Help with my subwoofer box. Need a box designer!!

[Tjwubs34]

So i took a swing at building a box for my brand new FI sp4 15" v2. And it sounds terrible. Currently the sub is wired to 2 ohms on a soundqubed 3500. I am running stock so once i upgrade my power ill wire to .5 ohm. Anyways i used the box program called Torres and i think its inaccurate because the subwoofer doesnt hit hard at all. My old Sundown x 10 hit harder. First i thought it was my amp settings. I have my subsonic at 20 hz, my lpf at 50 hz, my bass boost at 0, and my gain at about half. I sort of think its just my power. I know this is a 4" coil and will require alot of power so maybe it is not coming "alive" but this is the quietest sub ive ever owned. And yes its wired right i checked with a multimeter its wired to 1.8 ohm. Let me provide my torres box specs and if someone can check if its right that would be very cool. And also provide a better box that will fit this sub. My car space is 39" wide, 18" high, and 23" deep. i drive a hatchback so its 18" to the bottom of the back window. Heres my box specs based off torres....

Box is:
32" Wide
18" High
23" Deep

Port is:
4" Wide
16.5" High
31.5" Long (its an L port. The first peice is 19 inches long and the 2nd peice is 14 long)

Torres says with my threaded rod bracing, my subwoofer displacement of .21 cuft^3 and my extra baffle (the sub is on top i glued 2 layers of 3/4mdf together for the top) box is

Tuned to ~31HZ
Port Area is: ~66 inches of port area
Box size: 4.4 Cuft^3
Which puts it at roughly the 12-16" port to box size range....... Is torres accurate? I literally wasted $70 on this box with the time and work. If the box is correct i know its my power or maybe i bought a bad amp.... If its the box i will make a new one if someone can provide a better 15" sp4 box... Im going for the lows and decent highs. I figure 31hz is pretty good place

 

Thanks!!!!

[ShadeTreeMechanic]

You will need to set your gain with a dd1 or an O scope to get the most out of it. I tried running at 2 ohms one time. I wasn't impressed either.

[neuspeedescort]

how did you tune your amp? "gain at about half" means nothing.

why is your LPF at 50?  that is quite low unless you have some killer midbass.  bump it up to 80hz.

what shadetree said also.  get that ohm load down.  2 ohm can be unimpressive.

[Tjwubs34]

1 ohm 2 or or half ohm i kind of need an expert on box building to tell me if my box is even good enough at all..... i honestly believe its the box, or the power. But mostly the box for right now. Even little power should still show me something. 

[DLHgn]

The box seems fine to me but I couldn't really tell you until I got to my personal computer. I would give the box a chance and see how it performs with the sub wired down and the gains set properly. Again, I can plug all your specs into WinISD later and see how it all charts out but I would just give it time.