Have a custom sub box? How is it anchored down? Post pics.

[mikes2017gt]

After a few years of having a JL Audio Stealthbox bolted down in the factory location in the trunk, I'm getting ready to build a custom sub box that will mount behind the back seats. i'm planning on using the center bolt for the rear seats to anchor the box down, but I really have no idea how I'm going to actually do that.

So I thought I'd start this thread so people could post pics of how they've got their sub box bolted down. It would be a pretty useful repository to have, considering how many S550 owners have a sub in the trunk.

Please post any pics you think might be helpful. There's usually more than one way to successfully accomplish something, so if you tried something and it worked, please post a pic.

I'd be a bad OP if I didn't post a pic, so here's my boring pic of my Stealthbox in it's home. It's bolted to the floor and corner behind the taillight using factory mounting points.

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[Cathul]

I use lashing straps attached to the ISO mounts for child seats. Make sure to strap them down hard and tight. Don't bolt into the floor as the tank is right beneath that area. Too risky.
You could bolt it to the metal above right behind the seats, i.e. an upside down bolt, but only if the enclosure is tall enough.

For this i would take some metal pieces, drill holes into it aligned with holes in the metal above the enclosure and cut some threads into it. then bolt down from the inside of the box. Use at least two metal pieces with two bolts each to distribute the load. Use washers to get it sealed.

 

[mikes2017gt]

That's a great idea. Some metal L-brackets bolted to the top of the sub box and attached the metal brace under the rear deck.

This part here, circled in red.

Put some threaded inserts into that brace and bolt the box to it.

Definitely want to see pics of how folks have their sub mounted, so post'em up!

 

[shogun32]

or just buy an enclosure that's designed to fit exactly into the hole.
https://www.zenclosures.com/2015-Mustang-Subwoofer-Box-p/mustang15t3ff.htm

 

[MegaG]

People anchor their subs down maybe that was my problem...

 

[mikes2017gt]

Anything loose in a vehicle is a potential projectile in an accident. Some things you can't avoid but are less dangerous: Cellphone, coffee cup, soda bottle, purse, gym bag, etc. Even those small things can bang you up in an accident.

Now take that 16oz soda bottle and upsize it "just a little bit" to say, 50 pounds or so. Or 200 pounds.

AFA unsecured sub boxes go, I have personally seen:

Huge bandpass box in an SUV slide forward and bend the rear seats in half after an accident. Box with 2 subs and amps attached to it put a hole in the rear fender of a sedan after an accident. Small, sealed box in a hatchback somehow launch itself up and break the rear window of a hatchback during some spirited driving.

IMO, in an SUV, bolting the box down is a life or death choice. End of story.

In vehicles with a separate trunk, it's a serious gamble. I can tell you that your insurance company will not pay for damage caused by non-stock equipment banging around due to an accident. In fact, insurance companies suck when it comes to paying up if your system is damaged or stolen simply b/c it's not stock. They view it the same way as you left your laptop/bag on the seat and someone broke the window and stole it. You pay your deductible and they pay whatever you have for comprehensive insurance for "Items left in vehicle" which is pennies on the dollar.

Velcro can be crazy-strong but I wouldn't trust my life to it. Bolts/screws can fail too; there is almost no 100% foolproof method of bolting things down in a moving vehicle. But metal has way more shear force resistance than Velcro, so that's the way I'm going. You need to stack the odds in your favor.

 

[Cathul]

That's a great idea. Some metal L-brackets bolted to the top of the sub box and attached the metal brace under the rear deck.

This part here, circled in red.

Put some threaded inserts into that brace and bolt the box to it.

Definitely want to see pics of how folks have their sub mounted, so post'em up!

No threaded inserts, but put some metal brackets in the hollow area and bolt the enclosre through the metal into the brackets with two threaded bolts each. This way you distribute the force over a larger area and the shear force needed to rip it out is way larger due to the larger area, similar like Marc is doing in one of his videos (he bolts to the bottom, not the top, but the principle remains the same).



Got my blueprint from Marc last week. Friend of mine will build the box within the next two weeks.
I'm so excited.

 

[mikes2017gt]

I've watched that video at least half a dozen times. GREAT usage of the stock rear seat mounting locations. I'm very paranoid about the sub box moving (as if you can't tell) and possibly becoming a projectile in an accident. Nobody "plans" on getting into an accident...that's why they're called accidents!

