Acoustic Horn Design - The Practical Way

To those experienced with 3D printing, would you find it feasible to print a shell of a waveguide mould from several parts glued together? My idea would be to print a central part around the throat and several pieces around that. Even a small printer could be capable to print quite large moulds this way. I would generate STLs of the individual parts right from the program. This would be just the shell to get the shape, the interior would need to be filled.
 
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To those experienced with 3D printing, would you find it feasible to print a shell of a waveguide mould from several parts glued together? My idea would be to print a central part around the throat and several pieces around that. Even a small printer could be capable to print quite large moulds this way. I would generate STLs of the individual parts right from the program. This would be just the shell to get the shape, the interior would need to be filled.

This is absolutely possible and roughly my idea as well. But I was thinking of doing an "inverted" 3D model as a mold that I print, to build upon with glassfiber and polyester or something like that. 3D printing is fine for smaller pieces but to glue bigger pieces together and then use it as a final horn can be tricky if not sanded and finished off with some filling and paint. Hope I understood and answered your question. Just tell me otherwise :)

With some trial n error, a good printer and some time on your hands you could definitely print a complete horn. Either in parts or as a whole with a bigger printer. Worth checking out prices if other print for you, isn't always that expensive. Also check with your local Makerspace (if there's any in your town) if you can use their printers if you want to try yourself.
 
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I wanted to do something similar - not a mould but a full horn from pieces. I volunteer as the printer. If PLA is enough, I can print the parts for you to try out. My smaller printer is 180x180x180 mm and the larger is 260 diameter x 350 mm delta style.

Edit: I already printed a few things in parts - if proper orientation is possible, it is not a problem - best if no supports were needed.
 
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In the meantime we are progressing on Tritonia baffles (milled from a solid MDF block) -
 

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HF1440 is worthing some 650 to 750 XO in order to be married to a Faital 15PR400 - 2 ways in mind JBL M2 for "poors". However as a noob I don't know if those frequencies as cut-offs are suited to a 15" off axis ?


Do you plan to provide cnc/sell readymade/accept donation for a ready made horn/front bafle for the non hand gifted?


I don't know for others but at listening position in a home - average 3 to 4 m-, whatever the constant directivity took in equation, a good spl curve should be close since 200 hz -below is the room domain mainly- :
200 hz to 1500/2000 hz flat then dive to reach -3 to -5 dB at 3000 hz to 4200 hz then climb again to a plateau from 5000 hz to ? 15K hz that is a little lower than the 200hz/2000 hz (-2dB ?)?. Basicly at listening position imho a speaker is sounding better with a -10 dB between 80 hz to 20 k hz... in a more simple shape.


The HF1440 could easily acheive that from 500/600 - but I surmise 750 hz will be cooler for a horn not to be too much width huge- if the little coqueterie 1000/4000 hz can be flated/diged... or electronicaly EQed - but bye bye cool 2 way passive crossover- :)


However I'm sure some acoustics PhDs have their own more universal receip as far we talk about spl curve...
 
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It's not that difficult to EQ with a passive filter, I've done it many times. All that is needed are reliable measurement data (SPL polars and electrical impedances) and a good/convenient crossover simulator (and some experience, perhaps). There are no plans about selling anything right now. We are working on the prototypes so we'll see how it turns out...

I'm not too fond of using 15" anymore - they are actually quite big for home use. I'm more comfortable with 12". It's all about matching the radiation patterns around crossover frequency and there is quite a freedom in that once you have a good waveguide to begin with. If perfectly possible to match a 12" at 700 Hz as well.
 
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I assume that most bumps -or at best : flatiness- seen in the 1k to 4 hz commercial horns could be flated with a R//C or notched with a R//C//L .... but that's always passive component where the ears are so sensible... hence physical acoustical correction as you work on...
 
Frankly, passive components are maybe the last place (just before cables) I would look for audible degradations. I think that once you don't use a complete junk, it's just fine. At least no one ever showed me otherwise.

- As for the offering, I'm more thinking about vacuum forming. That could make lightweight waveguides that could be sent without extensive shipping costs and another shipping-related problems. But this would be strictly DIY with still a lot of subsequent manual work.