15"s are basically capable of playing lower frequencies than a 12. When I went from a 12" to a 15" of the same exact model, I noticed that it was a little louder, but really it just played a lot lower. Sounded nicer overall. Why do you think a 15" is more expensive than a 12"? Because the 12" sounds better? That doesnt make sense //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif