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Discussion Starter #1
I am trying to fabricate a fiberglass speaker box similar to this


These are my rough sketches so far




i have some experience with sound systems and fiberglass. I have never worked with woven fiberglass matting. I am curious to how many layers i should have to make the box rigid. I have been told i should not lay more than 3 or 4 layer without letting the those 3 to 4 layers cure completely.

I am planning on laying a piece of MDF wood shaped to the spare tire well on the support brace to make a flat surface to lay fiberglass on. I do not want to remove the support bar in the spare tire well that the spare tire bolts to for fear of losing some frame rigidity. I also do not want to remove the brace that holds the spare tire closest to the back of the car in the spare tire well so i can get a level surface to lay the MDF wood on .

I am planning on using MDF wood to make the top of the box/raised trunk floor. I am going to have the MDF wood cut into 3 sections. 2 side pieces to make the trunk floor level. One piece to be the top of the speaker box. I am going to have 1/2" wood posts holding the corners of the Top box to the bottom approximately 11" inches apart from the bottom MDF wood in the spare tire well.

I then plan on wrapping Lycra or some similar material over the top MDF wood piece and over the 1/2" wood post and over the bottom MDF wood piece. I will do this in 2 separate stages. Once doing the top section. Once that is cured with however many layers are needed. I will then finish matting it on the bottom.

I plan on cutting the fiberglass matting into roughly 5" to 6" squares

Similar to this


I am planning on having one 12" Alpine type X

I am told i should trim out the hole for the speaker after the first few layers cure.

I might have left out some steps and been vague on others.

I was told to take a cold shower afterwards to help get the fiberglass of the skin because the hot shower will close your pours.

I have an endless supply of tools, extraordinary discounts and extra hands thanks to collinsville area vocational department.

My questions are as follows:
How many layers do you suggest using? I was told to have anywhere from 5 to 8 layers. I was also told to go by the rule of thumb. That is if you can flex it with your thumb you need more layers.
Which ounce fiberglass to use either 1.0 or 1.5?
I was told for my final layer to use tightly woven fiberglass matting to give it extra rigidity, Is this correct?

I cant think of any other questions off the top of my head but any advice or comments will be greatly appreciated.
 

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7 layers of the hair fiberglass mat, 1 layer of woven mat (easier to finish) make sur eyou get the 7 lays pretty smooth or the last layer wont lay right.
 

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Discussion Starter #4
thanks! i did some math and figured i would have about 5.5 cuft of air space in the box. Is that to much for a type x? I read that they only need around 1 cuft to 2 cuft. Will i be getting in to the danger range of to much air space and chance blowing the speaker?
 

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I fiberglassed my sub in, although I have to admit I don't have any answers to your questions, that was too long ago. I just bought a bunch of the stuff and kept adding layers until it seemed strong enough. I also didn't fiberglass everythign but instead used a fair amount of MDF. The bottom of the enclosure is all fiberglass, but the front, sides, and top are MDF. I reached in through the sub holes to seal the inner edges.

I did a 2 layer top, the lower layer had holes just right for the subs and the screw holes for mounting. The upper layer I cut about 2" diameter bigger to help the subs look more flush. The grilles still stick up but not very much. It's a personal preference I guess.

On top of all that is a 3rd, thin piece of wood that was covered in carpeting. It's easy to lift up and out of the way and with the carpet I'm not very concerned about scratches or anything if & when I do use the trunk for groceries or something. I've scratched the grilles a few times but touch-up paint fixes that.

I put my amp on a board up in front of the sub box, and carpeted it also.

I don't know how much air space those subs need but I would make sure that you get as close to that as possible. If you like your design, then consider a different sub. Or if you like the sub, consider shrinking your design or even possibly adding 2 subs. Do try to get them matched though (the sub to the box volume), definitely.

I've got some pics here: Index of /greg/eclipse/stereo I did this about 6 years ago, and a lot of small things have changed since then (different grilles, I painted the amps, etc.) but maybe you'll get some ideas.
 

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you must have a very shallow speaker because i have the same setup with an L7 but i had to flip mine. I made mine out of MDF and just started to glass it. i guess what i'm sayin is that if your runnin it flat across double check you will have enough room due to the spare tire mount.
 

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Yes 5.5 cubes is way more then you need for a X, is it a 10" or 12" I have 2x12" X's in about that much space and box was too big for trunk so temp in my back seat till I build another,

How high is it comming to the top liner our hatch closes pretty close to it you wanna make sure you have clearence.

It's sealed right?
 

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Discussion Starter #8
i plan on it being sealed. Will it still be to big after taking into account the size of the sub. after the size of the sub in the box i should have about 2-2.5 cuft of space. i am planning on having 1 12inch type x. It will be sitting 11inches high off of the support in the center of the spare tire well. I am removing the spare tire.
 

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i plan on it being sealed. Will it still be to big after taking into account the size of the sub. after the size of the sub in the box i should have about 2-2.5 cuft of space. i am planning on having 1 12inch type x. It will be sitting 11inches high off of the support in the center of the spare tire well. I am removing the spare tire.
ever thought of making it out of wood? I made a few boxes similar and wood is just as easy and lot less work...Just a thought. Good luck! look forward to pics
 

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Discussion Starter #10
ya i thought about doing it in wood but then i figured this would be a great time to practice fiberglassing. I have all the resources i could want. So i figured why not mess around with it. And woods just plain and boring... i want a challenge!!! im gonna start working on it hopefully next week. This weather has been horrible. I gotta finish shaving a Tiburon and taking the dents out and repainting it but hopefully i will have that all wrapped up Friday and can start fresh on monday with my eclipse
 

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ya i thought about doing it in wood but then i figured this would be a great time to practice fiberglassing. I have all the resources i could want. So i figured why not mess around with it. And woods just plain and boring... i want a challenge!!! im gonna start working on it hopefully next week. This weather has been horrible. I gotta finish shaving a Tiburon and taking the dents out and repainting it but hopefully i will have that all wrapped up Friday and can start fresh on monday with my eclipse
 
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