Subwoofers aren't easy. Sure, adding a decent subwoofer to a system to supply more bass is no big deal, but getting the best possible sound out of a subwoofer is. I've written a few How To Set Up A Subwoofer articles and blogs in my time, but Brent Butterworth's recent "Subwoofers: 4, 2, or 1?" feature in Sound and Vision magazine tackled one of the more difficult aspects of home theater setup: do multiple subwoofers offer any performance advantages over a single sub? Butterworth's premise was simply this: Should I spend my $1,200 subwoofer budget on one kick-ass subwoofer, two pretty good midsize subwoofers, or four little bargain subs?
Butterworth thinks that comparing different sized subs, even when they are made by the same manufacturer is nearly impossible, "Say you compared Brand X's 15-inch sub to four of its 8-inch subs. Well, what if the driver in the 15-incher kind of sucks? Or what if the engineers tuned the 15-incher for tight bass while they tuned the 8-inchers for maximum output? Performance differences like these would make the results of a comparison meaningless."
So Butterworth decided to build his own 8-inch, 12-inch and 15-inch subs for the comparison test. He's designed and built his fair share of subs, so he has a lot of experience to draw on for making three subs that sound as similar as possible. All three designs used the same 200-watt power amplifier to drive the woofers. Butterworth knew he shouldn't be the one to judge his handiwork, so he enlisted three experienced listeners, who did not know at any given time how many and which subs they were listening to.
The "blind tests" eliminated any bias, and the panelists did not listen as a group. One by one they auditioned melodic bass lines from Steely Dan and James Taylor recordings, hyperactive kick drum and bass guitar workouts, subsonic organ notes from Saint-Saëns's "Symphony No. 3," and low-frequency bass from movies like "U-571," "King Kong," and "Star Wars, Episode II: Attack of the Clones."
The listeners all felt, literally, that the single 15-inch sub had the most feel-it-in-your-guts deep bass. That was pretty predictable, but the four 8-inch subs were favored for their better balance on movie soundtracks and pitch definition on music, compared to the two 12-inch subs or the single 15-inch sub. The four 8-inch subs had the most evenly distributed-through-the-room bass. The four 8-inch subs lacked the muscle of its bigger rivals; that's why the listeners were pretty enthusiastic about using two 12-inch subs. The 15-inch model was the "big bully" of the group, but lacked the definition of the smaller guys.
To get the full low-down on multiple subs, read Brent Butterworth's complete Sound and Vision magazine article.