The biggest obstacle to natural-sounding bass is the room. Seriously. The room imposes an inevitable, and drastic, peak-and-dip pattern on a subwoofer's output. The peaks and dips are too far apart for the ear's natural averaging-out characteristic to come into play, and moving the sub or the listening position only re-arranges the peaks and dips - it cannot eliminate them. EQ can eliminate the peaks and dips at one location, but will make them worse at other locations.
No matter how smooth your sub's response starts out, by the time you hear it, the room's effect is in full cry. You see, the ear has to hear more than one wavelength of a bass tone before it can detect the pitch. Think of how long bass wavelengths are, and how big your room's dimensions are, and you'll see that by the time you can hear the pitch of a bass note, the energy has already bounced around the room multiple times. You literally cannot hear the sub apart from the room. Sub + room = a system.
Now if you have two subs spread apart an appreciable distance, their in-room peak-and-dip patterns will be significantly different, and these two dissimilar patterns will tend to average one another out. And they will produce a net peak-and-dip pattern that has its peaks and dips closer together, so that the ear's natural averaging mechanism will reduce their subjective impact somewhat.
Generalizing a bit, two subs spread apart will give you twice the in-room smoothness (and half the average variation from one location in the room to another) as a single sub. And four subs will be twice as smooth as two. Todd Welti and Earl Geddes are proponents of multisub systems, Welti focusing more on symmetrical placement while Geddes focuses more on asymmetrical placement.
While a single 12" ubersub will go deeper (and probably louder) than two 8" subs, the pair of subs will do a better job of working with, rather than against, your room's acoustics.
Imo, ime, ymmv, etc.
Duke
dealer/manufacturer
