Concrete Sub Box

I have a 95 Nissan Kingcab, putting 3-15" powerbass extremes in the bed firing thru a crawl through. The guy that designed the box told me to put sonotubes (16" concrete forms for pouring cylinders) inside the box. The box is sealed and the corners have been fiberglassed so that they are curved instead of square, the outside of the box is concreted. Has anyone seen this design before or had any luck using the sonotubes. I've built lots of boxes but have never seen the use of tubes inside a sealed enclosure. Thanks for the help guys!

wouldnt a concrete box weigh ur car down a ton?

ok, this guy who used concrete.... does he have a clue what he's doing? Concrete is like OldSkooL sound deadener used back when my dad did this kind of stuff. Concrete shouldn't be in installs nowdays as its 1)too freak'n heavy, 2)hard to work with and 3)not as good at what its suppose to do as actual deadnener like Dynamat etc. And why he wants you to put tubes in your box well my only guess would be that he either didn't use internal bracing and just didn't tell you that the box is weaker then it looks, or that he made it too big and needs to fill air space. Seriously recheck this guys stuff as it makes not sense to me."Shiny chrome when used in conjunction with bikini models is particularly effective in inducing brain deficit disorder"

02 Jeep Grand Cherokee

Monster System on its way.

I'm guessing the box was designed to imitate a tool box and extends from side rail to side rail in the bed, so the forms are used for both structural support and to take up air space.  And is this a design, not an actual built product?  But you can't connect the bed to the cab, because a truck flexes at that point.  Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

not always....grin

ah, a slick grin coming from the guy who's building a sub enclosure into the a truck cab from the bed at the meeting point haha."Shiny chrome when used in conjunction with bikini models is particularly effective in inducing brain deficit disorder"

02 Jeep Grand Cherokee

Monster System on its way.

Don't put concrete in a box, especially if its not secured (or else it'll be bumpin and grindin like R Kelly, on your sub, and no, thats not a good thing). If you need to fill airspace then use some mdf and just screw it in layers on to the back or sides. Also I would definitely consider bracing your box (it's a must for SPL applications especially).  

so this guy hasn't heard that fiberglass is weather resistant or something?"Shiny chrome when used in conjunction with bikini models is particularly effective in inducing brain deficit disorder"

02 Jeep Grand Cherokee

Monster System on its way.