The Basics

If you have ever wondered what it is that makes going to a movie theater such a great experience (besides the huge screen), it is in large part due to the giant soundstage created by the speaker system. One of the most important parts of that system is the powerful subwoofers that make the room shake and rumble. With the advent of digital surround receivers, you can recreate this cinematic experience in your home by purchasing a full set of speakers for your home theater; however, if you haven't added a powered subwoofer to your system, you are missing out on one of the most exciting parts of the home theater experience.

One of the most dramatic improvements you can make to a home theater setup is the addition of a powered subwoofer. Adding a subwoofer creates a level of realism in your movies and music that traditional speakers are not capable of producing on their own. Explosions, gunshots and punches will have an impact that you can actually feel. The throaty roar of an engine will have you swearing you can smell the exhaust, and the rich texture of a cello in a string quartet will send tingles down your spine. Although you can hear these sounds on floorstanding and bookshelf speakers, they cannot produce the subsonic frequencies necessary to "feel" the action.

This is where a subwoofer comes in. A quality subwoofer picks up where your other speakers reach their limits for low frequencies. Speaker systems that combine small satellite speakers with a subwoofer are very common today, and represent an entry level for small subwoofer-based speaker systems. Quite often, the subwoofer module included with these systems will be about the size of a tower PC, and will house not only the woofer but the amplifiers and crossover network for the satellite speakers. Generally, the subwoofers included in these systems are built to round out the sound of the satellite speakers rather than create the tactile impact you get in a movie theater. If you have a set of bookshelf or larger full-range speakers, you will want to consider adding a powered subwoofer

Stand-alone, powered subwoofers range from small cubes to large water-heater sized cabinets that can literally shake the walls of your home. They typically have a built-in, high-powered amplifier dedicated to driving a powerful woofer that creates the tactile bass you've experienced when at the movies. These subwoofers generally have a line level, RCA-type input that receives LFE (low frequency effect) signals imbedded in Dolby Digital and DTS soundtracks from DVD's and high-definition broadcasts. They often have an adjustable crossover on the rear control panel that will choose which frequencies are to be reproduced by the subwoofer, and which will be handled by your speakers. There will usually be a level control as well, allowing you adjust the output.

Many of today's digital a/v receivers have advanced bass management that sets the crossover point via the receiver, rather than on the subwoofer itself. Using this type of setup, we recommend you connect the subwoofer to the "sub out" jack on your receiver, and then connect your speakers to the appropriate speaker outputs on the receiver. Using the speaker setup menu in your receiver, set the "bass out" to "LFE," and experiment with choosing "large" or "small" for the other speaker settings. Adjust the volume level on the subwoofer and find the right blend of sound for your room.

Placement within your room is a very important part of optimizing the performance of a subwoofer. You should consider not only what location in the room will provide optimum sound, but also take advantage of the ergonomics of the room as best you can. Placing a subwoofer in a corner of the room will generally allow the bass amplitude to reach its maximum potential, as it will have many surfaces to couple with. But this will not always be the best choice, as it might create too much bass. Every room is different, and taking the time to try different locations for your subwoofer will pay great dividends in producing the best sound possible for your listening position.

Five Questions Before You Buy

1) Does your receiver have a LFE output?
If you have an older receiver without digital surround outputs, you might want to consider a satellite/subwoofer speaker system. Purchasing an expensive powered subwoofer for an outdated receiver will not likely produce the results you are looking for. If you have purchased an expensive new digital a/v receiver and a fancy set of floorstanding speakers with dipole surrounds for the rear of your room, you should strongly consider a quality powered subwoofer that will complete what will be a very impressive home theater system.

2) What is your budget?
As is always the case, budget should be considered when shopping for subwoofers, just as with any other piece of gear for your home theater system. You can often find holiday specials on respectable powered subwoofers for as low as $99 that would work well in a modest system. The price of larger, more powerful subs can easily climb into the thousands if you have a high-end system. Some companies specialize in subwoofers, while most speaker manufacturers offer subs built to compliment their own product lines. It is not necessary to buy the same brand subwoofer as your speakers.

3) Big or small?
Surprisingly enough, size does not always equate to power when it comes to subwoofers. Modern engineering has allowed incredibly high powered amplifiers to fit into tiny enclosures housing woofers--as small as 8 inches in diameter--with room shaking results. These powerful subs can be a good choice for a small to medium sized room. If you have a dedicated room that can handle a large subwoofer cabinet, there are square or rectangular enclosures housing 16- and 18-inch woofers. There are even subwoofers that resemble hot water heaters, tube shaped enclosures designed to stand upright in the corners of large rooms.

4) Music or movies?
Most powered subwoofers will make a huge impact on your movie experience. But often times tuning a subwoofer to sound good with music is more challenging. If you are a music buff and will be using your system for music as much or more than movies, be sure to look for subs that have been designed with music in mind.

5) How close are your neighbors?
If you live in an apartment building, you should think twice about purchasing a powerful subwoofer. It will literally shake the walls of the room it is in, and your neighbor under you, or adjacent to you will not necessarily appreciate the disturbance even at moderate volume levels. Does your baby sleep in the room above or next to your home theater? If so, you might have issues after adding a subwoofer to the equation.

How To Shop

Subwoofers are now widely available not only at specialty hi-fi stores, but at big box and internet retailers as well. Be sure to understand how a subwoofer will connect to your system so you know what type or design will be appropriate for your situation.

Very good quality subwoofers can be found in large electronic retailers, often on sale in weekend newspaper flyers. This is a great way to add dramatic impact to your existing system on a tight budget.

Be sure to consider what the options are in your room for placement of a subwoofer, and how large the sub can be before you bring anything home. It is always important to look for a retailer, whether it be an internet-direct manufacturer or a brick-and-mortar store, who has a generous return policy in case the subwoofer you purchase is not a good fit for your room or system.

When you get home with your subwoofer, experiment with different positions for placement in your room, and use music and movies that you are familiar with as you find the best location. Taking time to set up your receiver's speaker settings and finding the proper adjustment of the level and crossover of your sub will reward you with cinema-quality sound in your home.