Old Timer in need of help

[1point21gigawatts]

I will tell you what to buy and what to do and literally draw the plan out and take a picture of it and post measurements and a cut sheet. I can start tomorrow when I wake up. Because I’m so tired right now and once I hear a response from you, I’m eating and going to sleep lol! We are gonna make your son happy. 

[Joshdashef]

2 hours ago, d luv said:

I am open to all suggestions as I am good with working and constructing wood, but have never built a speaker box so I am a total newbie when it comes to the design aspect.

So to try to fit in the space you mention, and allow your son to keep his cargo area depth, the final dimensions I came to are 14.5 H x 36 W x 18 D. Just a bit bigger than the prefab but this time you will end up with 3.056 cubic feet net volume, tuned to 34.95. (I tuned you lower than JL had on their website to maintain the same f3, frequency at which output will begin to be noticeably lower than the rest, to right around 32 hz). 

 

Couple things that I had to do to fit it. 

1. Sorry ahead of time, but I made it out of 3/4" mdf, I know you have a sheet already but 1" all around wastes about 0.17 of a cubic foot and leaves you with only a 1" front baffle. This design gives you a 1.5" front baffle. Feel free to add round overs where you please, in the port and outside the perimeter - it can only help. 
2. I folded the port to allow for even back pressure of the subs, so just take note of that in the sketchup designs. It won't be a standard L port
3. I didn't allocate a ton of port for your box. In a way it can hamper maximum output due to port compression. However, smaller ports tend to have larger bandwidth and since your son also listens to metal on occasion I felt that a port area of 42.25" (13.83" per cubic foot net volume) would suffice and allow for more total net volume. (27 m/s port velocity)

It is important that you put a subsonic filter on the amp at, or above, 23/24 hz. This will protect the drivers from reaching their mechanical limits, aka going too far forward and tearing up your soft parts. 

 

Here are some sketchup screenshots (JPGs can be downloaded on my google drive) and a cut sheet for a standard 3/4" x 8' x 4' sheet you can get cut up at your local Home Depot store with three long cuts and finish the cross cuts at home, or get HD to cut as many as they will. 

 

Cut Sheet Link (PDF)

 

Sketchup Google Drive Link (JPG)