Face Off: Front and Center
Slowly but surely (and sadly, in many ways), we've become an overly centric society. Think about it for a minute: Companies (and entire industries, for that matter) are more centralized now than they've been since the days of the robber barons. And our government—let's not kid ourselves, friends: This ain't exactly Cold War Soviet Union, but it's not the sprawling, decentralized (and power-limited) federal structure that the Founding Fathers envisioned, either. Apparently, states' rights went out of fashion with the stagecoach and the stovepipe hat. Even from a cultural standpoint, our focus seems to have shifted dramatically toward the glorification of the individual over the good of the whole. But centralization certainly has its good points, as well (sure, it's an odd segue, but hopefully I got your attention). One need look no further than one's home theater system—that bountiful refuge from the madness of unchecked bureaucracies, hostile corporate takeovers, and me-me-me self-indulgence—to realize that a little centralization can go a long way in enhancing your movie-watching experience.
It almost goes without saying that any debate regarding the center-channel speaker in a multichannel system should be founded upon one basic tenet: When it comes to soundtrack reproduction, the center channel is the single most important speaker in your home theater. If you know a little about the way Dolby Digital, Pro Logic, and DTS soundtracks are mixed, it's easy to see why. Most people already know that the vast majority of dialogue is delivered from this channel in surround sound schemes. However, try unplugging your front and surround speakers sometime and listening to your center channel alone. You may be surprised by the amount of music, sound effects, and other soundtrack elements that emanate from this speaker. Proficiency with dialogue is just one qualification that a center channel must possess. Ultimately, this centerpiece of the system faces a complex cycle of reconciliation: How well can it juggle the diverse information being thrown its way, all the while keeping the critical dialogue…well…front and center?
While the importance of the center channel is defined by the information thrown its way in a soundtrack, its necessity is dictated (to a large extent) by the layout of most home theater environments. It's not often that you'll walk into someone's theater area and find a single seat. If home theater were a solitary activity, more systems could probably get by with one less speaker—after all, well-designed left/right speakers have a knack for creating a deceivingly centralized image. But movie-watching is usually a social event, involving at least two (and often more) viewers, all of whom want to hear dialogue coming from the same place that they are seeing the characters deliver it. With only two front speakers, the sound image begins to pull one way or the other as you move away from the sweet spot, which, in most systems, is limited to the dead center. With a center-channel speaker, on the other hand, dialogue and other elements that need to be anchored firmly to the visual image itself are done so with much greater accuracy for those in off-axis positions. The image is still more accurate for those parked in the center, but the window of effective and believable imaging grows considerably with the addition of a speaker in the middle. Of course, you don't want to simply plunk a center channel down in the middle of the front stage and consider yourself done. As with any speaker, placement has at least as much to do with your success as the quality and design of the speaker itself. From a general standpoint, the best positioning is directly above or directly below the video monitor or—for those using front-projection systems—right behind an acoustically transparent screen. A common mistake is to center the speaker on the top of the video monitor, which is correct from a left-to-right perspective but opens you up to problems from the front-to-back perspective. First reflections are a primary concern in any listening environment, and—when you leave a considerable gap of TV-top space between you and your center channel—you're going to get an early reflection off the top of the monitor that taints the image long before it ever gets to your ears. You still want to center the speaker, but place it as far to the front of your monitor as you can to avoid this problem. These days, most center channels are horizontally aligned—a design directive motivated more by placement conven-ience and feasibility than sonic benefit. Because of the nature of D'Appolito driver arrays (which many center channels are), some feel that a vertically aligned center channel represents a sonically superior displacement. Interestingly, this was a major directive of the original THX mandates, as well. That debate, however, will have to wait for another time.
Also an issue with this genre of speaker—and one that is central to our discussion today—is that of system matching. Can any center channel simply be added to a pair of left/right speakers for a successful front stage? There are, of course, varying opinions on this topic. Some argue that only speakers from the same manufacturer should be used across the front—and among that group, there are those who feel that all three speakers should be exactly the same. Others argue that, as long as you can achieve a blend that sounds good, what does it matter which speakers you use? My opinion? Speakers from the same manufacturer and, to a greater extent, speakers that are identical give you a much better chance of achieving a successful blend without a great deal of trial and error. This, however, doesn't at all mean that a great-sounding front stage can't consist of different speakers.
All speakers, even the best, alter the sound they output in some way. The glass-half-full type refers to this as timbre. Just like a musical instrument, each speaker has unique physical characteristics that determine the way it will reproduce sound. The glass-half-empty type refers to this as coloration. No speaker is 100 percent accurate, and they will all color (or change) the sound they receive in one way or another. Every aspect of a speaker's design and build has a sonic effect, whether it's cabinet construction, driver and crossover design, or the materials that are used throughout. The list goes on and on. This is why speakers that have more of these characteristics in common (e.g., speakers from the same manufacturer) have a better chance of blending successfully. Some systems are designed from the start to be 5.1-channel setups and thus, in theory, should make proper blending a top priority. There are no guarantees, however. Just because speakers are from the same manufacturer or were even designed to work together from the start doesn't mean you can assume anything until you listen to them, ideally, in your own room. On the flip side, mixing and matching brands and designs can certainly work, but it takes more effort and more listening on your part. Don't run out and buy a center channel because someone tells you it will blend well with your speakers. There are guidelines that can narrow your search but no shortcuts. The only way to be sure is to listen to the center channel in your room with your speakers. You can see where the logistics of this option can be daunting.
Because of the blending issue, we (myself, senior technical editor Mike Wood, and former audio editor Clint Walker) focused our attentions solely on the individual center channels in this Face Off by unplugging all of the other speakers in the room. Obviously, these center channels will never be used in this way, but using the rest of each manufacturer's system around the respective center channels would have taken attention away from the task at hand and turned this into a system Face Off, which we just tackled in the October 2000 issue. Using a reference set of front and surround speakers also would not have been accurate for our purposes, given that one of these center channels may have blended better with that particular set of reference speakers and therefore would have an unfair advantage over the rest of the field.
And a limited field it was. As always, I would like to thank NHT, Phase Technology, and Acoustic Research for having the cojones to step into our steel cage. While I probably didn't get to everyone who qualified under our somewhat-inexpensive-center-channels theme, I did get plenty of passes, which never ceases to disappoint me every time we do one of these things.
Isolated and running under the "small" setting (as they will in most systems, rolling off everything below 80 hertz) on our Lexicon MC-1 pre/pro, today's participants faced off with material from The Fifth Element, The Blues Brothers, and the DTS sampler disc (mainly the Sheryl Crow clip). In addition to the MC-1, we used the Sony DVP-C650D DVD player, Parasound HCA-1205A power amplifier, and Monster Cable speaker cable.