitations given. Which is of course true for any such optimization. Anyway, good luck with that!

Agreed. In the last 10 years we have seen horns with knuckles, mumbs, ridges and so on. Neither of these features has resulted in an evolutionary performance improvement.

[mabat]

Originally Posted by Ro808

... Neither of these features has resulted in an evolutionary performance improvement.

And that would be...?

[Ro808]

You're smart enough to come up with some desirable features, but to give an obvious example:
- Elimination of interferences.

[mabat]

No I really tried to imagine an evolutionary performance improvement in horns but really can't think of any. Maybe that's also the reason I won't ever come up with any

Interferences? Well, I "could" imagine a driver+horn combo reaching a pure spherical wavefront - that would be an improvement!

[gedlee]

Someone is confused, maybe me!

Ro808 stated:

Neither of these features has resulted in an evolutionary performance improvement.

Which, to me, means that these features have not resulted in any improvements.

but Mabat says:

No I really tried to imagine an evolutionary performance improvement in horns but really can't think of any.

Which says, to me, the exact same thing.

Do you guys agree or disagree? It's not clear.

Interferences? Well, I "could" imagine a driver+horn combo reaching a pure spherical wavefront - that would be an improvement!

I too was unclear what was meant by "interference".
And yes a "pure spherical wavefront" would be great, but you should also state that this should occur across the bandwidth. A spherical wavefront at one frequency is not so difficult, but at all frequencies, it is likely impossible.

[mabat]

This is funny. We agree about the improvements (there have been none). But Ro808 says he's sure I'm able to come up with some ideas what the possible improvements in horns could be. And I say I'm really not...

[mabat]

This is also funny: Today, solely by mistake, I tried something I didn't want (what could be considered as an error), but hey, the result is one of the best I have seen -

[mabat]

Now I know how to improve things!

[gedlee]

A flatter waveguide is always going to be smoother, but with less DI control. As the DI gets raised there will be more problems. My goal has always been as high a DI as I can get in a reasonable configuration and this always leads to tradeoffs.

[Dmitrij_S]

Originally Posted by mabat

And that would be...?

I suppose, revolutionary improvement would mean

* Flat acoustic loading from 200-300Hz and up to the last audio octave (e.g. like Heavise or step Sigmoid function).
* Constant directivity in the same frequency range. (I suppose beamwidth of -+(20-30)° in all directions would be ok, at least for home audio).
*Horn-related acoustic nonlinearities would be comparable to that of the direct radiator.
*Perhaps, some kind of numerical criterion should specify a minimum value of HOMs amount.

"Revolutionary design" should improve all the point above at the same time. But as we know, "the horn reality" is completely different. Numerical optimisation helps to find a certain balance of contradictory horn parameters .