Turn It Up!

Loudspeakers come in a variety of sizes, from floorstanding, to stand-mount monitors, to smaller satellites, and, of course, subwoofers. Some can go on walls or (better yet, both sonically and otherwise) in walls. (See the separate section regarding in-wall speakers.) Most speakers consist of at least two drivers, a woofer and a tweeter, with crossover circuitry between them routing the correct frequencies to each driver. These are two-way designs; add a midrange driver and another crossover, and that’s a three-way speaker.

The most common home theater speaker array is a 5.1-channel configuration with a front pair, a center channel, a surround pair, and a subwoofer. There are 6.1-channel sets, which add a single rear surround speaker (with the regular surrounds serving as side surrounds). 7.1-channel sets have become increasingly popular—they have two rear surrounds.

The front speakers are usually the largest in the system. You can use smaller satellite speakers in front, but they don’t provide the same impact as a large, floorstanding speaker. A few front speakers are powered towers, which include an internally powered subwoofer section. This eliminates the need for an external subwoofer, potentially saving both space and money. With powered towers, however, placement and upgrade options for the subwoofer are naturally restricted. You can’t assume that the best location for your front speaker is also the proper location for your sub—in fact, it usually isn’t. Anyway, powered towers have become increasingly rare, because the side of a speaker is not necessarily the best place for a subwoofer.

One desirable feature to have in an in-wall speaker is a pivoting tweeter. This allows you to direct the high frequencies toward the listening position or wherever else you want. A pivoting tweeter is no substitute for getting the placement right—and only an experienced custom installer can do that—but it does give you more options.

The center channel is crucial, given that this channel reproduces virtually all of a soundtrack’s dialogue and far more music and effects than people think. Any fullrange (or close-to-full-range) speaker can potentially make an effective center channel, but the most common design is one with direct-radiating drivers in a horizontally aligned cabinet, which makes placement above or below a television or movie screen easier. Try to find a center channel that is as well matched—both physically and sonically—to your front speakers as possible. A good pairing of the center and fronts will minimize timbre-matching problems and other performance issues that can undermine your front soundstage’s cohesiveness. Using speakers from the same manufacturer doesn’t guarantee a good timbre match, but it’s certainly the best place to start. Far and away, the best option is to use identical speakers across all three front channels, even if that means going with smaller speakers. Let the sub(s) do the heavy lifting of bass frequencies.

The most common surround speaker designs are either direct radiators that use a single set of drivers (monopolar) or those that use two separate baffles and driver sets. There are two important types of dualbaffle designs: bipolar speakers, where the driver sets operate in phase, and dipolar speakers, where the driver sets operate out of phase. Monopole and bipole models offer more direct sound and tend to be better for surround music, whereas dipolar models offer a more diffuse soundfield and are harder to localize, which makes them better for movie soundtracks. THX mandates dipolar surrounds for a THX-certified system. Some dual-baffle models offer switchable dipolar and bipolar radiation patterns.

Driver sizes, in the age of the subwoofer, don’t matter as much as they used to. Most home theater systems have woofers of 3.5 to 6 inches, with the sub handling most of the bass reproduction. Driver materials, however, can affect sound—especially in the tweeter—so pay attention to the specific character of silk domes, soft (plastic) domes, metal (titanium or aluminum) drivers, and drivers made of various composites. Also note the way the tweeter is built into the speaker. A waveguide may prevent sound from bouncing off walls, and that can be helpful acoustically, but it can also limit dispersion, making the sound better at some listening positions than at others.

When it comes to finding the right speakers, there’s no substitute for listening in your own room—paying particular attention to the cohesion between the room and the speakers and between the amp(s) and the speakers. Measurements, advice from others who have experience with the same products, and simple logic about which room and amplifier characteristics would match well with which speakers will help to a large degree. But your ears should ultimately be your guide.

Remember that a room has a far greater impact on a system’s sound than anything else. A system that sounds spectacular in one room can sound mediocre or even subpar in the room next door.There’s a lot you can do to change a room’s sound, but try to be fully aware of how these changes will affect the sound right from the start. Be careful about trying to compensate for deficiencies in one element of your system with another. If you’re looking for a flatter response, find speakers and amplifiers that are flatter to begin with, rather than trying concoctions like mixing aggressive speakers with mellow amps.

Two important criteria to consider when matching your speakers to an amplifier are sensitivity and impedance. Sensitivity tells you how much sound pressure (measured in decibels) a speaker outputs when fed a certain amount of power (usually 1 watt), measured from a certain distance (usually 1 meter). The more sensitive the speaker is, the easier it is to drive. For example, it takes twice as much amplifier power to drive an 87-dB-sensitive speaker as it does a 90-dBsensitive speaker to achieve the same volume level. Room efficiency is sensitivity plus a few decibels to account for room interaction; therefore, room-efficiency specs tend to be higher. Impedance is a measurement (in ohms) of the electrical resistance that a speaker presents to the amplifier. Speakers with lower impedance present a more difficult load to the amplifier. Lower impedance (4 ohms and below) and lower sensitivity can be a particular problem for many receivers and other current-challenged amplifiers. Speakers in lower price ranges tend to be more sensitive and have higher impedance. Even though impedance varies with frequency, most speakers that you’re likely to pair with a receiver or an inexpensive amplifier shouldn’t dip into amp-compromising resistances.

Speaker terminals should be binding posts that screw down onto the bare wire tip or interlock with cables terminated in spade lugs or banana plugs. Cheaper speakers have spring-loaded wire clips. While it is easy to shove a bare wire tip into a wire clip, the connection is not very secure, and the area of surface contact is not as large as it would be with a binding post. Avoid speakers with wire clips, except maybe for cost-sensitive background applications (in other words, when you just couldn’t care less about sound quality). Keep them out of your main system.

Some speakers have dual sets of binding posts to allow for biwiring or biamping. Biwiring uses a Y-cable with two tips at the speaker end and one at the amp end. This allows each driver in the speaker its own path to the amp, preventing the woofer’s low-frequency demands from sucking power away from the tweeter and collapsing the soundstage. Biamping, which provides each of the dual terminals with a separate amp channel, is better yet—and it can provide greatly enhanced dynamics if done right. It is most suitable for an extremely high-end system in a large room.