Wayne Parham Messages: 18787 Registered: January 2001
Illuminati (33rd Degree)
Subs act differently than mains or surrounds, since they energize (only) the room's modal region. And they're omnidirectional too, like you said. In this case, it's the room that creates the "directionality" in that it causes a "polka dotted" sound field because of interactions with reflections.
All that said, subs work best when distributed. The ceiling would be fine for one of them, maybe even a couple. The main thing with subs is that we spread 'em around.