Thanks for posting a pic of your custom build specs; your top/bottom measurements of the slanted back are within 1" of mine. Knowing my expertise with numbers, yours are probably better to go with. What sub are you using?

That's the same style box I'd have him design for me, if I went that way. I'm going to try and design it myself. This is probably the 20th box I've ever designed in my life...not my first rodeo.

I'm in the beginning stages of designing the box for my 12W6. I have the max overall dimensions (and the resulting airspace is too big...a good problem to have). But now I need to downsize the box while keeping the port the same area. You know how it goes. Change one dimension by an inch and the whole thing goes to sh1T. LOL! That, and I've never done a trapezoidal box before. Only your standard square boxes from tiny to massive.

The math SEEMS easy, but then you have to start making cut sheets and the angles and well, I'm not very good with numbers. You give me a diagram/schematic and I can fix it or build it. But numbers and I don't get along. At all.

 

[Cathul]

Remember, my box is for a JL 10w3v3, so a good bit smaller than the 12w6. Guess a ported enclosure for a 12w6 is a good bit larger, so i would think about going sealed for the 12w6, especially if you've got enough power to drive it. Go a little bit larger than recommended though. JLs usually like a bit bigger enclosures than specified by JL.
F.e. WinISD recommends 40Liters sealed instead of 29 as recommended by JL. Differences between both volumes are small though. If you add cabin gain you get an almost perfectly flat response down into the mid-20Hz. with a 30 liter volume enclosure in the simulation(don't know how many cu ft that is... we use the metric system over here ;)). And you can feed 700 Watts of power into the driver to reach Xmax at 20Hz.

 

[NGOT8R]

After a few years of having a JL Audio Stealthbox bolted down in the factory location in the trunk, I'm getting ready to build a custom sub box that will mount behind the back seats.

Is your Stealthbox not hitting hard enough for you, or are you just going for a different look? I just installed a Stealthbox in my 2019 Bullitt and it hits very hard with just a 300W micro amp pushing it. I did however, remove the left speaker in the rear deck to allow the bass an avenue of escape from the trunk and that worked perfectly.

 

[4sdvenom]

I wish JL Audio made left and right stealthboxes! I love how clean they look but I want two 10" subs.

 

[NGOT8R]

I wish JL Audio made left and right stealthboxes! I love how clean they look but I want two 10" subs.

I hear you. My JL Stealthbox sounds far better than I had anticipated. I was worried about bass being trapped in the trunk, (based on experience from a previous vehicle) and that’s why I removed the left rear deck speaker to serve as a port. To be honest, removing both rear deck speakers would probably be even more of an improvement, but for my needs, removing just one speaker was more than enough. I also have the ability to dial in tight or very low and deep bass with a remote bass knob.

 

[FreePenguin]

made a wedge, lol fit perfectly on top of my dual jl box. I can tap it out with hand, and gently tap it back in. doesn't move, hasn't moved in like 5k miles. cant physically move though because well box cant tip over.

I got a little piece of wood short of the height, and then bought 5 bucks in leather looking vinyl at hobby lobby and wrapped it a few times, to make it squishy but firm. gives enough just enough to compress and stay fit.
https://www.mustang6g.com/forums/th...nal-from-stock-amp.142090/page-9#post-2919514

I sold my JL stealthbox and went to the dual tw1 box. no regerts

because I cut my weatehrtech mat to fit the JL box in past, I decided to make a little piece of wood/wrap it as well and use 2 L brackets to mount into factory subwoofer holes and on the wood block. to make a storage area so stuff dont roll around

I havnt got a new photo, but I also added vinyl leather to the cutout area, so it isnt grey carpet, its all same material / vinyl Matt I can remove and wipe out and set back in.

it was fun, cheap. got like 20 bucks total in everything

 

[Cathul]

If the box is not bolted down or tightly secured with straps it will move in case of an accident.

https://www.golf2forum.de/thread/1545-folgen---subwoofer-nicht-korrekt-befestigt-achtung.html

Text in this link is in German, but you can still see the pictures.

 

[FreePenguin]

If the box is not bolted down or tightly secured with straps it will move in case of an accident.

https://www.golf2forum.de/thread/1545-folgen---subwoofer-nicht-korrekt-befestigt-achtung.html

Text in this link is in German, but you can still see the pictures.

well to be fair, if theres an accident my seats are up, isnt going through the seats. and I dont have a glass for it to eject out of. Lol I will just buy a new subwoofer box if ever happened. that photo causes me no concern with my setup.

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