Subwoofers are individual speaker units that are dedicated solely to reproducing low-frequency sounds. While this may not be the most glamorous job in a stereo or home theater system, the subwoofer can be a crucial part of your overall listening experience.

The typical frequency range of human hearing is between 20-20,000Hz. A subwoofer is responsible only for the very lowest end of this frequency range. The sub's low-pass crossover filters out all sounds above a certain frequency, and usually this crossover point is user-adjustable.

Low-frequency sound waves are very long, requiring large drivers and a lot of power to reproduce them faithfully. By assigning this difficult job to a dedicated unit (the subwoofer), you'll enjoy greatly improved bass performance.

Power and placement

One of the first things to consider when shopping for a subwoofer is how much power you need. If you have a large room (or if you just crave serious, room-shaking bass) then you should look for a sub with a more powerful built-in amp. Plus, as a general rule, the larger the driver, the deeper the bass — so go for a sub with a big 10" or 12" woofer cone (or a multi-woofer sub) for serious bass response.

Low-frequency sound waves are omnidirectional, so you have a great deal of flexibility when it comes to subwoofer placement. If you have a spot in your room picked out, consider the dimensions of the sub's cabinet to make sure it will fit. And if you are planning to place your subwoofer anywhere near your TV, be certain to get a video-shielded sub.

Down-firing and front-firing

Most subwoofers feature a single woofer cone that moves back and forth to create low-frequency sound waves. The woofer cone is usually mounted either on the bottom of the subwoofer cabinet (down-firing) or on one of the sides (front-firing). Neither method is intrinsically better — it all depends on the sub's specific design and on your own personal preferences.

Enclosures

"Enclosure" is another word for the cabinet that houses a speaker. By altering the design of the speaker cabinet, you can change the performance and output of a subwoofer. The two types of enclosures that we carry are bass reflex and acoustic suspension.

Acoustic suspension subwoofers use a sealed box to provide bass response. This method reproduces tight, accurate bass, but typically requires more amplifier power than a bass reflex design.

Bass reflex enclosures add a "tuned" port to increase and extend the bass response. The port is basically a hole in the cabinet that releases some of the energy created by the inward movement of the woofer cone. Bass reflex subs are more power-efficient than acoustic suspension models, but they sacrifice some accuracy in exchange for the added punch.

Who needs a subwoofer?

Most large floor-standing speakers deliver good bass response. Still, if you're using them in a home theater, or if you demand rich, full sound from your stereo music, plan on including a powered subwoofer for an added dose of deep bass content. Bookshelf speakers have a more difficult time reproducing lower frequencies and, in general, provide less bass response. For these speakers, the extra punch of a subwoofer is crucial.

Some satellite speaker systems available from Crutchfield include a subwoofer or bass module. These system components are engineered to match each other perfectly.