DIY monitors from composite material??

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heffree

Active member
Joined
Aug 17, 2011
Messages
30
not exactly sure if this is the right place to post this but...

i've had a bit of interest in learning about composites lately so i've enrolled in a class at the local tech college where i live.
seeing as how i have access to completely free materials (carbon, fiberglass, kevlar) i figured i may want to experiment with using these materials in a few audio related projects.

i have noticed some companies using fiberglass or graphite carbon composite for things like acoustic guitars and acoustic drums, but not a whole lot about speaker enclosures.
does anybody here have any experience with such an enclosure? would it even be worth it (time-wise; cost is not an issue) to try making one?
 
i've heard a couple carbon fiber snares that i've liked
thats actually another thing i'm thinking about doing. i have a friend here that makes custom snare drums (respira collective. pretty cool stuff) so i might have her help me out with it a bit....

but yeah, hopefully the reason why enclosures arent that common isnt because its a stupid idea. ha
 
Community Light And Sound started by making some really excellent fiberglass (composite) speaker horns.

They went broke. (And came back, but not the same innovation.)

I can think of several "composites" used in speakers. Plastic foam skinned with metal foil has been tried more than once as speaker-cone.

Many small/cheap speaker (and a few very-nice) housings are "plastic" but loaded with so much filler (for damping AND for cheapness/economy) that they must be regarded as composities.

One of my long-ago projects was carving a woofer horn in green foam, then 'glassing it so the crowd didn't pick chunks out. That didn't go well. (The curves, but also a ventilation problem.... I'm not welcome in that building.)

Particle-board is a composite of chips and binder. The "paper" used in everyday speaker cones is certainly a composite, and more complicated than newsprint.

What do you hope to gain? The usual goal of "fiber" composites is to get great strength in specific directions with minimum thickness. Speaker cabinets do NOT need great strength. What they need is moderate strength with considerable thickness, to span width with low deflection (thickness buys stiffness much faster than fancy-material). What speakers also need is considerable damping to take the ring off the inevitable resonances.

True, it is often useful to wrap portable speakers in fiberglass to hold the joints together when being dropped off the truck.

> completely free materials

So what the heck. Wrap a corrugated cardboard box in and out with whatever cloth and goo you like. Whack a hole and put in a speaker.

Or to be cleverer: wrap a ballon to get a semi-spherical cabinet (no sharp edges, different diffraction). You may (I did) find it awkward to apply sheet-goods to 2-way curved surfaces.

Not a "stupid idea". But when fully explored (acoustics, cost, etc) it often comes out less-than-best.
 
thanks for the info! maybe i'll just stick with the snare idea... haha

anyone else have any input?
 
A few companies have tried to take advantage of composite materials to allow them producing rounded shapes that do not lend themselves to traditional wood construction.
Elipson in France made spheres in stucco. They gave a try at GRP and reverted to stucco, because that's what the purists wanted.
Genelec made a GRP enclosure for their model 1022, but now they have moved to injected metal.
JBL was a pioneer with their 4682 "line-array" (in 1978!); technically not a composite material, it is made out a thermoplastic. Unbreakable. Like the EV S12.
Clair brothers have experimented with GRP and gave up because of the lack of accuracy and the high cost of the process (everything is done by hand).
I designed GRP loudspeakers in the 1980's and came to the same conclusion. The only market where it had a definite advantage was ice-rinks.
 
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