Bass Bruiser

Monolith by Monoprice 13-inch THX Ultra Certified subwoofer

- By Daniel Kumin

GOT BASS? I do. Boy, do I ever: Monolith by Monoprice's newest THX Ultra Certified 13-inch behemoth. You might think that a 13-inch sub would be just a bit bigger than a typical 12-inch job, maybe 15 or 16 inches wide, and perhaps as heavy as 70 or 80 pounds. Think again.

The 13THX (what I'm calling it since Monolith's sub does not appear to have a name per se) is roughly 20 x 24 x 29 inches (WxHxD) and tips the scales at a svelte 153.2 pounds. And that's the little one. There's also a companion 16THX-yes, with a 16-inch driver-that weighs 176 pounds. The new THX Certified subs, like the rest of the Monolith line of subwoofers, speakers, and components, comes from Monoprice, the direct-marketer that started out with cable and computer accessories but has grown into a giant seller of all things audio and much more.

Subwoofers, like all loudspeakers, are in effect pumps: they don't move air very far, but move it they must in order to induce the airborne vibrations that we hear as sound. The lower the frequency the more the work involved, and much as with piston engines (another sort of pump) there are few substitutes for cubic inches. (Few, but not none: equalization, amplifier power, and extreme driver throw can in combination do the trick, up to a point.)

A bigger diaphragm interfaces with more air molecules, and thus has a huge advantage in efficiency, in the physics sense, over a smaller one. (This should not be confused with loudspeaker sensitivity, even though the two terms are often bandied about interchangeably.) A 13-inch circle has 15 percent more area than a 12-inch one, which suggests why Monoprice bumped its newest Monolith sub up that one mere inch.