Sub Project
 

My idea here was to build a sub box using as much of the parts that I have on hand and would fit in the factory location and have ease of access to the components in that area. I have a 2001 X5, no nav, non DSP, no premium sound. This left a bit more room to work w/. The material used is ½” MDF. After looking into the right rear panel and checking some of the posts here at X5world, the box started to take on a form in my head. I wanted to use some of the area below the floor which is how the box went from being square to having the notch. This also will allow the box to rest on and against the lip just below the manual gas door release which was insulated with 3M pipe insulation and allows the need for only 2 screws to secure the box in place. The inside of the quarter panel was treated w/ CAE V-block to dampen noise and vibrations. The bracket that holds the gas door release had to be insulated as well because the back of the box actually rests against it.
The dimensions of the box are at the face, 13”Hx10”Wx5.5”D. The notch is 3”D. Because the box only has 2 screws securing it, that area needed to be reinforced on the inside of the box. Regular framing “L” and straight brackets were used to attach the box to the same panel as the fuse holder. I used Does-it-all vinyl adhesive caulking to seal all interior seams and the notch, ends and sides of the box were fiberglassed. Because I did not want to carpet the box, I used bondo and polyester resin to create a smooth surface and coated it w/ primer/sealer. My intention is to either paint it or cover it w/ vinyl to match the interior. The black plastic trim piece that helps support the floor panel had to be trimmed and a strip of foam rubber was applied to the edge.
Power was taken from the terminal block in the battery/spare tire compartment just behind the rear seats. Remote turn-on was taken from the black 12 pin connector on the right side of the factory amp bracket. The signal was taken from the 42 pin connector on top of the factory amp which is speaker level.

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Excellent write up. Thanks for the contribution!

That is one fantastic looking enclosure. How is the final sound?

Thanks NCX. I was having a little trouble with the attachments. I hope all works out.

I'm pleased w/ the sound however, I will probably purchase a high-end driver to replace this one and I'm stoked to build a 10" box to use even more of the below the floor space.

Hello,
You did a great job on the sub box, have you thought about spraying the box with the stuff they spray in the back of pickup trucks for liners? It would be durable and you can get it in several colors like black, gray & etc...... I have a 2001 X-5 with a Non DSP system and I am going to use a factory subwoofer from an X-5 with DSP system that I bought and install it in my vehicle. The approach will be similar to yours except you fabricated your box and I am using the OEM Sub. Would you please forward me the color codes of the wires you used and perhaps provide some close up picture of the wires you used to tap into? Did you use the high level output from the Stereo Head Unit to the Amp or did you use the wires going from the amp to the speakers? Also, did you use the wires from the front speakers or the rear? I wish they sold a aftermarket audio cable and connector that was a plug and play unit for a Non DSP stereo to hook up a amplifier and subwoofer, but I have not been able to find one for Non-DSP. Please advise.

Looks like you did some nice work... since 1/2" is a bit on the thin side, and since you could use some more volume, you might consider fiberglass for the rear "tub" of your next box....

you read my mind. :D

What do you plan to change about the box?
 

I intend to make a custom box for the compartment. You said you want to make even more use of the bottom space. Do you have any pointers so that I take maximum advantage of the compartment space?

Thanks.