Subwoofer Solution, v4 (and hopefully the last!!) by H20boy

By diyauto
( 5 )

6 minute read

Subwoofer Solution, v4 (and hopefully the last!!) 

Compliments of H20boy @


A couple of you knew I was working on another subwoofer enclosure option for the backseat of my xk8. Allow me to give you a timeline before I detail the project for what I hope will be my final solution to get decent bass in this car. Note in all scenarios, I had an aftermarket amplifier installed to provide all required power.

Version 1: I replaced the 6-inch OEM woofers with JL Audio 6w0 and then JL Audio's 6w3 units, which were a step up from the original alpines, but not what I was accustomed to having, and needed more of the punch. 

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Version 2:
I had a guy carve the rear seatback cushion's foam and he built a box that fit into it (facing the trunk) and it held two (8") JL Audio 6w3s. Again, it was better, had lots of that tighter bass capability, but not the lower frequencies, and the box sorta bumped out of the seat cushion's leather, could see it was there. Not happy in aesthetics nor performance. (No pics, sorry...lasted only about 3 weeks)

Version 3: I needed a bigger subwoofer, at least a 10-inch, so I bought a JL Audio 10w6, it was one of their top units at the time, and needed the least amount of space for a sealed box (0.625 ft^3) without going to the 10w7, which is their prized sub, and takes a whopping 1.25 ft^3. With the size of the xk8's cabin, I figured a 10-inch would be more than enough, if it was enclosed properly. 

Only problem was I had no room for this, so I thought maybe a fiberglass enclosure, secured to the back seat (via a hidden bracket) would be enough to satisfy me. This was a good solution, and lasted about 1.5 years before I changed it. I could not move/recline my seat back the entire way, and I was annoyed about that. Also, the color of the vinyl they wrapped it in did not match, that bugged me. And finally, the passenger could never feel the same bass as the driver, due to the nature of the installation, and the cushion dampened any 'bass' vibration that could be transferred to the passenger through the car's frame/body.  

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Version 4: I went to my audio shop in Ft Worth (Woody's Car Audio) and their new enclosure guy, James, was touted as an expert in his field. I explained what I wanted -

1. pull out the rear bottom seat cushion for easy re-installation in the future if I want

2. fabricate a subwoofer enclosure behind the driver, that allows me to move my seat and recline fully, use the JL Audio 10w6 in the car

3. keep the passenger side available for children and my dog to use, 150 lbs max weight, seatbelts must still be operational

4. wrap the new 'seat' and enclosure to closely match the original style, and use genuine Connolly leather perfectly matched to the OEM color

Here is what it looked like, original seat -

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Here is what I received, after 1.5 months of their work, in and out for 'test measurements' and final upholstery work. It actually is TWO separate pieces, one is the sub enclosure, the second is the remaining seat. The seat uses the same two (2) fastening points as the original did, he did a great job. 

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Click the image to open in full size.

Click the image to open in full size.

Some 'construction' pics, courtesy of James showing a few stages of the fiberglass work. 

The body and wiring, under the rear seat (driver side)

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Click the image to open in full size.

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Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

I spent alot to get this final product in case you're interested (most are) - over $800 in labor for the audio shop to build/install the enclosure, $50 in shop supplies, $475 for 3 yards of dove grey leather (I have alot left over BTW, PM me for pieces if you want to buy some material) and another $500 labor for the custom upholstery work. 

Result - sounds GREAT, lots of bass, and I have soo much more room for my driver's seat now!!! James informed me that my previous box was WAY too large, I measured the internal volume and found 1.3 ft ^3 available...that last guy didn't know what the heck was going on, apparently. Attic paperweight it now becomes.

James is open to do this again, and it should be considerably less to do a second time, if you so desire. 

Hindsight thoughts

  • I should have cut my original rear seat cushion up, and saved about 1/2 of the construction & upholstery costs. Like I'll ever need to put it back in to sell...not when it looks that good. Oh well, live and learn.
  • Black interior color also would be much easier, and cheaper to upholster, good gracious this dove is pricey to match

Its been done for a couple weeks, and after tweaking the 3sixty.2 for this new setup, I am absolutely thrilled with the overall system. The 10-band EQ for the subwoofer channel really helped tune that frequency range. 

Yay! I'm off to listen to it again over lunch!! For those of you who don't know about the rest of the gear in the car, take a look here for more info.