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Home theater subwoofers guide

How to choose the right size and power level

Klipsch SW-112 Powered subwoofer

A subwoofer is essential for deep, dramatic bass. (Klipsch SW-112 pictured)

The rumble of an explosion, a crash of thunder, the boom of a drum — some of the most exciting audio effects in home theater are produced by a powered subwoofer. Subwoofers are individual speaker units that are dedicated solely to reproducing low-frequency sounds, making them a crucial part of your overall listening experience.

Who needs a subwoofer?

The typical frequency range of human hearing is between 20-20,000Hz. A good home theater system should be able to reproduce most of the frequencies within this range. Since front and center channel speakers tend to have trouble reproducing the lowest frequencies, a subwoofer is necessary for filling in the very lowest end of this frequency range.

Bear in mind that 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 those heart-pounding thumps and deep, rumbling roars that make Hollywood blockbusters so thrilling.

If you enjoy listening to music in a two-speaker (stereo) setup, then large floor-standing speakers can deliver good bass response. Still, if you're also using them in a home theater, plan on including a powered subwoofer for an added dose of deep bass. Also, keep in mind that 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.

What to consider when looking for a sub

There are a wide variety of subs out there. To help you pick one, keep these things in mind as you shop:

Power and size

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.

Down-firing or 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.

Placement

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. For more tips, check out our article or our video on speaker placement for home theater.

Enclosure type

"Enclosure" is another word for the cabinet that houses a speaker. The design of the enclosure can change the performance and output of a subwoofer. Two of the most common types 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 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.

Convenient extras to look for

All subwoofers perform the same basic function — they reproduce the lowest frequencies in a home theater setup. But some subs also include features that boost performance or make them easier to use.

No room for a sub?

No problem — compact or ultra-compact subs are designed to deliver great bass while being as unobtrusive as possible. Some subs are even designed to be placed on or inside your living room furniture, and some furniture pieces actually come with subwoofers built into them. And if you don't mind the installation, then an in-wall subwoofer can be a great option. It uses the space behind your wall or ceiling as a giant cabinet, producing deep, powerful bass without taking up any floor space.

Polk Audio PSW111 Ultra-compact powered subwoofer

Many ultra-compact subwoofers take up less than a square foot of floor space, making them small enough to hide under an end table or in a corner. (Polk Audio PSW111 pictured)

Want the best bass with everything?

Check out subs with preset modes — they customize the sub's bass response depending on what you're listening to (Movie, Video Game, Rock Music, Jazz Music, Sports, or Night Listening). Many subs also have some form of built-in equalization to help you customize the sub to the acoustics of your particular listening space. Some subs simply allow you to indicate your sub's placement (corner, mid-wall, in-cabinet, etc.), while higher-end subs may actually take sound samples using an included microphone and automatically tailor the sound to suit your room.

Don't feel like messing with hard-to-reach controls?

To help you manage all your sub's features, look for one that includes a wireless remote control. You'll really appreciate the convenience of not having to get up to adjust the subwoofer's volume knob on the back of the sub every evening when your spouse or children go to bed.

Want the convenience of a wireless connection?

Even if you're willing to place your sub far from your receiver, you might not want a long wire running between the two. No worries. A number of subwoofers include the ability to connect wirelessly to your system. Some models feature a built-in (or optional plug-in) wireless adapter that receives audio signals from a separate transmitter plugged into your home receiver's sub output. Others come complete with all the adapters you need for a wireless hookup right out of the box. There are even wireless adapter kits that let you transform virtually any sub into a wireless sub so you can feel those deep rumbling movie sound effects without tripping over a cable when you get up to get more popcorn.

Once you've chosen your sub, check out our tips for getting your subwoofer connected and fine-tuning your bass.

Consider adding a second subwoofer to add balance and impact

Low frequency sound waves are very long. As these waves reflect against the walls in your room, they return toward the subwoofer and can overlap with the original sound wave. In some spots, the waves will cancel each other out, creating a "node" or "null point." This means some areas of your room will have significantly weakened bass response compared to others.

dual subwoofer diagram

In the diagram above, the orange lines represent the original sound waves and the blue lines represent the reflected ones. Where they meet are the nodes, shown by the red "x."

Adding a second subwoofer can fill in those gaps where bass response is weak. This helps make every seat in your home theater a good one, with plenty of tight, deep bass.

If you'd be interested in using two subwoofers in your home theater system, consider a home theater receiver with dual subwoofer outputs. This feature is fairly common these days, but not with older receiver models.

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