Originally Posted by thehifidoc
I I like 4 myself evenly spaced around the room to eliminate nodes.
You hit the nail on the head - its not so much the greater amount of bass, though more subwoofers do ease the load and provide more accuracy, its the nodes, the more subwoofers, the less effect nodes have, and nodes are serious problems with just one or even two subwoofers. But its out of sight, out of mind for most.
To understand how multiple subwoofers ameliorate the problem of nodes, consider this:
imagine the nodes of one subwoofer to be like the ripples caused when a pebble is dropped into a pond.
Then drop two pebbles a few feet apart. A person can visually imagine this. Note the ripples intersect, forming a more diffused ripple effect.
Then drop four pebbles each a few feet apart, note that there is much more intersecting ripples, producing a very diffuse effect where the peaks and troughs that were very apparent with the first pebble become much shallower, not only that, but the diffusion will nearly eliminate the "wave" effect. And the more subwoofers, the more even and diffuse will be the ripples.
As with most searches for near perfection in audio, expense and room are the usual limitations.
Dave Ladely in Snohomish, WA, home of Sunfire and my old friend, Bob Carver