60x40 HF-Horn |
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JulianDA
Registered User Joined: 29 May 2018 Location: Soest, Germany Status: Online Points: 114 |
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Posted: 25 May 2020 at 4:13pm |
Greetings Folks,
while building the second one of my double 15" Kickhorn, i started the journey of designing and building my very first HF-Horn to learn more about this stuff and eventually design my own fully hornloaded 10/1 Midtop to sit above the Kicks. After countless hours of CAD Design and ABEC Simulations i reached a point at which it seemed feasable to try out a first Prototype. This is the Design that i came up with: Frontview Sideview Topview |
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JulianDA
Registered User Joined: 29 May 2018 Location: Soest, Germany Status: Online Points: 114 |
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The following Pictures show the polar-plots of my simulation with and without an infinite Baffle
First with the IB: Directivity horizontal in 6dB steps Directivity horizontal in 0,5dB steps Directivity vertical in 6dB steps
Directivity vertical in 0,5dB steps And now without the IB just because i did my measurements without any baffle (and yes, i know they look horrendous :D ): Directivity horizontal in 6dB steps Directivity vertical in 6dB steps |
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JulianDA
Registered User Joined: 29 May 2018 Location: Soest, Germany Status: Online Points: 114 |
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So after that, i started building the first prototype by 3D-Printing. Sadly there where some defects, but most of them just look ugly. The only really bad thing is the gap through the middle where i joindes the two halfs. But its nothing a little bit of hotglue cant fix :P. The result looks like this:
And with that first prototype i did some measurements with the Faital HF100 as the driver (just because it was laying around in the basement)
Because of limited Space i did the Measurements indoors at 40cm distance in 15° steps. First i measured the raw frequency response without Eq or smoothing, then i did some Eq-settings to get a flat on-axi response and did the measurements again. Raw FR without smoothing (0-60°) A little bit of Eq-magic on axis and 1/3. Octave smoothing FR horizontal 0-90° with 1/3. Octave smoothing To me this looks promising and now i want to try and build this Horn out of fiberglass. For that i ordered some fiberglass sheets, resin, moldrelease wax and gelcoat. My plan is to make a negative mold out of plaster (thats why i printed it in two halfes) and mount that on a wooden bit that represents the mold for the flange. Then i wanted to apply the moldrelease wax, then the gelcoat and then apply the fiberglass. But i obviously have no previous experience with constructing horns out of fiberglass. Is there somebody that could give me some tips or maybe tell me some common mistakes that people make? I appreciate all of your input! Cheers, Julian |
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fatfreddiescat
Young Croc Joined: 15 October 2010 Location: N.E.Wales Status: Offline Points: 1082 |
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Looks like some really nice work you've done and lookforward to seeing more as it develops, thanks for posting, I'm not sure if you have seen this thread on diyaudio:
https://www.diyaudio.com/forums/multi-way/338806-acoustic-horn-design-easy-ath4.html |
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VECTORDJ
Young Croc Joined: 11 June 2006 Location: United States Status: Offline Points: 515 |
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I have not used 3d printing...but why not print the horn/wave guide as one piece????
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FOO
Young Croc Joined: 23 December 2018 Location: Denmark Status: Offline Points: 815 |
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If he's using a printer with a small bedding, that sets some physical limits. But it should not be a problem doing it in one piece if the bedding size allows it 🙂
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JulianDA
Registered User Joined: 29 May 2018 Location: Soest, Germany Status: Online Points: 114 |
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I printed it in two halfes so i can use it as the mold for the negative form i will make out of plaster (and to save a little on the material used for supporting the overhangs). My problem was just that my room was too cold while i printed the second half...because of that the print had more internal stresses from cooling and warped a little bit at the place where both halfes join. But i dont think that this will cause problems. We will see how it wents when i try do build it with fiberglass. I will keep you updated ;) Edited by JulianDA - 25 May 2020 at 9:20pm |
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JulianDA
Registered User Joined: 29 May 2018 Location: Soest, Germany Status: Online Points: 114 |
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Thank you! And no, i had not seen this topic...i will look into it. Thanks again :) |
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bob4
Old Croc Joined: 29 February 2004 Location: Finland/Germany Status: Offline Points: 1843 |
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That print looks very good! On diyaudio.com someone else was 3d printing horns and had a lot more problems with cracks and warping......
If you oversize the print to have a bit of extra waste material at the edge, you could sand the edges of the two halves flat on a stone or glass slab with sandpaper glued onto it, to get a perfect fit without gaps. But i suppose fiberglass will be much stronger in the end.
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odc04r
Old Croc Joined: 12 July 2006 Location: Sarfampton Status: Offline Points: 5482 |
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I think is the DIYaudio thread you might be thinking of, a very large 2 part print for a unity horn mid-high segment, there's discussion of how some issues due to print bed induced warping etc were fixed due to the size of the prints
https://www.diyaudio.com/forums/multi-way/312414-3d-printed-3-unity-waveguide-home-audio-speaker.html I've always wanted to do something similar, and I have access to an ultimaker with a decent bed size. But there is always something else first, it's quite far down the project list. Nice work though, always enjoy seeing designs come through simulation then a CAD/CAM workflow to reality. |
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Jo bg
Young Croc Joined: 08 March 2017 Status: Offline Points: 552 |
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Very nice work, thanks for sharing!
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Jo bg
Young Croc Joined: 08 March 2017 Status: Offline Points: 552 |
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What's the size?
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