Does anyone know how to make one or where I could get some plans? Its only for my computer..but I want alot of bass..I was thinking of going with a 4th Order Ported Enclosure. The driver I was gonna use is a 10" Poweracoustik subwoofer.

mpja.com has it for $44.95 http://mpja.com/productview.asp?product=14981+SP

Another thing I would like to know..is what is spl and mag? and for the amp..I was just gonna design my own..probably 100W or something..JUST for the SUB. My Speakers (and mobo) do have sub out..but I dont think it would be enough to drive that thing. The sub out on my mobo would need an amp....the sub out on my speakers is already amplified I think..

First, if you are going to be running a subwoofer of the type you are looking at, you are going to want a 2nd (sealed) or 3rd (ported) box. A bandpass (4th, 5th, and 6th order) box will produce a finite range of frequencies, while the other two will run a much larger range of frequencies.

Found it here cheaper.

After looking up all the specs, you're best bet is to build a 2nd order (sealed) box that has .75 cubic ft of air space. Let me know fine PM if you want me too design one.

I also looked up the power rating on it. 250W RMS @ 4Ω This means that you need at MINIMUM 250W @ 4Ω to run it correctly. Any lower than that, and you will greatly decrease the life expectancy of the subwoofer.
The amplifier I can not really help you with since you are thinking about building one, but my suggestion is this amp run on a ac to dc convertor. You will also have to rig up a 1.5V "turn-on" lead that will tell the amp to come on.

Wire it up in mono (bridge the channels by using the + on one ch, and the - on the other.), and you will have enough power.

PM me if you have questions, or IM me on AIM, since I am on till at least 4 CST.

Tom

EDIT: That turn-on lead voltage might actualy be even lower than that. I will see if i can get a multimeter when i get home and check to see......