06 - Stealth Sub

This is what really got me started: I got this used 120 watts RMS monoblock Kenwood amp for only $21.50 from eBay, including shipping. Here it is shown mounted on top of the sensor guard (located under the driver's seat) using sheet metal brackets fabricated from Simpson Strong-Tie foundation straps. The elevated mounts help conserve left rear passenger toe space. I later added another bracket to brace the amp against the drivers seat rail, to force the sensor bracket downwards against the carpet to dampen vibration.

I then ran the required wiring. I pulled my center console to run my wires. I pulled my glovebox door to access the rear of my head unit. I tapped off my accessory socket for my amp turn-on signal.

I ran my amp main power wire inside the left front fender, thru an existing grommet in the driver's doorpost, then down, along the door sill, then to the amp under the driver's seat. I didn't even need to pull the mudguard. I used 14 gauge wire since I had some readily available and since my wire run is relatively short (roughly 13 feet).

Next, following what others have done, I created some additional space under the front passenger seat by relocating the front passenger occupancy computer and related plugs. I did not have to unplug anything or disconnect the battery to do this. This picture shows the plugs already dismounted from the crossrail, and the computer in the process of being unbolted.

This picture shows the computer mounted above the crossrail, the plugs rearranged, and the original computer bracket flattened out.

Also in the photo, my footwell LEDs for the right rear passenger have been moved to the rear of the seat, so they won't be blocked by the subwoofer enclosure.

My goals for my subwoofer enclosure:

• house an 8" subwoofer

• do not block heater floor vent

• as much toe space for right rear passenger as possible

• as compact as possible

Of the 8" subs I looked at, the Rockford Fosgate P1S4-8 needed the least amount of sealed volume: 0.23 cubic feet, plus 0.053 for the sub, for a total enclosed sealed volume of 0.283 cubic feet. My plan gives a volume of 0.287 cubic feet.

Here's the Rockford Fosgate P1S4-8 subwoofer shortly after it was unpacked.

• 8 inches, 4 ohms

• Kevlar reinforced paper cone

• 4.39" mounting depth

• 83.5 dB @ 1 w/m

• 39-250 Hz

• 200 Watts RMS, 400 Peak

• 38 ounce magnet

• 2 inch, 4 layer voice coil

Note the trim ring has no grill...bummer.

Here's the subwoofer enclosure build in progress. I used a sealed enclosure design to save space. I used 3/4" MDF, glue, and wallboard screws. Note the heater vent path.

Here's the underside view of the heater vent path. The "dip" in the middle gives more clearance for the subwoofer magnet thus allowing a reduction in overall enclosure height.

Here's the finished enclosure, with wire. On the outside, I used a 2-conductor Molex connector on the wire as a quick-disconnect.

Since the subwoofer didn't come with a grill, I made my own. I cut and shaped some metal window screen, painted it with a heavy coat of gloss black from a rattle can, then carefully attached the grill to the back of the trim ring using glue from a hot glue gun.

This picture shows the enclosure covered in black carpet and filled with about 1/4 pound of polyester batting, following the general rule of 1 pound of batting per cubic foot of volume. The subwoofer is wired and is ready to install. I got the black carpet from Home Depot and attached it with lots of glue from my hot glue gun plus a few staples.

Here is the subwoofer and trim ring/grill mounted onto the enclosure. Rockford Fosgate includes 8 hex-drive screws plus a hex drive tool. First 4 screws attach the subwoofer to the enclosure, then 4 more screws pass thru the grill and subwoofer into the enclosure. The socketed screws prevent you from sliding off the head when tightening the screw, and possibly poking a hole in your subwoofer cone or surround. Nice touch!

Here is the enclosure in my ride, under the front passenger seat. The enclosure is about to be clamped between the seat rails and the floor pan. I had to make some relief cuts in the factory carpet to allow some of the enclosure corners to fit better. I also trimmed off about 1" from the OEM plastic floor heater vent outlet.

This picture was taken from the front passenger footwell looking rearward. It shows the wires and plugs clearing the enclosure and speaker grill after the front passenger seat was reinstalled. Fore/aft seat travel is not affected.

(The black plastic conduit on the left is to the OEM occupancy computer, and the thinner black wire on the right is for the LEDs mounted under the seat.)

Here is the toe space available for the right rear passenger. In this picture the front passenger seat has been moved all the way forward. Note the heater vent outlet in the center of the picture.

As of this writing, the subwoofer is well broken in, and it sounds great!

Plus, the subwoofer makes the right front passenger seat...well, Special.