Modify JL Stealthbox to fit convertible

[Benjamin Hundred]

Hey guys, I’m looking to add extra bass to my 2018 Mustang convertible. I was looking at the JL Stealthboxes and they’re a 12” sub, does anyone have any experience or ideas about modifying the box to fit a convertible trunk since it’s made for the coupe and they have a different trunk slope angle. Thinking something like cutting the corner off and reconstructing it somehow to seal off. Any ideas on how to best do this would be greatly appreciated. Otherwise I’ll just use a OEM B&O 10” enclosure with a JL sub and dedicated amp.

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[Bassackwards]

If you are going that far you may as well just build from scratch. The jl is pretty expensive and there is a risk that you can’t find anything that will bond to it if it is some type of plastic.

 

[Evolvd]

The JL stealth box is a composite construction and pretty expensive if you’re just going to chop it up. As stated, if you want to utilize that space you’d be better off with a custom build.
I’d also recommend not using an OEM sub box for a JL sub. Slapping in a sub into the wrong sized box won’t do it any favors and with the pressure output of many aftermarket subs will outperform the structural capability of the cheap plastic box the premium system comes with.
Any particular reason why you’re considering these options or JL as the only option? There are dozens of excellent subwoofer brands and models available and it seems like you haven’t put much thought in matching the sub to the application.

 

[Canadian Crimson]

There is a thread here of someone who custom made a box to fit the same location out of plywood,carpet &resin

 

[S550HPP]

I would minimize your spend and effort if don't have DSP amp. Just sound deaden and poly fill OE enclosure first. If adding amps it's a lot of work and cost with great outcome.

I just added Kenwood XR1000-1 amp to my Audison AP 8.9, on a JL sub in OE 10" enclosure that I sound deadened every inch of, inside and out plus polyfill.

Inside sound deadening took a lot of time with all the small pieces between the structural elements. In hindsight two layers of deadening on the outside and just the interior around the sub opening would be fine.

The bass hits very hard. Light years better than when I used 2 ch bridged for 130W to the sub.

Pretty much need 500W+ to a convertible sub to get good sound throughout volume range.

Just buy whatever sub amp can get a deal on. I did carve out a section of the trunk foam near the rear of the foam to mount the amp on a 1/4" Alloy plate cut exactly to amp size and bolted through foam. Only because I need all the trunk space.

 

[Bassackwards]

There is a thread here of someone who custom made a box to fit the same location out of plywood,carpet &resin

That was me and a few pics are available.

 

[Benjamin Hundred]

Thank you for all the replies,

I was looking at the JL Stealthbox because I was offered one with a 12” sub for $300, if I was able to modify that box for that price I’d go for it. Sounds like it’s more trouble than it’s worth.

I’m most likely going to just use the B&O box I have with a 10” shallow mount sub. I’ve researched it and from what I’ve found and what other members have suggested it should work well as long as I go with a shallow mount. The sub and amp is only about $350 from my guy so I feel it would be a good fit for the price and considering other members have had a good experience experience with this setup.

I eventually want to have a custom enclosure made and dynamat the entire car and with a completely custom sound system, but that’s not a urgent need for me, just a bit more bass for now and I’ll be good.

 

[S550HPP]

You can get more bass that you'll ever need from 10" with. 400W+ RMS. I do suggest a remote bass dial so when top is down you can compensate.

 

[Evolvd]

Thank you for all the replies,

I was looking at the JL Stealthbox because I was offered one with a 12” sub for $300, if I was able to modify that box for that price I’d go for it. Sounds like it’s more trouble than it’s worth.

I’m most likely going to just use the B&O box I have with a 10” shallow mount sub. I’ve researched it and from what I’ve found and what other members have suggested it should work well as long as I go with a shallow mount. The sub and amp is only about $350 from my guy so I feel it would be a good fit for the price and considering other members have had a good experience experience with this setup.

I eventually want to have a custom enclosure made and dynamat the entire car and with a completely custom sound system, but that’s not a urgent need for me, just a bit more bass for now and I’ll be good.

Are you dead-set on having the sub in the side pocket area? If not here’s another option for you: https://www.zenclosures.com/2015-Mustang-Subwoofer-Box-p/mustang15convertible.htm

 

[NGOT8R]

Thank you for all the replies,

I was looking at the JL Stealthbox because I was offered one with a 12” sub for $300, if I was able to modify that box for that price I’d go for it. Sounds like it’s more trouble than it’s worth.

I’m most likely going to just use the B&O box I have with a 10” shallow mount sub. I’ve researched it and from what I’ve found and what other members have suggested it should work well as long as I go with a shallow mount. The sub and amp is only about $350 from my guy so I feel it would be a good fit for the price and considering other members have had a good experience experience with this setup.

I eventually want to have a custom enclosure made and dynamat the entire car and with a completely custom sound system, but that’s not a urgent need for me, just a bit more bass for now and I’ll be good.

I crossed this bridge with my 2013 GT stereo upgrades. I actually kept the factory 10” sub and put a JL Audio 300W mono amp and an Audio Control DQ-61 processor on it. This sounded great and to my surprise, one day the speaker loosened all the way up and the bass was much deeper and it sounded even better. I never run my volume more than 75% on any of my car stereos. Let me know if you’re interested and I can try and locate more pics of that install which may be of help to you.

The Dyna Mat idea mentioned above is also a great idea. I never thought about adding it to the I side of the sub enclosure, but I did add it to the exterior on my 2019 Chrysler 300 sub enclosure with poly fill.

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