Acoustic Horn Design – The Easy Way (Ath4)

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#16,282
Any experience with Audax TW034 dome on a waveguide?
It's a soft dome, hence may not work so well so high as a hard one, but its shape/height seems promising for a wide beamwidth, and the faceplace is just calling for it -

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Based on the photo it's at least 10mm tall.
 
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#16,283
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#16,285
It needs to be optimized, will hardly work well with a "stock" waveguide, but then it's like a miracle (the taller the dome the better - for a wide dispersion a tall 34mm is better than a shallow 25mm) -

mabat

Post in thread 'Acoustic Horn Design – The Easy Way (Ath4)'

BTW, I also tried some variations on the T34A theme and it seems that +-65 deg is really the limit above ~12 kHz with the bare tweeter...
It's no problem to have +-70deg below that.

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#16,286
TNT said:
... so all domes rely on bending wave "break up" for its dispersion I would think..
Click to expand...
They just beam, that's what happens. By adding a (surprisingly shallow) waveguide this can be changed completely. But you need the dome to maintain its pistonic motion, at least for a simple rigid-boundary modeling that we use. That's where a stiff dome like the T34A comes handy. With the Audax, we would have to try, I guess. For that money I would be happy with 12 - 15 kHz, don't need 20 🙂

But let me repeat, as this is crutial:
The taller the dome, the better - for a wide dispersion, a tall 34mm is better than a shallow 25mm.
 
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#16,291
The larger 1.1" soft domes from Sica look kind of tall here on the photos:
https://www.dibirama.it/home-page/tweeter/377-sica-lp90-28-n92-tw-tweeter-1-1-8-ohm-120-wmax.html
https://www.dibirama.it/home-page/tweeter/601-sica-lp110-28-380tw-tweeter-1-1-8-ohm-120wmax.html

I'm sure they would send you CAD models. (They kindly sent me a model of this driver when inquired https://sica.it/prodotto/2-h-08-sl/ About the same Sd as a large dome, FR looks decent for eq, but haven't done much with it yet.)
 
#16,292
The downside of the smaller domes is that the surround typically occupies a relatively large area compared to the dome itself. That's never a good thing and it's also where the bigger domes have a significant advantage. But it's certainly a good tip, I think I even have the LP100 somewhere. I can look how easily it could be attached to a waveguide. It's interesting that the published data don't even suggest it should work, but perhaps the default factory "waveguides" are too small to have the desired effect. Or maybe the soft domes just don't make it possible - we'll see, I already ordered a pair of TW034.
 
#16,298
How about the WG throat covering the surround, fully or partially. (So that the throat diameter is closer to the dome/voice coil diameter and starts a fracton of a mm above the surround. Besides that it creates a cavity, but the output of the surround is less to begin with.) Or in the partial case covering the surround kind of in a radial phase phase plug fashion https://www.desmos.com/calculator/aajs8hkfim and would be "blended out" as it expands.
 
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#16,300
I tried to cover the surround in different ways in the sims, but it always came out worse than without. Maybe I just didn't have luck, but I suspect that these little details are not easy to model reliably (and that it's probably worse in the sim than in reality). That's my takeaway at the moment - these experiments would need to be done hand in hand empiricaly with real devices, to see what it actually does.
 
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