How to Build a custom fiberglass subwoofer enclosure.
 

Well, we decided to build a custom enclosure for my car, after we did my friends.

SO I figured I would illustrate how we did it, as well as another method.

First thing, we used a piece of 12" sonotube cut at an angle and plugged in the bottom using some MDF to form the sealed part of the enclosure at the volume we wanted it. We added an MDF ring at the top to mount the subwoofer to.

I then mounted each tube to a piece of ply wood as the base. From there I used a combonation of carboard, duct tape, and spandex to form all of the curves I desired, then coated the whole thing with a coat of fiberglass resin, to give it a little stiffness, as you can see in these images.

Construction 1

Contruction 2

Contruction 3

At this point I had actually laid the first coat of glass, but you get the idea. I didn't take pictures through the entire process, but you get the idea from what I have here.

After this, is the painstaking process of adding at least 4 more layers of fiberglass, more in high stress areas. Much sanding goes on between layers, and actually laying the glass can be difficult, and take a bit of skill, as bubbles under the glass are your enemy. The cloth I used was actually scraps from my fathers boat building supplies, he purchased from System Three Epoxies. The resin (and cloth) can both be found also at Home Depot, and similar stores.

After the glass was sifficiently thick, we used bondo to finish everything out nice and smooth, and wrapped it in speakerbox cloth I purchased from www.crutchfield.com using 3M spray adhesive.

Finished Enclosure

Finished Enclosure

At this point, another route that can be taken is to have the box painted. We also considered laying one layer of glass on top of the bondo, then adding several coats of resin with pigment added to it.

I built a new wood floor into my trunk that the enclosure actually sits in. I also hinged it so that I can still access my spare tire and tools, albeit from the back.

Ultimatly, the amp(s) for the subs are going to go on the trunk lid roof (fiberglass mount built of course). With an amp sitting at an angle in front of the enclosure for the components I would like to add to my trunk. The amp will be housed in a metal frame, that hinges forward, to allow the enclosure to swing up and forward when I need the frame.

This is the method I used, and I believe we have found a better method to provide a mold to lay glass on, which is two part foam. Once hardened, it can be shaped reletivly easily to whatever shape is needed, provided a nice solid backing to lay the glass on. While we have yet to try this, my friend has some glass work to do on his car, and we are going to use this method. I will let you all know how it turns out.

And apparently my image tags failed to work... little help?

I pasted the links into another browser and I'm really impressed. That is some really nice work, looks completely professional. I built my own MDF box but its no comparrison to the fiberglass.

http://www.wastella.com/DSC00893.gif

Im still trying to fix the images, but i think I may just link the pictures for the moment.

By the way, if you live in my area, my friend and I keep talking about doing these as a small sideline, drop me a PM, if you are interested.

that is pretty cool, I am guessing 12 in woofers? what did you end up putting in them, what sort of volume does the tube hold?

im thinking of doing some fiberglass work but for something else. you said you can buy cloth and resin at home depot but do you know where to buy that foam you can shave and mold?

Well, for the first part, they are 10 inch woofers, Infinity Perfect VQ's. The volume I used for each woofer was .75 cu ft, which was one of many recomended volumes in the manuals for them. In the long run, they will be run by (probably) 2 infinity amps at 460 watts a piece.

For the second, I'm not entirly sure, except that I have seen it here: http://www.cardomain.com/item/FSHFIFOAM2Q

I have a feeling however, that a similar product can be found elsewhere, at a lower cost.

Also found here by the way:
http://www.shopmaninc.com/foam.html

Nice work for a first timer :)
A warning about trying to use foam/fiberglass resin - most resins will simply eat the foam away. You'll need a polyester resin to seal the foam before fiberglass work.

Suggestions:
Create a framework/skeleton for the basic structure and leave the back side open - then stretch/staple fleece (found at any fabric store) over the skeleton. Once stretched/stapled apply several layers of fiberglass resin to the fleece and let harden. Once the fleece is hard you can apply the fiberglass matt to the INSIDE (hence leave the back of the piece open) and be left with a much smoother surface to finish prep. For finish work you can start with SMALL ammounts of bondo over the fleece to fix the larger flaws. For the final finish you can use a sprayable high-build primer/filler. This is basically a thin/sprayable bondo that sprays very smooth and is MUCH easier to sand than bondo/fiberglass matt.

This site provides excellent tutorials and basic project examples:
http://web.njit.edu/~cas1383/proj/main/

Heres a couple of advanced tutorials:
http://www.jlaudio.com/tutorials/mera/MERA_2002.pdf
http://www.jlaudio.com/tutorials/mera/MERA_2003.pdf

Good luck with your project(s)!!

Cool man, thanks. There are several foams out there they are selling that say they will not melt when using for fiberglass, but thanks again for all the websites.

where did you get the sonotube and how much? my google search results suck lol

I got the sonotube at home depot, and I think a 5 or 6 foot section, 12 inch diameter cost me like... Oh 12 bucks or something.

Oh yeah, how much was the total for ur project?

Not to jack your thread but here are some other great installs for anyone wanting to learn more about fibergalssing.

Alpine RSX Showcar install

Alpine Civic Showcar install

Alpine Mini Showcar install

My whole project probably cost me around 300 dollars, plus the subs. I also had to purchase a few tools (nothing big, but it adds up when you figure in sandpaper, the stapler I bought, sanding block... etc.) Plus I'm terrible at bondo, which is how we finished everything out smooth, so I probably could have gotton away with a can less, were I good at it.

What kind of fleece are we talking about? Like polyester, polar fleece?