Fiberglass enclosure

[Clienthes]

I thought I remembered reading on here awhile back someone posting about building an enclosure out of fiberglass, but I can't find it now. Anyway, I'm wondering how fiberglass would work as a material for building a speaker enclosure. Does it have suitable accoustic properties, or does it resonate, is it too light, etc.?

I'm curious about the topic because I'm considering a rather large project that requires me to get some experience building with fiberglass. I thought a good practice project might be to build some speakers, maybe one of the mission accomplished speakers, but with a fiberglass box. Would that work as long as that the dimensions stayed the same?

If not, I'll just save the fiberglass for a toaster cozy or a canoe...

Thanks for the help; I love this forum!

[joecarrow]

The benefit of fiberglass is that it could be made into curved walls with ease, and thus could be made very light and rigid. This would make a great subwoofer enclosure, but it's hard to say how it would handle the mid/bass frequencies. People certainly make fiberglass speaker enclosures, but mostly it's done for car audio where weight and unusual shapes are of high importance.

[mefistofelez]

Anyway, I'm wondering how fiberglass would work as a material for building a speaker enclosure. Does it have suitable accoustic properties, or does it resonate, is it too light, etc.?

I have been contemplating similar idea (http://www.diyaudio.com/forums/showt...1#post1200501),
but with an addition of a "kernel", sandwiched between two layers (outside and inside) of fiberglass. The "kernel" could be made of material providing additional properties to the one of fiberglass.

Unfortunately, nobody seems either interested in this idea or willing to give any advice in this respect.

M

[joecarrow]

Please understand, it's not an area that the majority or home audio DIYers have a lot of experience with. You might have more luck with a car audio or boat forum. I have the background that if I had a budget, some tools, and a workspace I could come up with a solution for you- but I lack all of these, so I'm stuck combing the internet as you are now.

Anybody else in here have some experience with fiberglass?

[JasonB]

I have done a few fiberglass enclosures for car audio use. The thing with fiberglass is that the more curves you have in your enclosure the stronger it will be for a given thickness. If you are building a simple rectangular box you would be much cheaper off using MDF, as well as saving yourself a ton of labour.

I think it has the potential to make some really cool enclosures if you want something with a lot of curves, the only thing I'm not sure about is how acoustically inert it would be. It might be a good idea to damp the inside with some sort of coating like North Creek used to reccomend for their enclosures, the recipie escapes me at the moment but I do have it here somewhere.

The other aplication I have considered it for is for the outer layers of a home made honeycomb material, still might try that one some day.

Jason

[sliceofhogan]

Not really on topic:
I didn't use fiberglass, but my father and i used to make epoxy lamps. This could also be used for speakers.
We used to make the molds from clay or plaster. Then the molds were covered with special liquid rubber, to create a very detailed (and ofcourse elastic mold).
The rubbermold was fit into an outside supporting mold and on the inside also a mold was placed. The size of the inside form defines the wall thickness.
We also used special toner/paint, that could colour the epoxy from transparent to solid colour, depending on the mix.
The only real work is making a precise and perfect mold, after that you can use the molds as often as you want, and as i remember, the epoxy wasn't very expensive.

[Gir]

I remember seeing a spherical speaker made with fiberglass and them saying that it was quite sturdy and pretty good acoustically. Wish I remembered the link : \

[ThomasW]

I have a ton of experience with fiberglass, and fail to see any real benefit to using it to enhance traditional 'box' construction given the cost and hassle of working with it.

As others have posted it's great for irregular or complex curved shapes.

Laying up a horn using a one sided mold is pretty straight forward. But 'sandwich' construction is very complex requiring a multiple stage build process and access to rather sophisticated equipment. That's fine for production work but a little unrealistic for a pair or two of speakers.

One needs to wear a fullblown respirator when working with 'glass', if not say "goodbye" to your brain cells.

[Clienthes]

Thanks!

Thanks for the replies. Like I said, my main motivation for experimenting with fiberglass is to get a little practice/experience working with it. So I'm not really concerned with any advatages it might have for building a typical box, but If I'm going to do it, I'd like to end up with a usable product, so I am interested in any disadvantages.

I like the sub enclosure idea, if its doable.

[mefistofelez]

But 'sandwich' construction is very complex requiring a multiple stage build process and access to rather sophisticated equipment. That's fine for production work but a little unrealistic for a pair or two of speakers.

Dear Thomas,

Although I do not want to turn the thread into manufacturing process discussion, I actually respectfully disagree. Of course, my disagreement may be based on your and my differences in understanding the terms "very complex", "sophisticated equipment", and the like. ;-)

Consequently, I have no difficulty manufacturing the core for the sandwich, which is of an irregular shape. Once the core is made it is trivial to apply fiberglass, with which, just like you, I have quite an experience.

What I do not understand, and this was my original inquiry, is what material to use for the core.

M

[Dennis H]

Foam is the most common core material. Look for one that's easy to carve and is compatible with the resin you want to use.

http://www.aircraftspruce.com/menus/cm/foam.html

[mefistofelez]

Dear Dennis,

thank you very much for your answer and specifically the link, which is extremely useful.

I understand that I must select the material so that I can carve it. However, that is not the issue; other properties of the material is. For example, should the core material be absorbent for sound, should it have certain density, should it have voids or be void less (open cell vs. closed cell foam), should it be rigid, etc.

M