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Building My Own Stealth Sub Box

14K views 35 replies 6 participants last post by  freemind 
#1 ·
I'm only about half way done and not even sure how it will sound.
I really don't feel like spending $135 on a Subthump, or close to $600 for the JL stealthbox. Figured I would spend $20 and build my own.
I started by removing the driver side hatch carpet.


measured up and cut the face and top and dry fit it.



than the back.


Still need to figure out the front against the seat, seal the seams, cut the hole for the sub, and I think I'm going to just fiberglass the depth to fit snug against the inside since there are too many angles to try cutting.
I'll post the pics I take tomorrow of the final half and give measurements if anyone wants them since I couldn't find any elsewhere.
Comments and input welcome, but go easy if you think it's stupid.
 
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#2 ·
Looks nice. What sub are you putting in there?
 
#3 ·
I got a 12" autotek meanmachine.
It was cheap but it sounded good in my old box. I'm not trying to blow my hatch glass out by any means.
It's got a mounting debts of 5.5" so I might adjust the depth of the box to give more hatch space. It only sticks out past the opening by about 4-5".
 
#4 ·
How did you measure the air space that the sub needs with all of the different angles of the car? How are you sealing the box completely if the back is open to the sheet metal of the rear wheel well?
 
#5 ·
he said he was going to use fiberglass on the back edge. as far as the volume goes, it will be difficult but you can get a "close enough measurement"
 
#7 ·
Ahhhh, I can't see those comments on the picture, but I have been having problems all night, my bad for asking something that he posted, I was just curious from only being able to see pics on how the volume was going to be determined. Definitely need to post some pics of the finished product. I always like to see how custom boxes turn out
 
#6 ·
Like I said, I'm not sure how it will sound.
I plan on making a fiberglass mold against the body panel and attaching it to the mdf making sure it is sealed.
The sub only needs 1 cubic ft of air space. I'm hoping I can figure that out after fabricating the mold against the side panel.
I'm thinking of sound deadening the side panel before making the mold so nothing vibrates.
 
#8 ·
^ lol no worries!
This is my first attempt at a custom box.
Also my first hatchback as well.
Now that I'm not 16 anymore I'm not looking to take up total trunk space with subs in a simple square box like back in the day.
I know most stealth boxes work best with 10" or smaller but subthump makes one for a 12 so why can't I do it for $100 cheaper!!
 
#9 ·
I agree, and I always have more fun building my own anyway, this is on my project list for my '12 but probably not for awhile, I have some other things that need to get done first.
 
#10 ·
If this works out and sounds good as well, I'll duplicate it and put one up for sale. I bought a 4x4 3/4 mdf and only used half the sheet with nearly no waste. The cost will be in the labor and fiberglass. guess I'll see when it's done.
 
#11 ·
You can measure the volume of the enclosure using packing peanuts. Fill the enclosure with peanuts and then, transfer the peanuts into cardboard boxes of known volume to get the actual enclosure volume. A 12"x12"x12" cardboard box = 1 cubic foot. The rest is easy.

I can't wait to see the finished box!


You can use strips of soft rubber under and behind the enclosure to decouple(isolate) it from the body of the car. I am giving up old tricks here!
 
#12 ·
that's a good idea with the packing peanuts.
 
#13 ·
Auesome! Thanx for the tips!!
As for sound dampening, I have about 4 100ft rolls of butyl rubber but they are only 1 inch wide. I might as well use it on the wheel well side since it's been sitting in a box at work for two years or more not being used. Cheaper than Dynamat and easier to stick where I want it.
I'll post up more pics here in a few hours when I get started again.
 
#14 ·
Got a bit further today.
Masked off my electrical and tacked some rubber material to the wheel well to use as a backer for the fiberglass. IDK just thought it sounded like a good idea. If it wants to vibrate at least it wont be fiberglass to metal.



Than taped up some fiberglass mesh and started to coat it.


Than I fit the mdf back in to see where I needed to overlap the mesh to attach to the box.


Than coated the rest up to the mdf from inside.


This part just seems ghetto and may look that way as well, but I didn't know what else to do. I will add a few more layers of resin to thicken it up before I attempt to pull it out after it dries. This is turning into a bigger project than I imagined....
 
#16 ·
No, there's a rubber liner material against the metal. Once the resin is dry and attached on the inside of the mdf it should pop out. the box is a very tight fit so it won't move around.
 
#18 ·
The mold popped right out with a little pull. Now just gotta build up a few layers so it's strong enough. After that seal the seams from inside and wire it up.
I couldn't find a carpet remnant to match but I'll keep looking or go with black.
 
#21 ·
Absolutely


Applied a few coats of the amazing FlexSeal spray on rubber.





Still needs layers of resin inside and on the bottom in the back.
It's a slow process since I'm only working on it while at work.
 
#23 ·
^ I just might seeing I have to add some around the edges to seal it to the box better. Might as well go all the way around! This thing is gonna be a beast for weight after I'm done tho. I just hope it sounds good.
 
#24 ·
Almost done with the box. Added some layers for strength and sealed up the seams from inside. Just test fit it again today and it fit nice and snug. I should be able to wire it up and test it tomorrow.
Gonna carpet it next week if it sounds good. If it don't, that was a big waste of time.
 
#27 ·
Yes it's 1 cubic and I foam insulated inside and cut out as close to that as I could.


I wired it up and tested it out.
It sounds a lot better than the box I was using.
Now just need carpet to finish er off.

No rattles other than the little bit from the hatch door trim. I used rubber gasket under my license plate so that don't rattle.
 
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