The Basics: Home Audio Speakers
Seemingly overnight, your stereo system became obsolete. How did it happen? Simple--DVD technology took over the VHS home movie kingdom, and suddenly, stereo was "out" as surround sound became an easily attainable home theater option.
You could easily purchase all the speakers you would need to achieve what has become the minimum requirements for home theater: front left and right speakers, a center-channel speaker, a pair of surrounds, and a subwoofer. You can match up individual pieces to create yourown system. Just make sure the piecies: work well together; are timbre matched; and that you have enough cable to hook them up. Or, you can simply purchase a complete system, with all those concerns already taken care of.
At the same time, there is still a place for stereo speakers. A vast majority of music purchased today is stereo (two-channel) in nature, and robust stereo speakers will provide much better audio reproduction than the front left and right speakers of a home theater system. In addition, a pair of stereo towers can serve admirably in a multichannel home theater system. They might not be a perfect tonal match with the other speakers in the setup, but the difference will not be audible to most listeners.
If there's one technology that has remained fairly unchanged for many years, it would have to be speaker design. Basically, a magnetic voice coil moves a diaphragm to generate audible frequencies--that's all there is to a speaker. What has changed is the precision with which they're built, the choice of materials used and the shape of the cabinets that house them.
For years, subwoofers were reserved for car audio fanatics and a few audiophiles. With the recent explosion of home theaters, subwoofers are taking their rightful place...hidden on the floor in the corner of the room. The ".1" in 5.1 refers to the LFE (low-frequency effects or low-frequency extension) track that allows sound mixers to put an incredible amount of bass into a movie soundtrack--both musically and with sound effects. Most speakers don't have the frequency response to handle these extremely low frequencies, so a separate subwoofer, specifically designed to reproduce these sounds, makes sense.
The human ear has a hard time localizing low bass frequencies, particularly sounds that are less than 120Hz. The phenomena allows placement of subwoofers wherever they might sound and look best; fortunately, the corner of a room usually satisfies both criteria.
These days, most subwoofers are powered, or "active," meaning they come with a built-in amplifier that needs to be plugged in, so plan accordingly when figuring out where you'll place it. The size and power can range from a small 8-inch driver with a modest 50-watt amplifier to dual 15-inch speakers with over 1,000 watts of power. You can get as much bass as your home's foundation can handle.
How to Shop
Home theater speaker systems are typically complete packages of five speakers and a subwoofer, although some do not include a subwoofer. These speakers are the proper configuration you need to reproduce 5.1 surround sound; the "5" refers to the front left, front right, center, and two surround speakers, while the ".1" refers to the subwoofer channel. Some systems even include color-coded cables, making setting up the speakers a snap.
These sets come in a huge variety of sizes, styles and power ratings, so you need to determine what your listening requirements are. A system that uses large speakers all around will probably also sound good for music listening; a system comprised of small satellite speakers and a large subwoofer will work fine for most movies, but it might not be as satisfying reproducing a full-range piece of music. A nice compromise might be a system with large front left and right speakers and smaller satellites for the center and rear speakers--this covers you more than adequately for music, and it still has the full speaker compliment required for 5.1 movie magic.
Home theater speaker systems are different from what are known as home-theaters-in-a-box, or home theater systems. When you purchase a home theater speaker system, you'll still need a TV, a DVD player and a receiver or amplifier with six channels of amplification, with either the DVD player or receiver handling the surround sound decoding process.
Stereo speakers come in a huge variety of shapes and sizes--from the tiniest "jewel-cube" style and compact multimedia speakers that flank most computers, to neat bookshelf monitors, to floor-standing behemoth towers that take a few people to move. In this category, typically, size does matter. Basic physics limits the lower frequency limit that a speaker can produce. Tiny drivers physically cannot produce a distortion-free low bass note at a decent listening level. Many times, this is overcome by adding a subwoofer that can be hidden out of sight in cases where style must rule over functionality.
Speakers are one situation where it is absolutely essential for you to personally audition your purchasing options. The sonic differences between speakers that look to be about the same size, even ones with similar looking frequency responses, are huge. Bring a few selections of your music and movies with you and listen to the differences between speakers. One speaker that artificially enhances certain frequencies might sound good on one piece of music and terrible on another. One system might rock on movies but turn your music into mush. Check that your amplifier has enough power for the speakers.
Make sure that you like what you hear, but also take into account the size of your listening room. Huge speakers that would never be fully powered because your listening room is small would sound very different than they sounded in a large store. Alternatively, small speakers that sounded good in a small room at a retailer might sound weak and thin if you've got a large acoustic space to fill. Make your purchase from a store with a good return policy--be certain that you can return your selection in a reasonable time period for the simple reason that it does not sound good in your home.