This is the thread I was thinking of.
http://www.diyaudio.com/forums/multi-way/106736-construction-journey-active-3-way-32.html
Take a look at post #318 from the OP and the attached barbecue photo. He was very persistent but finally had to admit defeat. No shame though. He gave it a good shot. The discussion may save a lot of wasted effort.
Here is the actual thread
http://www.diyaudio.com/forums/multi-way/159029-large-3-ways-design-build.html
The most promising lightweight panels I've actually messed with were with "ribs" like you might see in a boat hull or plane wing (and see one of in that thread), but not bothering with the curves, and open on the inside. This is why I mentioned earlier in this thread that maybe a grid of rigid foam between thin panels would be worth a try.
I haven't followed all the way through yet, though. I used the rib strategy to brace a large rear panel that wouldn't stop acting up and couldn't be cross braced, and it was COMPLETELY effective, but everything was 18mm plywood there, so not light by a long stretch.
Around the same time just for kicks while waiting for glue to try, I made a little panel out of 1/4" ply the same way but with a flat panel on each side of the "ribs" (the idea being that the ribs stiffen the panels to prevent LF vibrations, and the enclosed air gaps prevent transmission of higher frequencies). It sure seemed/felt/knocked like it would work, but I still haven't built a speaker that way and this was like two years ago. Usually when you want lightweight you also want to avoid extra size, and 5-8cm thick walls really make a small box big in a hurry.
I haven't followed all the way through yet, though. I used the rib strategy to brace a large rear panel that wouldn't stop acting up and couldn't be cross braced, and it was COMPLETELY effective, but everything was 18mm plywood there, so not light by a long stretch.
Around the same time just for kicks while waiting for glue to try, I made a little panel out of 1/4" ply the same way but with a flat panel on each side of the "ribs" (the idea being that the ribs stiffen the panels to prevent LF vibrations, and the enclosed air gaps prevent transmission of higher frequencies). It sure seemed/felt/knocked like it would work, but I still haven't built a speaker that way and this was like two years ago. Usually when you want lightweight you also want to avoid extra size, and 5-8cm thick walls really make a small box big in a hurry.
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Bon: yes, that is a bon-fire 🙂
dumptruck: interesting build(s). While I'm still stockpiling aluminum cans for a future build (BELCH!) -- just as well -- last month of university right now and I "should" be busy with papers and such -- My panels will be a downscale version of what you did -- mine will be soda cans and cardboard.
dumptruck: interesting build(s). While I'm still stockpiling aluminum cans for a future build (BELCH!) -- just as well -- last month of university right now and I "should" be busy with papers and such -- My panels will be a downscale version of what you did -- mine will be soda cans and cardboard.
While I've yet to assemble a speaker box with it yet I am still building my "composite" material (soda cans between two layers of cardboard.) Early tests of one panel show that while a single layer of cans will support me (210+ Lb.), the knock or hit test shows a resonance, a sort of "boing", not surprising considering the materials.
Meanwhile, I've found another "free" material that might work as well as foam board for speakers: coroplast. I haven't priced it, but I've collected a few "illegal" road signs (advertising) and used one panel to make a DIY tablet protector case. For the record, Gorilla glue holds to it very well. Super glue, pretty good too. Coroplast would make an interesting part of a sandwich, or even two layers with the "lines" at 90 degrees angled. Where is Bateman when we need him 🙂
Meanwhile, I've found another "free" material that might work as well as foam board for speakers: coroplast. I haven't priced it, but I've collected a few "illegal" road signs (advertising) and used one panel to make a DIY tablet protector case. For the record, Gorilla glue holds to it very well. Super glue, pretty good too. Coroplast would make an interesting part of a sandwich, or even two layers with the "lines" at 90 degrees angled. Where is Bateman when we need him 🙂
Have used coroplast to mock up baffles. Also use it for rc planes. Both adhesives work well, but SG isn't as messy and can be cured instantly with pacer tech. zip kicker.
Wouldnt use it in a finished project, too flexible.
Wouldnt use it in a finished project, too flexible.
I was on my Honeymoon 😀
As for coroplast, a couple of ideas:
1) check out recumbents.com. They use coroplast to make fairings for streamliner bikes. There's one dude in particular who's written at least a dozen articles on how to work with it.
2) The company that makes coroplast just introduced a honeycomb coroplast that looks like a cool alternative to Nomex honeycomb
SG = Scotch Guard? That's a locked liquor cabinet right 
Welcome back Bate-man! Metropolis needs you 🙂
Yes, Coroplast has a HPV on their site.
Aw, crap, I even got beat to the Tablet holder idea: Here's a link on Coroplast* site:
Coroplast | Innovative Uses
Admittedly mine looks much less elegant, but is a DIY made-to-order case, basically just 3 pieces of plastic partly covered on the outside with some teal-green leather I had from an old project. Other than some Velco closures, no incremental cost and a type of recycling if you allow that definition for removing illegally placed advertising signs** 🙂
* Not to be confused with chloroplast, which is a natural product billions of years old and mainly of use if you are a photosynthesizing organism 🙂
** from reading Florida law, as far as I can tell, most are fair game with in 15 feet of the "right of way", certainly that means 15' of the road. There are exceptions, such as advertising sale of the property. More's the pity, because there are such large signs on a field next door to my 'hood. On the other hand, illicit sign touting some church easily removed by a heathen such as myself
Welcome back Bate-man! Metropolis needs you 🙂
Yes, Coroplast has a HPV on their site.
