New 12" horn |
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smoore
Young Croc Joined: 30 March 2011 Location: N.Devon Status: Offline Points: 937 |
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Posted: 03 July 2020 at 5:05pm |
Hi guys, havn't posted any of my projects on here before really but quite pleased with this one. It's a new 12" horn I've developed just after finishing my acoustics degree in Salford.
Overall dimensions are around 63wx60hx84d for the horn but will eventually include some space above for a compression driver and horn. I got a copy of COMSOL from uni which is a multiphysics platform that does really good FEA which predicted a reasonable response from 150Hz - 2kHz. I didn't simulate much lower or higher but will get it out on the next calm day for some measurements to see whats going on and make any appropriate mods. Here's the COMSOL simulated results. Some SPL and the model setup to see how it was done. There are several ways of doing this and i'm unsure if this is the best yet but it's a tricky art making FEM models that don't take days to compute results. We'll see how this compares! |
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smoore
Young Croc Joined: 30 March 2011 Location: N.Devon Status: Offline Points: 937 |
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Here's some piccies of the build of the prototype. Unsure whether I'll need to add some extra bracing to the horn as it definitely vibrates slightly when the level is turned up. Future builds will use a little thicker ply for the struts and the bracing. Also probably 2 layers of ply (though if this is braced well enough it shouldn't need it).
Initial testing seems to sound really good! There's definitely a dip from 1.8-2khz but it seems to play quite well running up to 2.8khz without any noticeable beaming. I was aiming for 40x40 or 60x40 dispersion but will see what the measurements tell me when I can get some. Excuse the mish-mash of wood types. This was all made from spare parts! The current driver is the beyma 12p80ndV2 but the simulated driver is the 12mi100 of which i'll be getting hold of soon. They shouldn't be a mile apart in terms of response, I just had a spare 12p80 around to use in the meantime. Dog for scale... Sitting ontop is a beyma td64 horn (i think) and a beyma cd10fe. Underneath is a BMS 15s430v2 in a 40hz reflex. |
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fatfreddiescat
Young Croc Joined: 15 October 2010 Location: N.E.Wales Status: Offline Points: 1081 |
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Well done for completing your degree, I would have loved to have done a degree in acoustics but life took a different path. have you by any chance come across this thread on DIYAudio:
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smoore
Young Croc Joined: 30 March 2011 Location: N.Devon Status: Offline Points: 937 |
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I had not seen that before but looks really good! Will have a look and hopefully a play next week! Thanks, it was a really varied interesting course well worth the time. It's just a shame (according to my tutors) I don't want to go into acoustic consultancy like they all did where all the money is!
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fatfreddiescat
Young Croc Joined: 15 October 2010 Location: N.E.Wales Status: Offline Points: 1081 |
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I've been following this thread fromhe beginning, a proper gold mine of info, Patrick Bateman has done a lot of work analysing and producing various waveguides that are worth a look.
In the early day's I nearly started a degree course in electronic engineering, just happened to get chatting to the course leader about audio stuff I was playing with, I had been told that one of the lecturers hobbies was designing horns, thought I would try and track him down as I was in town to collect some books from the library on acoustics etc, I would order, wait 6 weeks until they arrived and take a 4 hour round trip bus ride plus a six mile walk to collect them, managed to get a 9600 modem around then to get some more stuff to read, then a well paying tour landed on my plate, short of cash and headed off, loved it but don't mix too well when kids came along. Good times though.
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fatfreddiescat
Young Croc Joined: 15 October 2010 Location: N.E.Wales Status: Offline Points: 1081 |
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PS, nice work on the build, somehow missed your updates when I posted
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madboffin
Old Croc Joined: 03 July 2009 Location: Milton Keynes Status: Offline Points: 1537 |
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Using the dog as a phase plug, that's a new one... Doesn't all that curly fur have have too much acoustic absorption?
Edited by madboffin - 04 July 2020 at 9:57pm |
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smoore
Young Croc Joined: 30 March 2011 Location: N.Devon Status: Offline Points: 937 |
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He does add a lot of absorption but now the horn has Dual Woofers
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smoore
Young Croc Joined: 30 March 2011 Location: N.Devon Status: Offline Points: 937 |
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So I had a day of calm winds and got a few measurements! The vertical axis displayed a fairly quick roll off on the HF but on axis, this was measured around 4m from the cabinet with the mic on the floor.
Original plan was to not include a phase bung, but the next step now is to try and either mess withe throat to increase the HF between 1-2k or design a phase bung! My friend has just acquired a small CNC so that gives me a lot more options...
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Contour
Young Croc Joined: 03 March 2004 Status: Offline Points: 620 |
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Your FEA model seems not so accurate yet...
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smoore
Young Croc Joined: 30 March 2011 Location: N.Devon Status: Offline Points: 937 |
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So it would seem! A learning curve as per with anything new.
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LjudLahger
Young Croc Joined: 31 July 2008 Location: Sweden Status: Offline Points: 838 |
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