Any audiophiles here? Need your advise

I could try that , I've never worked with bondo or fiberglass but I like to learn new stuff, does the JL specs for sealed enclosure (19x15x7.75) fit there? Also I've seen some people add some spray on bed liner like, to give it a rugged style, I don't know if this is good for acoustic also

 

It doesn't matter what you put on the outside of the box it will not change the sound. You can cost the box with Berliner or anything else you want to use. The box on jl website won't fit behind your seat but that doesn't matter the important part is the internal volume of the box as long as the internal space is around 0.8-0.85 cubic feet you will be fine best to measure the maximum area behind the seat figure out the volume of that then adjust your box size unroll you have the correct amount of air space inside remember when measuring to leave enough distance from the speaker to the seat that the sub won't hit the plastic on the seat back when playing. There are some good speaker box calculators online if you need one. O e of the best is on www.rockfordfosgate.com you enter your measurements and wood thickness and it will tell you the internal space available.

 

I know the whole cubic space is what matters most but the internal dimensions are also important aren't they? I mean the sound wave will not rebound the same if we change the width or the heigh or the deepness of the box, what box dimensions have you used for your 13TW5 installations that have had better results?

 

And for the speaker not to hit the plastic behind the seat I had thought to add a 1" or another 3/4" MDF in front of the box with a 14" diameter cut-out to give the subwoofer a little more depth and protect it agains hitting when it's at max outside excursion, what do you think?
Also this extra wall thickness will make stronger the speaker box right? I don't think a 3/4 MDF will bend with a 13TW5 but anyway it's a plus to add another 1" or 3/4" of strenght on the front I guess

 

Yeah you can do that, if you just make sure to build the box shallow enough that the sub is a couple inched from the seat you'll be fine too, as for the box no changing changing the shape won't cause problems the box on the web site is just an example of one the right size it isn't a requirement to build it that shape. It will sound just fine in the shape that fits best behind the seat, I actually usually try not to build he box for any sub perfectly square I usually think subs sound a little better in a box with at least one angle. There really isn't a noticeable difference though.

 

That's good to know, thanks for the info I'll take this in consideration when the sub box is being made, and maybe I'll post some pictures of the process for you all to take a look and judge so you can give any positive or negative feedback
One more thing, I've seen some boxes that uses some kind of filling inside, what is this for?