What degree of the enthusiasm comes from "I did it myself" vs "wow, this sounds better than the PB-12"?
Enough that I am trying to sell my JTR Triple12 main speakers so I can build a DIY option at which point I can gladly proclaim after my guests are wowed that "I built every speaker in this room myself."
Bottom line, DIY>Commercially purchased subs DOLLAR FOR DOLLAR. You can't expect to spend $500 on a DIY driver/amp/box and expect it to best a $2500 seaton submersive. I know that is well above your budget, but I am just trying to make a point. As others have stated, the benefit in your case to going with an already assembled unit would be someone else has already done the "tinkering" for you, but one major thing to consider is that it might mean NOTHING if your room doesnt play well with what the company has already done.
Your room is pretty big, so it will take a little more than some of the builds you might run into. DD has a good suggestion with the f-20 and I can attest that while you CAN tweak it, you dont need any to have it sound absolutely incredible. I ran a pair for about a year and never messed with them until I just did it for giggles, not because I was unhappy or they didnt sound right. Lilmike, the designer of the f-20 did a great job and the directions to build are virtually dummy-proof. Bang for the buck, you won't be dissappointed. It IS a big enclosure though, you seem to have the room however
Most sane people would say the f-20 has more than enough output to make them happy, and yes, it doesnt lack in the "detail" field as well.
If that looks a little beyond your scope of building skills, consider Erich's pre-cut subwoofer flat packs that he is offering (www.diysoundgroup.com
). He may be putting the site down for a little while to get some stuff shipped out, but he has got some GREAT stuff there that you could buy, at which point you would just have to simply assemble the box. No cutting necessary, and then choose what type of driver(s) you want to pop in there. Sealed enclosures are going to be the easiest build, but to get really substantial performance, you need more actual speakers, and more power from your amps to drive them to match the output of a ported box or a horn-style enclosure. I would say at least two sealed 15's to get you started. Should you decide in the future you need more bass, you just build two more
With a ported sub, you are going to get more output, but wont be able to dig as deep for movies. They also tend to need a little more tweaking if not done properly.
So a quick and dirty rundown? Sealed is easiest and best, but you need a lot more of them, and it is more costly to get there. Ported is a happy medium if you can sacrifice some of the super low-end, as most commercial offerings do, and are a step up on the wood-working skills. Horns are the largest footprint and take a little extra work to build, but really belt out the bass if you are ok with the extra time and space they take up.