I'm trying to buy a sub for my very open living room, which also has vaulted ceilings. In the picture below, I use red lines to set off the "living room space," but neither of those lines represent actual walls - so the living room really stretches all the way to the dining room wall, and there is only a very thin wall that separates the living room from the den. I would guess the vaulted ceilings - which reach up to the top of the second floor - are at least 20 feet high. So, 17.5' x 18' (which is about half of the wall that leads to the dining room) x 20' = 6300 cubic feet - which is an under-estimate considering the living room just opens into the dining room, the stairs, and the den.
Now, I'm not that into bass, but I just want something to fill out the bottom end of my music and movies. Am I crazy to try and do this with one sub? Both my wife and I would prefer just one. I'm considering the Klipsch RW-12D, HSU VTF-2.4, and the Outlaw LFM-1 Plus. (I realize that if I can find the RW-12D on sale for $300 shipped, I can get two of them for cheaper than the HSU or Outlaw - but again, I prefer to have just one.)
And as a further question, what does a sub sound like when it's placed in a space too big? Does it actually sound bad, or just not up to its full potential?