Build advice for cab material

[pablyth]

Seriously considering building a J12 using Plyboo.

Plywood made from bamboo. [url="http://www.plyboo.nl/bic/5_info2.html"]http://www.plyboo.nl/bic/5_info2.html[/url]

Sounds strong and quite dense to me, have a feeling it'd make a good cab. Although I'd love to hear from anyone who disagrees?

[Mr. Foxen]

What you want in cab material is strong, stiff, non-resonant and light. That website doesn't actually give any details at all on it's actual properties, which indicates marketing and style over actual physical usefulness. I'd imagine it is quite a high proportion glue due to bamboo only coming in strips, so it probably disproportionately heavy, and bamboo is known for springiness rather than stiffness. I think a cab made out of it would bounce better than most. Flooring and furniture benefit from spring, I think traditional hardwood ply would be better for a cab, but you could do it just to be different, it wouldn't end up heavier than an MDF cab (which benefits from being very non resonant, and cheap, but loses out on the weight and strength). Oh., and when you are working it, it will have the most vicious splinters going.

[pablyth]

[quote name='Mr. Foxen' post='1003230' date='Oct 28 2010, 12:14 AM']What you want in cab material is strong, stiff, non-resonant and light. That website doesn't actually give any details at all on it's actual properties, which indicates marketing and style over actual physical usefulness. I'd imagine it is quite a high proportion glue due to bamboo only coming in strips, so it probably disproportionately heavy, and bamboo is known for springiness rather than stiffness. I think a cab made out of it would bounce better than most. Flooring and furniture benefit from spring, I think traditional hardwood ply would be better for a cab, but you could do it just to be different, it wouldn't end up heavier than an MDF cab (which benefits from being very non resonant, and cheap, but loses out on the weight and strength). Oh., and when you are working it, it will have the most vicious splinters going.[/quote]

Thank you for your reply and advice, it has prompted me to delve a little deeper.

I totally agree with your weight and difficulty of working comments, the weight alone could well be a reason to forget this whole thing. It's about 20% heavier for plyboo over plywood, hmmm don't know if I can accept that.. Bamboo is seriously stiff in one direction though, and with opposite directions working in the ply I'd imagine it should have a good overall stiffness.

After finding a set of $18k speakers made from bamboo I searched more, as this seemed to indicate bamboo is good for audio. (or they are just trying to show off with alternative materials)

[url="http://www.ascendacoustics.com/pages/products/speakers/SRM1/srm1.html"]http://www.ascendacoustics.com/pages/produ.../SRM1/srm1.html[/url] - Bamboo speakers seem to be fairly high price range items.

Now I'm just confused though - [url="http://library.witpress.com/pages/PaperInfo.asp?PaperID=18"]http://library.witpress.com/pages/PaperInfo.asp?PaperID=18[/url] - This is related to fibres, but absorbing sound? Guess I'm doing lots more research. I'll save that for at work, if I don't forget it totally over the weight.

Edited October 28, 2010 by pablyth

[Mr. Foxen]

Sound absorbing is all about converting the air movement energy into other energy, usually via friction producing heat, so the bamboo fiber absorbing sound is because the fibers are free to rub together. Doesn't apply when they are glued.

Bear in mind weight and durability issues aren't there for monitors, because you aren't expecting to be moving them much.

I'm pretty sure it will be equivalent to very high quality ply in most ways, as with most things, the existence of cheap poor quality ply drags down it's reputation overall. Really, to achieve stiffness, you can do it with cunning construction, tensioning and bracing, have a look at aircraft woodwork to see how to achieve maximum stiffness for minimum weight.

[pablyth]

[quote name='Mr. Foxen' post='1003269' date='Oct 28 2010, 02:17 AM']Sound absorbing is all about converting the air movement energy into other energy, usually via friction producing heat, so the bamboo fiber absorbing sound is because the fibers are free to rub together. Doesn't apply when they are glued.

Bear in mind weight and durability issues aren't there for monitors, because you aren't expecting to be moving them much.

I'm pretty sure it will be equivalent to very high quality ply in most ways, as with most things, the existence of cheap poor quality ply drags down it's reputation overall. Really, to achieve stiffness, you can do it with cunning construction, tensioning and bracing, have a look at aircraft woodwork to see how to achieve maximum stiffness for minimum weight.[/quote]

Thank you for your explanation, makes perfect sense.

I agree and think it's not practical for anything other than stationary speakers, but I've enjoyed the hunt anyway. I will be building a cab from plyboo, but it will be a stationary use sub. Mostly just for the sake of it!

Thank you for your comments, it's appreciated.