Home Theatre Speakers - What You Need To Know

By: Microtek Lab Inc

•Speaker types

There are four basic home theater speaker categories: towers, satellites, subwoofers, and center channels. A tower speaker is a tall, freestanding model capable of reproducing a full range of sound. Satellites, which can be used as both front or rear-channel (surround) speakers, are small, bass-limited models designed to be paired with a subwoofer - a dedicated speaker for reproducing both bass and the low-frequency-effects channel in Dolby Digital and DTS soundtracks. And a center channel speaker is a horizontally oriented satellite that's designed to reproduce dialog.

•Freestanding vs. on-wall

In the past, home theater speakers were usually installed alongside big-screen TVs - either freestanding or placed on top of speaker stands. But many new models are on-wall designs that come with wall-mounting hardware. One advantage to these kinds of speakers is that they get positioned on walls where they don't take up any room space. A second advantage is that their slim, wall –hugging design nicely complements flat-panel plasma and LCD TVs.

•Do you really need a center channel?

With some systems - especially those built around a large, slim rear-projection TV - finding a place to put the center channel speaker can be a problem. Although you can get by without using one, it's not recommended - center channel speakers are specifically designed to reproduce voices. You'll find that movie dialog will sound much clearer when you use them. So instead of bypassing the center speaker or using the TV's built-in speakers as a center channel substitute (a terrible option, since the tonal balance of your TV's speakers isn't likely to match that of your other speakers), look for an alternative mounting method. Speaker wall mounts make a fine option, especially with flat-panel TVs. Most TV stands also include storage shelves that can hold a small center channel speaker.

•Speaker connections. A variety of connectors can be found on the back of speakers.

•A spring-clip connector is a plastic, spring-loaded clamp that's usually found on the back of inexpensive speakers. The connection provided by spring clips isn't as secure as other types, and they can only accept bare speaker wire.

•Binding posts are a step-up connection option found on high-quality speakers. There are two types of binding posts: regular and five-way. Regular types accept both banana plug and spade-lug connectors on speaker cables. The connection they provide is very secure, and in some cases the connector is also gold-plated to prevent oxidation - a condition that can potentially degrade performance. And five-way binding posts, which accept bare wire and pin-type connectors in addition to banana plugs and spade lugs, offer even more hookup flexibility than regular types.

•In-wall and in-ceiling speaker + and –

For those who prefer to keep their audio/video equipment out of sight, in-wall and in-ceiling speakers make a great alternative to regular models. Although the sound quality of in-wall and in-ceiling models is generally a notch below that of regular speakers, they can be mounted inside of cutout cavities in the walls or ceiling of your room where they won't take up any space. Both types are also designed to contain vibrations within the cabinet, so you won't have to worry about rattling the walls during action movies. Installation of in-wall and in-ceiling speakers involves running wires through the walls and/or ceiling of your home. If you're an experienced DIY type, you might be up to that task, but for most people it's best left to a custom installer.

•Surround speaker considerations: direct-radiating, dipolar, and bipolar There are several options to consider when choosing surround sound speakers for your system.

•Direct-radiating models fire sound directly out from the speaker's front baffle toward the listener's ears. These are a good all-purpose surround sound speaker choice since their clear, focused dispersion pattern can accurately convey the directional sound effect pans in DVD soundtracks.

•Dipolar models radiate sound from both the speaker's back and front, with the opposing driver sets wired out-of-phase with each other. This design offers a more diffuse, spacious sound than a direct-radiating model while retaining some of the latter's focused dispersion characteristics. (Dipolar models are favored for THX-certified designs specifically because of their diffuse sound, which more accurately resembles what you'd hear in a real movie theater.)

•Bipolar models also radiate sound from the front and back, except that in this case both sets of drivers are wired in-phase with one another. This design allows a bipolar speaker to provide the best of both worlds: a direct-radiator's clarity and focus, and a dipole's spaciousness.

•What is frequency response, and what should I look for?

The range of audio frequencies that a speaker can reproduce is known as its frequency response. Human hearing extends from 20 Hz to 20 kHz (20,000 Hz) - a span that few models are able to cover fully. The bass frequencies at the bottom of the range (approximately 20-120 Hz) are the most difficult for a speaker to cover. Satellites don't attempt it at all, but instead pass the task off to a subwoofer - a dedicated bass speaker with drivers large enough to move the massive quantity of air needed to reproduce low frequencies. Since tower speakers usually contain one or more woofers, they generally deliver decent bass. But if you're shopping for tower speakers - especially if you plan to use one in a system where there's no subwoofer - make a point of checking the low end of its frequency response specification. And remember that not all measurements are the same. For example, the bass response of a speaker spec'd at –6 dB at 40 Hz probably won't sound as full as one that measures –3 dB at 40 Hz.

•Speaker impedance and selection

Most new speakers are designed to be compatible with a wide range of receivers and audio amplifiers, so specifications like impedance-the measure of a speaker's resistance to electrical power flowing through it as specified in Ohms-generally aren't things you need to worry too much about. But what you should know is that an amplifier has to work harder to drive a speaker with a lower impedance rating than one with a higher rating. Say that your receiver is rated to deliver 100 watts into an 8-ohm load. If your speakers have an 8-Ohm impedance spec, then you aren't likely to encounter any problems. But if your speakers' specified impedance is 4 ohms or less, the chances for that same receiver to overheat and shut down will be increased.

•Placement: the final frontier

Many people tend to be casual about where they put their speakers; more often than not, they get shoved into any old space where it's convenient. But speaker placement becomes crucial when setting up a home theater system. You'll want the positioning of surround sound effects in your room to correspond to what's happening on screen, and that will only happen if speakers are set up properly.

Front channel towers or satellite models on stands should ideally be placed equidistant from the TV's sides and about three feet out from the front wall. This setup will heighten imaging and reduce any sound-muddying room reinforcement effects. And your subwoofer should be pushed into a corner of the room to permit the sound-reinforcing effect of adjacent walls to strengthen the bass. While placement guidelines for surround speakers are less strict than those for front speakers, installing them in a high position at the sides and slightly behind the listening area will usually enhance surround sound envelopment.

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