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Old 9th December 2012, 02:31 PM   #531
xrk971 is offline xrk971  United States
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Quote:
Originally Posted by doubtingthomas View Post
Foam core seems a great idea, but to take this a stage further, has any one tried laminating sheets of corrugated cardboard to a thickness of say 18mm nd using that? I just fitted a flat pack kitchen for someone and ended up with a lot of the stuff, tempted to give it a go.
Go for it! When laminating, you have the possibility of adding a material in between that will damp vibrations (if that is what you want). I have laminated two sheets of foam core with dabs of plumbers putty spread all over and bonding together with hot melt glue (although any glue able to span gap will work - like acrylic caulking). It makes a very nice "dead" sounding panel great for front face if that is what you are looking for - something to sound more like MDF. I suspect cardboard will work fine if laminated. The neat thing with this approach is it is all open for experimentation and in the spirit of DIY fun. We can get serious and try modeling and such but there is something very satisfying with sitting at your kitchen table with a razor and building stuff that actually is very good sounding to the ears without making a lot of sawdust.
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Old 9th December 2012, 02:38 PM   #532
xrk971 is offline xrk971  United States
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Quote:
Originally Posted by Don Hills View Post
The mouth of the "inner" horn is connected to the throats of the "outer" horns at node 7. The "outer" horns are two separate channels of different lengths. There is a significant discontinuity (area change) where the three horns join, which will cause significant reflections at that point. I thought it was poor drawing, but the drawing in the patent shows the same discontinuity so I'll assume for the moment that it is deliberate. There is no "leak" at the join, AkAbak accurately models such joins..
Don Hills,
Thank you for being so helpful with your answers. I have never used Akabak before, is there an instruction manual, tutorial, or thread you can point me to? I don't even have the software installed yet. Complete newbie with Akabak, any more tips you have would be greatly appreciated. It does sound like the model incorporates the bifurcation then. What do you think happens to a brass horn (like a trumpet) that has a bifurcated path and two bells? I think the sounds would oscillate between one and another - rather than divide evenly. It would be interesting if MJK picks up on this and mods his Mathcad sheets to incorporate multiple paths - right now it is strictly one path and you can do things like Planet10 suggested to "fool' it to thinking it is multiple paths like how Sachiko was modeled.
Thanks again.
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Xrk971
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Old 9th December 2012, 02:38 PM   #533
6L6 is offline 6L6  United States
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If you bond the laminations together with PVA wood glue or some other wood/construction adhesive, It is going to be impressively strong.

I would suggest paying particular attention to how you bond the edges of the cardboard to whatever you are gluing them to -- as those edges have very little surface area. You might want to use PVA glue as well as hot melt - the hot melt will put it in place, and the PVA will then have time to set properly.

Please report back with any information you have whilst trying your idea!

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Old 9th December 2012, 02:42 PM   #534
xrk971 is offline xrk971  United States
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Quote:
Originally Posted by SprockeT1597 View Post
yes, that was my main reservation in this prospect. Especially using a 6X9, but I thought if i can do it cheap enough, I might at least learn something. so its function over form!




Yes I agree about the beauty of the square design. but I though seeing as ive already violated that with a 6X9 may as well keep going! Ive been roughing something up in blender. Ignoring all theory of horn design and just concentrating on "6 BY 9"... Also thinking about doing it first in paper mache, because it would be a waste of foam core!

But thankyou for giving my drunken idea purpose!
I really think you out to give the rectangle a try. One great reason to do so is the fact that the stock foam core boards from the dollar stores come in a 20 in x 30 in size. Is it sheer serenditpity that it is in the 2:3 aspect ratio? Just scale the drawing to 20 in x 30 in at a reprographics store, align it in such a way to equalize the long and short paths as Dave (Planet10) suggests - there may be something acoustically magical waiting for you. The 6x9 speaker will have a lot of bass, if you happen to have the car audio variety that has coaxial tweeter, even better! I might have to try this myself... The design may have to be modified with a box that is large enough to accommodate the 6x9. You can do this by placing a riser box above the main speaker box hole and have a raised driver section. Otherwise it would have to be scaled much larger to hold 6x9 inside the main cavity. See scaled picture in 2:3 proportions.
Good luck.

Last edited by xrk971; 9th December 2012 at 03:12 PM.
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Old 9th December 2012, 03:14 PM   #535
xrk971 is offline xrk971  United States
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Here is Planet10's plan but scaled to 2:3 aspect ratio.
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File Type: jpg 2x3-cornu-horn-grid.jpg (61.2 KB, 500 views)
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Old 9th December 2012, 03:53 PM   #536
xrk971 is offline xrk971  United States
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The Zen Acousta design might be worth a try in foam core

Zen Acousta
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Old 9th December 2012, 06:35 PM   #537
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Just scaling to a rectangle will not work. Don's comments suggest that even the square needs work in terms of smoothing the expansions, stretching in one direction will yield horn paths that actually get smaller in places.

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Old 9th December 2012, 08:32 PM   #538
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Quote:
Originally Posted by xrk971 View Post
... I have never used Akabak before, is there an instruction manual, tutorial, or thread you can point me to? I don't even have the software installed yet. ...
Read all of this thread:
Akabak Simulator

Note my "AkAbak for the cognitively challenged" posts.
Go here for the software: R&D-Team - Software Development

There's a manual and a set of worked examples included in the package.

Quote:
Originally Posted by xrk971 View Post
... It does sound like the model incorporates the bifurcation then. What do you think happens to a brass horn (like a trumpet) that has a bifurcated path and two bells? ...
I don't know, but it's easy enough to simulate with AkAbak.
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Old 10th December 2012, 12:13 AM   #539
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ok, finally able to get online at work with my phone and laptop. heres some pics of my current project, nearly finished too.

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Old 10th December 2012, 05:31 AM   #540
badman is offline badman  United States
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Clever design klampy. I like the distortion and (very modestly) force cancelling layout.
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