Two Subs Vs. One

I agree with Eldartford when at very close range and at higher SPL levels.

I find I become aware of the general direction of a sub when I am within about four feet of it in 25 foot room (very close range and the lower the cut off the closer I need to be to know where it is). This tends to work only at higher SPL levels so maybe floor vibrations are providing higher frequency harmonic clues or it is the small amount of energy from the driver above the cut off....who knows.

I do agree that a sub position behind the listener does not seem to work as well...perhaps because this ends up being quite close to the listener. My preferred option is placement at a similar distance to the listener as the main speakers and for practical puproses to one side of the room or the other (rather than between the two speakers). Sub to ceiling, sub to side wall, sub to rear and front walls all being different lengths (this seems to be a good rule of thumb).

Two subs does complicate things as cancellations will also affect the sound field...probably a harder setup.

Tim916 hits the nail on the head IMO.

I have posted my experience in this thread:

http://forum.audiogon.com/cgi-bin/fr.pl?cspkr&1163160495&read&3&4&

In defense of my statement, find us an engineer please. You may be "feeling" the bass when it is really loud or close. But, hearing it is another story. I'm not a bass heavy person. If you came to my house, you would be hard pressed to find my 15" velodyne, let alone tell if it's on or off unless listening to a track that has lots of deep bass. And yes, when watching a movie, I can localize the bass because it shakes the heck out of my room!

I was always taught a simple sub set-up technique for people without the money or access to test equipment. Place the sub anywhere. Get on your hands and knees and crawl around the room while playing some strong bass pieces. Where the bass sounds strongest or best is where you should move the sub to for optimum room response. Far from perfect but if you can't decide on the final location this may help.

Where the bass sounds strongest or best is where you should move the sub to

And that's usually going to be in a corner. Other factors in the whole one vs. two subs question are (1) where the crossover is set, (2) if your mains are runing full-range or are high passed, and (2) the distance from the sub(s) to the mains. These factors affect a listener's ability to localize the bass.