Aw, crap, I even got beat to the Tablet holder idea: Here's a link on Coroplast* site:
Coroplast | Innovative Uses
Admittedly mine looks much less elegant, but is a DIY made-to-order case, basically just 3 pieces of plastic partly covered on the outside with some teal-green leather I had from an old project. Other than some Velco closures, no incremental cost and a type of recycling if you allow that definition for removing illegally placed advertising signs** 🙂
* Not to be confused with chloroplast, which is a natural product billions of years old and mainly of use if you are a photosynthesizing organism 🙂
** from reading Florida law, as far as I can tell, most are fair game with in 15 feet of the "right of way", certainly that means 15' of the road. There are exceptions, such as advertising sale of the property. More's the pity, because there are such large signs on a field next door to my 'hood. On the other hand, illicit sign touting some church easily removed by a heathen such as myself
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I just realize there're venders providing core-only paper honeycomb -- without top/bottom surfaces.
Are you thinking what I'm thinking? 😀
Are you thinking what I'm thinking? 😀
Would that be to make curved panels? I still have not given up my dream of making a sub from alternative materials, despite the not-quite-fact that in the amount of time I have already wasted on that fool's errand not to mention the cash, I could have bought a truck load of marine plywood, a large wood shop and hired elves to work in it, copied Danley's best designs and be sued by him, flee the USA and set up an illicit tapped horn factory in mainland China.
I am still convinced there must be a means to make a huge sub enclosure out of coat hangers (frame) old newspapers (panels), perhaps with a few coats of shellac to make them stiffer 🙄
Here be (bee?) the link to the Coroplast honeycomb product. Curious: this is not mentioned on the main Coroplast web site!
Well on second look yes it is, but the point is I just found it and I am so elated 🙂
Stinger Honeycomb Board
I am still convinced there must be a means to make a huge sub enclosure out of coat hangers (frame) old newspapers (panels), perhaps with a few coats of shellac to make them stiffer 🙄
Here be (bee?) the link to the Coroplast honeycomb product. Curious: this is not mentioned on the main Coroplast web site!
Well on second look yes it is, but the point is I just found it and I am so elated 🙂
Stinger Honeycomb Board
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What I said is about the core-only honey comb material. (not ready-made whole board)
When it's only core, it's easily bent, so, first you can lay a peice of paper (or other thin/soft material) into a curve, then glue on the core, and then lay the top surface. Also, this procedure can be repeated to obtain a very thick mult-layer comb.
The possibilities are infinite. 😀
When it's only core, it's easily bent, so, first you can lay a peice of paper (or other thin/soft material) into a curve, then glue on the core, and then lay the top surface. Also, this procedure can be repeated to obtain a very thick mult-layer comb.
The possibilities are infinite. 😀
OK, now I understand. Does Coroplast offer just the honeycomb without the facings? I did not see that, but to be fair, I did not see the Sting product at all the first time I perused the web site. I think its link is on the home page, but if you click "products" no mention of Stinger board. Fire that web designer 🙂
Please share what, if any, curved projects you come up with. Hopefully it won't be a failure like other ones mentioned here at diyaudio.
Please share what, if any, curved projects you come up with. Hopefully it won't be a failure like other ones mentioned here at diyaudio.
I heard a system made from cardboard honeycomb composite. It had a relatively thick face on each side, around 3/16" thick and the honeycomb was 1" or so. This stuff was made for dance floors and it was stiff and light. The system sounded fine. Another system was made from a sandwich of hardboard and styrofoam. That one also sounded fine.
I saw it on the local auction web: ÅS¤Ñ©ç½æ-·j´M5400¸U¥ó°Ó«~
So I thought it's possible in other places, too. It's just a semi-finished material. I don't see why it can't be obtained.
So I thought it's possible in other places, too. It's just a semi-finished material. I don't see why it can't be obtained.
Ron: encouraging report for us experimenters!
CLS: yes I have seen just the honeycomb, but this may not be Coroplast brand.
CLS: yes I have seen just the honeycomb, but this may not be Coroplast brand.
Interesting thread!
I have a dodgy back and some sheets of honeycomb cardboard here. Hoping to replace my 30kg+(~70lbs) 12inch subs with something well under 10kg using 8inch drivers. Initial thoughts are using very thin ply laminated to the honeycomb cardboard.
The boxes will be around 12l each, so I'm thinking that the small size and low frequencies involved will mean that lack of damping won't be a problem(like in a sonotube sub) and the stiffness will be adequate.
Anyone care to comment on the likelihood of success?
I have a dodgy back and some sheets of honeycomb cardboard here. Hoping to replace my 30kg+(~70lbs) 12inch subs with something well under 10kg using 8inch drivers. Initial thoughts are using very thin ply laminated to the honeycomb cardboard.
The boxes will be around 12l each, so I'm thinking that the small size and low frequencies involved will mean that lack of damping won't be a problem(like in a sonotube sub) and the stiffness will be adequate.
Anyone care to comment on the likelihood of success?
Rather than work on my term paper why not bump this old thread? I've recently been reading here about a perhaps related idea and even from a legitimate source: the old BBC LS3 ?
[edit, duh, this thread: ]
http://www.diyaudio.com/forums/mult...tter-non-ls3-5a-speaker-based-t27s-b110s.html
speaker designs. Among other departures from then- (and today's) wisdom, they said to use thin cabinets (of wood, albeit, although perhaps coroplast might work?) with heavy damping from bitumen panels (coal tar?). Does it all come down to lossy cabinet? Lower the resonances?
[edit, duh, this thread: ]
http://www.diyaudio.com/forums/mult...tter-non-ls3-5a-speaker-based-t27s-b110s.html
speaker designs. Among other departures from then- (and today's) wisdom, they said to use thin cabinets (of wood, albeit, although perhaps coroplast might work?) with heavy damping from bitumen panels (coal tar?). Does it all come down to lossy cabinet? Lower the resonances?
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