Acoustic Horn Design – The Easy Way (Ath4)

[TNT]

Exactly!

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[mabat]

I bet non-parallel walls has a positive impact on HOM dampening.

I still don't know how to isolate those in a clear way but to me the latest results indicate that the cross-sectional shape (per se) is basically irrelevant in the end. If at all, it will probably be a (very) HF stuff - hard to simulate accurately anyway.

 

[TNT]

Yes - perhaps one need to go to the next level of physical simulation to nail the HOMs... and to see any other difference re: parallel walls...

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[AllenB]

Ok, so you rearrange it but it's still delayed and everything else that goes with diffracted energy.

 

[mabat]

But we already know how to make horns where diffraction is not an issue. Whether is it round or rectangular at the mouth seems to make very little difference.

 

[mabat]

Exactly!

I just don't follow.

 

[TNT]

By reflecting the wave "away" and make it meet other sized geometries, non parallel walls has a dampening/scattering effect making energy distributed rather than concentrated -> lower Qs in effect. No?

When you say diffraction above, you don't mean from the mouth I suppose?

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[AllenB]

The two rightmost walls in #10,260 are parallel, unless that's what you're saying?

 

[TNT]

The only 2 parallell walls I see in your picture are between the same color indicated lines...

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[AllenB]

The walls in red are parallel from the point of view of the mode in green.

 

[mabat]

A horn is driven at the throat and the sound wave develops from there. So a rectangular horn is less "coherent" (i.e. with diffraction less concentrated in time and space) than a round one or a 7-sided one (the more sides, the closer it is to a circle, i.e. the more symmetric/coherent it is). That's the situation as I see it.

And because the simulations show that both rectangles and circles can give perfectly smooth results, I really don't see this as an issue. What's crutial is the profile and how it's terminated - that seems to make all the difference.

 

[TNT]

OK but that dont look like it could be a part of any "some"-agon?

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[TNT]

Yes of course most energy moves orthogonal to the walls we are discussing but HOMs is an energy that "appears" in the other direction - right?

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[AllenB]

OK but that dont look like it could be a part of any "some"-agon?

Lol. As it turns out I just folded a rectangle, once. The far-reaching implications should be obvious

 

[TNT]

Monkey Coffin Conundrum... Drum being the focus word there

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[mabat]

but HOMs is an energy that "appears" in the other direction - right?

Again, the worst should be a round horn in this regard. And the fact is that is not problematic at all - if done right. How could be worse something that's less symmetric?

 

[TNT]

I think an asymmetric would be better yes. But perhaps its not as easy as just how few segments... I do agree that more segments tend to be = round...

So perhaps the lest, uneven numer of sides?

3?

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[mabat]

3?

Could be
Four sides are already quite good though, even without a mouth folding back (that wouldn't work so well with a round horn).

 

[TNT]

But how to terminate (mouth) in a decent manner?

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[mabat]

That's the nice thing - because of the large asymmetry (compared to a round one), it's not really necessary (although it would surely improve it further).

From the construction point of view, it's no problem either - you can continue to bend the ply back as much as you want. With an octagon, I would definitely add such rolling back. With a rectangle, I would go without.