Carbon speaker cabinet?

[djjustice]

I know of a company that uses a carbon fiber cabinet along with their diamond tweeter and 3'' midrange. They charge over $150,000 a pair for them, and talk about how exotic the carbon fiber is, as if its VERY expensive. The last time I checked you could get a 3'X3' roll of CF for around $65. With how rigid it is, and along with the fact that it could be vacuum formed, do you think it could be the new higher end speaker DIY material? I do not think it would add any odd resonances, and would require little padding. Also, if you wanted to, you could make a B&W like speaker, utilizing a sphere than evens out towards the back in order to stop baffle resonances, a other affect caused by the standard front baffle. DON'T CRITICIZE ME AND CALL ME AN IDIOT, its just an idea.

[Max_Andrews]

Well you could do it, but it wouldnt be cheap. Take make it strong enough to perform as well as 3/4" MDF, you'd need maybe eight to ten layers, probably costing around $1000 for a pair of medium sized cabinets. Also to take into account is that obviously you'd want the carbon to be visible for the cool factor, so you'd need to learn how to do cosmetic layups which is not easy at all. What's the point in spending a grand if you're going to paint it to look like MDF anyways?

Another option for odd forms would be to use fiberglass, which they do use for high end car subwoofer cabinets quite frequently. The only difference between carbon fiber and fiberglass is that for the same strength you need about 2.5 times more fiberglass, which makes it a lot heaver, but we're not building a ferrari we're building a speaker, so the cost savings would be a lot better here compared to carbon fiber.

[billfitzmaurice]

Carbon fiber is a wonderful material for speakers, but as long as Boeing and the rest of the aerospace industry are using it up faster than it can be churned out the price will remain prohibitive.

[Max_Andrews]

Here's a quick rndown of how to make a fiberglass box from scratch: <A HREF="http://www.garbled.net/tim/fiberglass.html">http://www.garbled.net/tim/fiberglass.html</A>

[djjustice]

I need to buy a sheet to experiment with, and see exactly how strong it is. Whenever I sneak into a car display area, for ultra high end cars, I try to find the carbon fiber and test the strength. I managed to observe the carbon on a Carera GT one time, and it seemed very stiff, even though it might have only have been double the width of the rolls you can buy. The only thing is the you might have to separately make each side, then put them together; vacuum forging would likely leave a seem somewhere undesirable, unless theres a different technique than the one that I know of.

[Max_Andrews]

I'd recommend <A HREF="http://www.cstsales.com">http://www.cstsales.com</A>
they have good prices, a good selection, and they let you buy in single yards or largeer quanities for a discount. I've ordered a few times from them and it's always gone well.

As for the forming, the best way would be to make the shape you want out of styrofoam using a hot knife and then just lay the carbon up on top of it. You can probably find a hollow styrofoam shape the right size by looking through packing styrofoam in the back of stores and such (like the two-piece styrofoam clamshells that laptops and stuff some boxed in).
making the sides separately kind of ruins the point of using carbon fiber, because then you'd need a strong internal frame to hold it all together.

[mikec]

Make it out of fiberglass, then use cargon as the top layer for looks?

________
ZOLOFT CLASS ACTION

[Max_Andrews]

That's a good idea, I think cosmetic carbon may be a bit cheaper (just a bit) as it's not as dense as the stronger structural carbon. So if a 50" wide yard is about 30 bucks, you could get the look of carbon for about i sheet per speaker depending of course on the size of your project...

[billfitzmaurice]

> Make it out of fiberglass, then use cargon
> as the top layer for looks?
Fiberglas is too flexible. The advantage to carbon is stiffness. If I was going to use a carbon exterior it would be over a honeycomb matrix. See: F-117.

[Max_Andrews]

Using anomex honeycomb sandwiched between two carbon layers might be a good strategy. Cheap nomex is hard to find though, it's what they use in airplane and helicopter wings

[Steve Henry]

> I'd recommend <A HREF="http://www.cstsales.com">http://www.cstsales.com</A> they
> have good prices, a good selection, and they
> let you buy in single yards or largeer
> quanities for a discount. I've ordered a few
> times from them and it's always gone well.

> As for the forming, the best way would be to
> make the shape you want out of styrofoam
> using a hot knife and then just lay the
> carbon up on top of it. You can probably
> find a hollow styrofoam shape the right size
> by looking through packing styrofoam in the
> back of stores and such (like the two-piece
> styrofoam clamshells that laptops and stuff
> some boxed in).
> making the sides separately kind of ruins
> the point of using carbon fiber, because
> then you'd need a strong internal frame to
> hold it all together.

Another option I learned from my car audio days is to build an MDF skeleton out of 1 X 1 strips in whatever shape you need. Use MDF rings for driver mounting. Then wrap the skeleton in fleece (sweats material) from the fabric store (cheap), using a staple gun. The fleece is much thicker than several layers of mat. Then brush resin onto the fleece. The first coat soaks into the fleece, creating a hard shell. Then uses as many coats as necessary to pass the knuckle test (usually 2 - 3 more). Rough sand to find any low spots, bondo, then primer & sand to achieve your desired surface. Then paint it or better yet, take it to your buddy at the body shop & have the only Ferrari red speakers in your town.

[nate]

It's a good idea! I've built dozens of spherical loudspeakers with carbon fiber and fiberglass. I even took one of them to HE 2003 with Ray Kimber.

<A HREF="http://www.enjoythemusic.com/hifi2003/boylan/friday/">http://www.enjoythemusic.com/hifi2003/boylan/friday/</A>

It takes some time to get used to the material. You need a nice respirator tyvek suit and lots of gloves. Also, carbon fiber is more picky when it comes to the type of resin used as it doesn't "wet out" as easy as fiberglass. A good alternative to carbon fiber, (which is very $$$ due to the war) is 10oz fiberglass.

[djjustice]

Those speakers were your? Nice job.