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http://www.cardomain.com/member_pages/view...d=337907&page=2




I installed a 12" subwoofer in the spare tire well today. I'm still waiting for some expanding foam insulation to dry before I can trim it down. While I wait...

Take a look at the first picture. A 12" subwoofer is the largest that will fit, and even then mounting depth may be a problem. I installed the subwoofer on the top end of the trunk, as a center mount is impossible due to a bulge in the well. That bulge, however, is extremely important- the screw used to keep the spare tire in place is also used to keep my subwoofer in place. In the rear of the car, the well has many, many curves, but I did my best to create a piece of wood that outlined the rear of the car and I mounted that to my main baffel. I'm sure it isn't air tight, but the rear should act somewhat like a speaker port.

My baffel was 28 1/2 inches wide and a little over 28 inches long. I cut the sides and front at a 15 degree angle to coincide with the slope of the well (which is more like 30 degrees, but I wanted space for my foam). Since this baffel will bear weight when the trunk is full, cutting an 11" hole for my 12" subwoofer was not an option. Instead, I cut a design, with the largest hole being 2" in diameter in the center. It's a poor design, and isn't what I had originally planned. Nonetheless, it lets an adequate amount of air through and still will bear lots of weight above.

Since I mounted the subwoofer directly against the bottom of the baffel, the woofer surround laid up against the wood. This completely prohibits woofer cone movement, so I used a router to bore out room for the cone to move. I bore out 2 layers of the 5-ply, 3/4" wood, about 3/8". I calculated this to give me nearly half an inch of woofer excursion, which is more than the Xmax of my relatively inexpensive Infinity subwoofer.

Once the woofer, baffel, and back was assembled and glued, I put it in place and ran this expanding foam all around the edges. I really used a lot to ensure no rattles. The foam dries hard and can be sanded and cut. I will need to cut it once it dries to get a nice smooth, continues surface, and I can furthermore cut it again if I ever need to remove the subwoofer (and repair/replace it). Not an elegent solution, but my best one.

The sound is fantastic- much better than my box. The gain is incredible since the back of the enclosure is the car- steel, not plastic. Not only is their massive gains from this, but despite the gains it does not sound boomy. The steel enclosure is rigid enough to give me nice, clean bass that fills the cabin.

All in all, I'm pretty pleased.

Update: I shaved the excess foam and put the carpet trunk liner back down. Folding the rear seats back up into place still takes a lot of the sound away, I hate that. The subwoofer sounds pretty good. Unfortunately, I can localize the bass sounds from the rear- the sound doesn't blend in with the front speakers as well. It may be a phase issue, but I doubt it- I think it's simply due to the upper bass being brought out more with this enclosure. I put some dynamat on my license plate, but there are a few minor rattles underneath the car at higher volumes.

On an unrelated (yet related note); I just ordered some resisters so I can redo my crossover network for the front components. It should help with localizing the sound up front by balancing the sound, and in doing so make the harshness of the stock head unit less prominent (and I hope undetectable).

And, in case you forgot what my car looks like... :D
 

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Reading Topic: Pictures of my new stealth spare tire subwoofer box

I wonder if it's possible to make the rear seats more acoustically transparent. I've looked, and they currently have a steel sheet-metal back to them. I considered trying to cut holes in the steel, making them look like swiss cheese rather than a solid sheet, but this was only an idea.
 

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Reading Topic: Pictures of my new stealth spare tire subwoofer box

Thath last thing about cutting holes in the metal sounds like a good way to undermine the structual integrity of the seat. Crash hard enough and any hard cargo could bend the locking mechanism and make things fly into the car... At worst :)

I long to see how you will cut away that exess wood without damaging the speaker :) Or you maybe have cutting skillz :p Or is it supposed to be there?
 

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Reading Topic: Pictures of my new stealth spare tire subwoofer box

It has to be there- it bears the weight of cargo. That's exactly why creating the baffel was a challenge, and I had to route out the shape of the woofer surround on the internal side of the baffel.
 
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