Acoustic Horn Design – The Easy Way (Ath4)

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mabat

mabat

Member
Joined 2004
at-horns.eu
Basically, yes, to get what you want.

- Does anyone have an experience with rough waveguide surface? There's a company here able to 3D print from (resin-impregnated) sand. They use a hi-tech professional equipment mainly for mold printing. I'm seriously considering trying it out (15" WG for about 200 EUR/piece). Of course they could also cast from aluminum right away (~600 EUR/piece).
 

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TNT

TNT

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Joined 2003
Paid Member
Prices seem fair. How about multi price? Thinking group buy here... Shipping costs?

If one paint that and sand it down where the sand starts to show... should give a smooth surface. And yes, surface finish vs. sound? Really, isn't that "imagined"?

//
 
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onni

Member
Joined 2013
lbstyling said:
What I always wanted was a narrow CD. Less than 50 degrees before dropping 6db+.

50 degrees is really quite a wide area when it's drawn out in my living room, and would cover several seats, but this would also:
-Keep efficiency high (smaller radiating area)
- Allow reflections to have the same spectrum to on axis, but at a much reduced level making imaging excellent for the direction of voices.

Alas, such a horn in 1.5 inch with a low crossover is unicorn poo.
Click to expand...
I'm quite certain that this is achievable. What is your definition of a low crossover?

Here is results from my simulation of a 320x198 mm horn I intend to 3D-print for a 2" fullrange driver (Peerless 830970):
900343d1607496002-acoustic-horn-design-easy-ath4-cs27-0-150-polars-png

The lines are spaces with 7.5 degrees. So at 2 kHz -6 dB is at about 34 degrees and at 5 kHz it's at about 28 degrees (both with 15-degree as reference).

/Anton
 
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454Casull

Member
Joined 2004
mabat said:
Basically, yes, to get what you want.

- Does anyone have an experience with rough waveguide surface? There's a company here able to 3D print from (resin-impregnated) sand. They use a hi-tech professional equipment mainly for mold printing. I'm seriously considering trying it out (15" WG for about 200 EUR/piece). Of course they could also cast from aluminum right away (~600 EUR/piece).
Click to expand...
Do they give any strength values for that material? Seems like it could be somewhat weak and brittle.
 
mabat

mabat

Member
Joined 2004
at-horns.eu
That's for a raw print alone, i.e. for molds. I guess that the epoxy resin impregnation (not a standard treatment) makes it pretty strong - "as a stone", they say.

Some more photos:

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An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
 
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kipman725

kipman725

Member
Joined 2007
Paid Member
This looks very promising and price competitive with other construction methods for large waveguides. Whats the actual machine like that makes these? some kind of 3d printer? Can this also be used to directly make a unity horn from a 3d model? maximum dimension of 1800 x 1000 x 700 mm is huge!
 
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Pasi

Member
Joined 2011
I'm contemplating about getting a BIG 3D printer capable of over 1m3 prints. Would there be takers for big horns and such if I offered to print them at reasonable rates? They won't be "free" but should be affordable in price. Especially if making multiples of same horn for several people.
 
Patrick Bateman

Patrick Bateman

Member
Joined 2006
Pasi said:
I'm contemplating about getting a BIG 3D printer capable of over 1m3 prints. Would there be takers for big horns and such if I offered to print them at reasonable rates? They won't be "free" but should be affordable in price. Especially if making multiples of same horn for several people.
Click to expand...

My experience has been exactly the same as Jack.

In fact, after I upgraded to a large printer, I went out and bought another small printer. Because maintaining the temperature in the printing enclosure is so critical, and if the temperature varies, your print suffers significantly.

Big printers may be practical if you have the room and expertise to build an enclosure that can maintain temperature really evenly.
 
L

lbstyling

Member
Joined 2008
onni said:
I'm quite certain that this is achievable. What is your definition of a low crossover?

Here is results from my simulation of a 320x198 mm horn I intend to 3D-print for a 2" fullrange driver (Peerless 830970):

The lines are spaces with 7.5 degrees. So at 2 kHz -6 dB is at about 34 degrees and at 5 kHz it's at about 28 degrees (both with 15-degree as reference).

/Anton
Click to expand...

Interesting!

Do you have a spectrogram for this? I find it easier to evaluate relative performance on them.

I'm currently using a big JMLC 350hz horn that is just magical because (I think?) The DI is low. Listening to Bille Eilish whispering puts the hairs up on the back of your neck, and big scale orchestra is just more exciting than on other speakers.

But it beams so much at the top that it's frustrating to live with in an open plan house as I walk around.

I wonder if I can narrow the directivity of the bass driver to blend will a more constant directivity narrow horn rather than one that goes from wide at 500hz to narrow at 20khz

Low crossover for me would be 500hz. 1.5 inch throat driver 0deg exit angle. In my application I can go max 900mm wide (or so), depth about the same, bit less depth is better.

I can print any size really as I run a print farm.
 
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