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Acura RSX Fiberglass Subwoofer Fabrication

Tools Required

  • table saw
  • jig saw
  • drill
  • rotozip

Supplies Needed

  • fiberglass resin w/ hardener (I used almost a gallon for mine)
  • fiberglass matting/woven cloth (I used both, the fb glass cloth is a lot easier to use)
  • blue painters tape (you can use the reg. tan stuff but its harder to remove from glass)
  • disposable paint brushes (several)
  • aluminum foil
  • MDF 3/4" plywood
  • Liquid nails
  • screws
  • protective gas mask


For those of you who considered building a FSB but needed more guidance, this is my offering. I think I should mention right off that I'm not building a competition system. My intentions here were to build a single 10" sealed box for a more balanced sound (audiophile wanna be and to save trunk space (golf clubs). Hopefully the experiences I share will help anybody no matter what your intentions are.

I did a lotta research before I got started and I give a lot of credit to Club RSX.com Forum/website.

After I decided what size sub and what kind of enclosure I wanted to put in, I needed to figure the volume of the enclosure. Well this is a bit tricky if the shape of the box is contouring around wheel wells and the like. So here's the trick. I got a cardboard box the recommended size for the sub and filled it with styro foam popcorn. I placed the styro in a large garbage bag and conformed it to the spot in the trunk where the sub was to be. I eyeballed it and used masking tape to outline the border of the box. There is some tolerance in size & I'm no calculus buff so there it is.

I'm a pretty handy guy around the house and did carpentry for a few years so I employed the golden rule "MEASURE TWICE ,CUT ONCE". You can rush through something like this and have a disaster but you can never take too much time to do it right. So for the newbie: Take your time grasshopper, and the prize shall be yours.

Step One

I taped off the area really well. I was paranoid as hell that I would destroy the trunk of my new RSX so I went over board!! Remember, its easier to spend a little extra chump change than to replace the panels and carpet in the trunk!!

Step Two

This is at least a couple of layers. Note that I'm going over the trunk liner.

It's a personal call, what can I say. The box will be easy to remove and I can keep the trunk clean.

Step Three

I then used cut pieces of foil to go over the tape. Why foil? Not really sure it's what I've seen other people use it and it may be easier to peel the form out later, just a guess. I used double stick tape to fix them in place, taped the seams between. You'll see in the next pic that I started the rows of foil at the bottom overlapping the next coarse of foils over the previous as if I were laying shingles. The point here was to avoid any seepage - again protect your investment,overkill or spill!

Step Three - Additional Image

The below pic shows the finished tape and foil layers.

Step Four

I draped plastic drop cloth over everything b/c the fbg resin is nasty stuff, very drippy and sticky. I took every precaution I could. I did the taping and foiling the day before the resin. You really want to do this on the weekend when you don't have to be any where real soon. You can't go driving around while the stuff sets up. The mix of hardener and resin I used in the first batch was conservative and took a while to set. After the first coat dries you can pop it out and do everything else outside the car.

Step Five

The pic shows the first layer of resin. You start by painting the resin on the tape layer immediately following with fiberglass material and then another layer of the resin. A note about the resin and hardener: definitely read the instructions about this. The more hardener you use the faster it sets and begins to the less you use the longer it will take. It takes a long damn time to set if you don't put enough in. There is a little trial and error involved. The colder it is the longer it takes to set up as well. I had never done this before so it was a little hit and miss. Another tip is that it seemed to work better to make stabs with the brush. Air bubbles are bad, you want to avoid them b/c they weaken the strength of the box.

Step Six

The hardened form and I'm about ready to pop her out. If you can do the work outdoors in reasonable temps the better. The fumes were pretty heinous in the garage. A gas mask is a must, the stuff will make you stupid if you breathe it in. I got my mask from Home Depot for about 27 bucks. You shouldn't be able to smell the fumes at all with the mask on. I did the following 4 layers outside the car. After the basic form is done the other layers go really quick.

Step Seven

The next pic shows the form dried and in its future home. Still a little work to do yet. I trimmed the form to get the crappy edges off with a rotozip.

Step Eight

I forgot to take a few pics during the fabrication of the MDF facing- sorry. Hopefully the next couple of pics will kinda show what I did.

Step Nine

I used a jig saw to cut the hole, a table saw to get all the angle cuts flush where the pieces of MDF are joined. I also used liquid nails between every piece of wood and ran a bead at the seams. I screwed the MF together with 2" screws pre-drilling and counter sinking the screws. MDF is just fancy particle board that will fall apart if you rough house it too much. I wanted the option to mount the amp just to the left of the hole for a cleaner look. As I'm writing this, I'm still undecided about the amp but still have all the options.

Step Ten

It's hard to see from this pic but there was quite a bit of jigsawing to get the side piece of MDF to fit the glass box. I measured quite a bit to make sure the dimensions were right before I screwed and glued this sucker together. You don't want to get done and it not fit. Here's another pic of the back.

Step Eleven

I used a hot glue gun to tack everything and just used painters tape to hold it together before I made it permanent. I used strips of fleece inside the box with just resin to join the MDF and the glass form. I'll show more pics down the page a bit. I followed that with glass and resin on the outside seams. My plan is to use industrial Velcro tape to affix the box to the trunk carpet.

Note: you can fool the sub into thinking the box is a little larger by filling the space inside with R-19 or pillow stuffing. Supposedly you can fake an increase of size by 10-13% b/c the sound will bounce off the material before it gets to the back of the box. I think it's around 1 pound of stuffing per cubic foot. Don't stuff it in there real tight either, keep it fluffy.

Here's a pic of the fleece material slathered in place with just the resin.

I tacked the fleece in place with a hot glue gun and glopped a bunch of resin on it. The object here is to make it airtight. I bought the fabric at walmart for about 4 bucks. Fleece seems to work best, it really soaks up the resin. After its dry it will be hard as rock.

Step Twelve

When I get the carpet on it should look fairly well integrated into the trunk space.

Step Thirteen

A dry run with the amp and speaker

Step Fourteen

With carpet and sub loaded

Step Fifteen