Spare Tire Subwoofer Fabrication

[FABombjoy]

Thought I'd share my latest project - a subwoofer enclosure for the spare tire well.

I'm pretty terrible at fiberglassing but it doesn't stop me from trying I've built 4 different enclosures for my car now. The first two were failures, the 3rd was a lockbox sub for behind the driver's seat built in 2006. For that, I used a Kicker 10" Solobaric.

With the lockbox sub, I was never completely satisfied with the sound. It was plenty loud but the space constraints meant a box not optimally sized for the Solobaric. I prefer quality over volume so I knew I'd be revisiting things eventually. Also it seems challenging to have a large driver in an small cabin yet still retain quality. I've always preferred to get the sub out of the passenger compartment and use the car's transfer function.

Using the spare tire well was an appealing solution but I was skeptical about shallow-depth subwoofer sound quality. I'd originally envisioned using the JL 13TW5-3, but recently revisited the idea and found this MB Quart RLP-304 which had good reviews at a fraction of the cost. The 304 is about 3" high, and the tire well is 6" high, leaving plenty of room for the pole venting and a grille. Unlike fitting the lockbox with a larger driver, the total volume of the tire well makes constructing an enclosure that meets the driver volume requirements fairly easy.

Anyway, it was about a 2 week process from start to finish. The results were definitely worth the effort. The frequency response is considerably lower and flatter overall. I may switch to the JL driver down the road (if I find one for the right price) but I'm impressed with the MB Quart price/performance ratio. There is a little body tub resonance which I'm going to try to dial out by EQ but will probably necessitate some acoustical dampening.

So far, the two big rattle points are the jack storage cover and the brake access panel. For years I'd left the screws out of the brake panel after having a couple of them seize in the rivnuts. The panel always stuck itself back in place and never let water in, so replacing the screws was never a concern until now Even at the lowest volumes, it was pretty audible, so I ordered a bag of nylon M5 screws to put the panel back in place without seized screw concerns.

I also left out the backing board to the carpeting. It's kinda warpy anyway and would definitely buzz/rattle. The enclosure and grille are level with the trunk, so with the carpeting installed and volume off, you'd never know this thing was in there.

Attached are a few crappy cellphone pics, more build pics here

Tire-Sub.jpgTire-Sub---Installed.jpg

[awildermode]

Very cool.

wooferspare.jpg

[FABombjoy]

Haha, it would probably function better than my stock spare

I'll spray some undercoat on the outside so it can double-up as a "super-duper ultra low profile spare"

[DavidProehl]

Potentially a dumb question:

Can you hear this sub while sitting inside the car? Or is this only for listening to music while parked? I imagine some of the thumping would get to the cabin, but I wouldn't have expected it to be comparable to a sub in the cubby behind the driver's seat.

[FABombjoy]

Yep, it's quite audible in the cabin. Not much different sounding from a typical passenger car with a sub box in the trunk.

I also have 6.5" components up front which are good to about 50hz or so, so the sub is really only for about 80hz and below. I'm still playing with the crossover points to find the best results.

If you combined this kind of enclosure with stock 3.5" speakers there would probably be a significant gap in mid-bass response.

[DavidProehl]

Excellent! It is a great idea, and looks fantastic. I recently got the enclosure for the cubby, but this looks like an even more invisible alternative.

[NightFlyer]

For years I'd left the screws out of the brake panel after having a couple of them seize in the rivnuts. The panel always stuck itself back in place and never let water in, so replacing the screws was never a concern until now Even at the lowest volumes, it was pretty audible, so I ordered a bag of nylon M5 screws to put the panel back in place without seized screw concerns.

WTF - No Pozidrivs?!?!?

BAN HIM!!!!

J/K

Looks interesting - can't wait to hear this in action

[FABombjoy]

WTF - No Pozidrivs?!?!?

Haha, I still have like 90 nylon M5x15 screws left, so you're welcome to a handful when you strip out your seized originals

I think you are the only other Delorean owner that had heard the old sub. I'm sure you'll agree this is a big positive step.

Excellent! It is a great idea, and looks fantastic. I recently got the enclosure for the cubby, but this looks like an even more invisible alternative.

Thanks! The cubby solution is definitely more practical, but I just had to get those low-low-lows sounding better

In other news, if anybody is interested, now taking offers on a cubby enclosure w/ Kicker L5

Cubby-Kicker-L5.jpg

[Josh]

Since its a custom piece, not really sure what to offer. But I am interested in the cubby enclosure.

[FABombjoy]

I'm not looking for much, shoot me a PM and I'll go over the details. It wouldn't be too difficult to adapt it for a different speaker as well. It's stoutly built but definitely the work of a composites noob