I had a decent stock of coroplast panels, and a lot of foamcore, so I set about designing a sub enclosure. So far, I've got a coroplast outer skin, joined as a regular rectangular box with hot melt glue. All joints are caulked with loctite 2 in 1 adhesive caulk. Inside this outer shell, I'm in the process of laminating sheets of foamcore to the inner surfaces with the same caulk as constrained layer damping. Inside that, I'm working on a foamcore based bracing scheme a la B&W matrix. The top panel will be set in place, with a PPSL style dual 12" manifold upfiring, and simply held in place by weight. The combination of force cancellation, gravity, and a very light, stiff, and well damped enclosure ought to be really cool- and because I can disassemble it (the top panel with drivers mounted shall be wood and the only reasonably heavy part) it will be quite the fun toy to bring to DIY meets, where surprisingly often there are only piddly little sub yappers to deal with. Enclosed volume? Well.... it's designed to allow me to tune it really low.... 10 cubic feet or so after bracing and manifold displacement (the drivers would want 3-3.5 ft for sealed each). We shall see how it comes out!
Only minus I see is the main box cannot be disassembled. On the up side it can serve as an ice chest if your bracing allows.
Well, not surprisingly, the slow curing caulk, that is constrained between panels, is taking its sweet time, with the overall somewhat flexible assembly (bracing not yet installed) giving me a dilly of a pickle. I'm hoping that I can avoid having to scrap this one- I think I may yet pull it off, but may just wind up taking the longest route to cleaning out scrap materials in my garage, ever. There's some separation happening at the edges, etc- I have to believe that once I am done with layering panels inside, I can lock things back down somewhat.
And in a stroke of brilliance, I realized that I could make the panel flex work for me. The intent had always been to pressure fit the bracing scheme so as to pre-tension the panels (a dual sub assembly this lightweight needs all the help it can get!), and so, to clamp the panels down while what I expect will be a week before they TRULY cure, I inserted my bracing which I'd built outside the box (if I had it to do over, I'd just add a ton of strip bracing to the finished assembly) and viola, there's enough bulging of the coroplast panels that there's pressure across the whole surface of the internal foamcore walls.
Composites and lightweight materials:Mårten Design Coltrane loudspeaker | Stereophile.com
Seems it can be mastered...
Seems it can be mastered...
More lumber-free ideas...
A slight variation on the idea, perhaps. I googled "varnishing cardboard" today and it gets a lot of hits including this one, for a man who designs furniture of of cardboard.
Object Guerilla: Bent Cardboard
What is a speaker, if not a piece of furniture that makes noise? Your chair seat thirty seconds after the women have left the room does not count. 🙂
My interest was just in making a set of copier paper boxes more durable (by sealing them with polyurethane sealer). The particular boxes in question were painted by me a few years ago with leftover paints when I did loud colors in one bedroom. I don't expect them to support my 200 lb posterior, but it may keep them usable longer.
I seem to be somewhat more rational than a year ago (when I built a huge subwoofer from hollow core doors) which failed, just as everyone here said it would. Cardboard would be a likely covering ("skin"?) for my Marimba I line-array-quarter-wave-whatever that I rather like. Unless xrk971 shows up with a free supply of foamcore...
A slight variation on the idea, perhaps. I googled "varnishing cardboard" today and it gets a lot of hits including this one, for a man who designs furniture of of cardboard.
Object Guerilla: Bent Cardboard
What is a speaker, if not a piece of furniture that makes noise? Your chair seat thirty seconds after the women have left the room does not count. 🙂
My interest was just in making a set of copier paper boxes more durable (by sealing them with polyurethane sealer). The particular boxes in question were painted by me a few years ago with leftover paints when I did loud colors in one bedroom. I don't expect them to support my 200 lb posterior, but it may keep them usable longer.
I seem to be somewhat more rational than a year ago (when I built a huge subwoofer from hollow core doors) which failed, just as everyone here said it would. Cardboard would be a likely covering ("skin"?) for my Marimba I line-array-quarter-wave-whatever that I rather like. Unless xrk971 shows up with a free supply of foamcore...
[bump] subwoofer from trash lives again!
First, did anyone else ever do further experimentation? Recently I built my first pair of sort-of-Unity or Synergy waveguides completely out of coroplast signs. Part of my "design" goal there and in the accompanying subwoofer was to see if I could get passable, not to say optimum, results not only with cheap/lightweight material, but also with minimal cutting. This means I sized each waveguide to be made with existing panel sizes, mostly 18x24 inches in my case. Since they only go down to around 200 Hz, I said, why not a sub to accompany? A few hours' of effort (and no cost save sign-pilfering and glue) and now I have a 12" car sub on top of a coroplast box 24" high and 18" square width & depth. It is braced with a combination of triangle shaped coroplast "tubes" as well as scraps of lumber, and glue blocks for 90 degree edges.
Is it lightweight? Very. Is it perfect? No. There is the occasional buzz on music and certainly swept sine. I am going to brace it some more internally and also try some CLD (on outside, ease of access). Nothing heavy since light weight is a goal.
First, did anyone else ever do further experimentation? Recently I built my first pair of sort-of-Unity or Synergy waveguides completely out of coroplast signs. Part of my "design" goal there and in the accompanying subwoofer was to see if I could get passable, not to say optimum, results not only with cheap/lightweight material, but also with minimal cutting. This means I sized each waveguide to be made with existing panel sizes, mostly 18x24 inches in my case. Since they only go down to around 200 Hz, I said, why not a sub to accompany? A few hours' of effort (and no cost save sign-pilfering and glue) and now I have a 12" car sub on top of a coroplast box 24" high and 18" square width & depth. It is braced with a combination of triangle shaped coroplast "tubes" as well as scraps of lumber, and glue blocks for 90 degree edges.
Is it lightweight? Very. Is it perfect? No. There is the occasional buzz on music and certainly swept sine. I am going to brace it some more internally and also try some CLD (on outside, ease of access). Nothing heavy since light weight is a goal.
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