Music in the Round

What does this have to do with multichannel sound? Lots. First, if you have a source with a real center-channel signal, listening to it with a "phantom" center speaker (ie, none at all) means that the left and right speakers share that signal, and that anything that is different in the two sides will prevent those electrically divided signals from summing acoustically, to the detriment of the fidelity in that center signal. In fact, it is a theoretical impossibility that the two main speakers, despite Herculean efforts in placement, room treatment, and even DSP, can be equally represented in the listener's two ears. Wait a minute, you say. How come my stereo does such a great job with two speakers? Well, it can do so only because the recording engineers and the mixing and mastering teams have tweaked and balanced all the sounds to optimize your chances of getting a solid (stereo) presentation, and because you use matched speakers and good room setup.

But try this: Find a good monophonic recording—a real one, not something mixed down from multimiking or a stereo master. Even a recording from the era of acoustic recording (ie, before 1926) that has been transcribed to LP or CD will do, because it is not overall frequency range or resolution but imaging that is at issue here. Compare how a mono voice or instrument sounds through two speakers with how it sounds through one, taking into account with the volume control that it will be 6dB louder through two. I'll bet you a doughnut that the voice sounds more coherent, more integrated, more human through the single speaker. Two speakers will sound louder and more spacious, but not as real. So if you're listening to multichannel recordings with a center channel, you need a center-channel speaker—once you split the signal electrically, you can't put it together again acoustically.

A corollary is that the center-channel speaker must be identical in timbre and dispersion to the other two front speakers or, again, any common signals will be compromised and sounds that move across the stage, as in live opera recordings, will change in character with position. For me, this disqualifies almost every horizontal two-way center-channel speaker on the market, especially those ubiquitous midrange-tweeter-midrange designs (though they work nicely when stood on end). The solution lies in choosing a three-way center-channel speaker whose midrange and tweeter are stacked vertically. These range from B&W's elegant HTM-1D, in which a full-size Nautilus midrange-tweeter assembly sits atop a horizontal array of woofers (spaced closer than one wavelength in their range), to the very clever Phase Technology PC-3.1 II, with its rotatable midrange-tweeter module. Unfortunately, these tend to be the larger designs in most lines, and probably won't appeal to those who set their video priorities ahead of their audio obsessions. For sound quality, however, it matters, and my seemingly minor change of center-channel speakers proved it.

Putting my money where my mouth is
In the two years I've been writing this column, I've reported on my experiences in the weekend system even as my listening habits became increasingly bipolar: multichannel in the country on weekends, stereo in the city during the week, as I schlepped a tote-bag full of SACDs and DVD-Audio discs back and forth. Although the overall quality, range, and power of the main stereo system remains superior, I missed the frisson I got from classic three-channel SACDs and other multichannel recordings played in two-channel through the big system. No way out: I made the big commitment to go multichannel in Manhattan.

Because I had no intention of discarding my Revel Ultima Studios, which enjoy a symbiotic relationship with my city listening room, and did not want to sacrifice a whit of that system's current two-channel performance, any multichannel system would have to be built around the Ultima Studios. I spent a lot of time listening to the Revel Voice, a really impressive center-channel that not only meets the criteria discussed above but incorporates adjustments for boundary proximity. The Voice is a decidedly full-range speaker that I've enjoyed as the centerpiece of my daughter's HT system, but it wasn't for me. For one thing, I have no video monitor above or below which the Voice had to fit. For another, the Voice's large horizontal shape, even in a matching finish, would be quite different in appearance from the flanking Studios. Besides, what could possibly be a better match for the Studios than another Studio?

But because Revel Ultima Studios are sold only in pairs (how's that for pushing the dedicated center principle?), it took some time to locate and buy a single matching unit. Plopping the newbie down in the room meant that I had to begin anew the entire process of speaker placement, one I'd thought was long behind me. The left and right speakers needed greater spacing to open the soundstage, but that put the left speaker too close to the sidewall, at the end of a large piece of wooden furniture. The result was a bass hot spot in that corner, and reflections of the speaker's output from the hard surfaces, which put that side of the room out of balance with the other.

I've used pairs of Echo Busters for some years to assist with reviewing speakers, but I knew they were not, by themselves, up to this task. However, a pair of Echo Buster Phase 4 towers were just the ticket. These 12" by 12" by 48" columns have four sides—two perforated, two solid—and are filled with foam. When I first obtained them, I tried them in the room corners behind the speakers but they soaked up too much bass, leaving the sound too lean. This time I placed them on the sidewalls, their perforated sides facing the main speakers. This tamed the bass hot spot without sucking the life out of the room, and mitigated those pesky short reflections, which impaired lateral imaging. It also left enough space to center the new Ultima Studio precisely between but slightly behind the others, to maintain the three front speakers' equidistance from the listening chair. The front of the room was good to go.

The surrounds remain a work in progress. Because the room is L-shaped, the surrounds can go back only as far as the shorter sidewall, which places them directly lateral to the main listening position. I got good results from Meridian DSP5000s in those positions, but that model has all sorts of adjustments for amplitude, delay, and boundary compensation; all I've got now is amplitude (and, with some sources, delay). For the time being, the rear channels are Paradigm Studio/20s on stands at ear level, and I do my serious multichannel listening on temporary seating in the middle of the room.

Finally, new electronics. Having made so many changes in my system, I figured the quickest route to gratification would be with the familiar Bel Canto amps and the PRe6 multichannel preamp (see the December 2003 "Music in the Round"). I ran the Ultima Studios with an eVo6 by bridging its six channels to three and boosting its output to +300Wpc. An eVo4 was similarly bridged to run the Paradigm Studio/20s, and although such power certainly isn't needed for these speakers, all my experience with the eVo amps says that they sound even better bridged than separate. Finally, I installed a PRe6 configured with stereo inputs for my essential FM tuner and the balanced outputs of the Theta Gen.VIII D/A processor, as well as both the stereo and multichannel outputs of the Sony XA-777ES SACD player and Bel Canto's PL-1A universal disc player (review in the works). This setup lets me select either of the players via their stereo outputs, their multichannel outputs, or their digital outputs via the Gen.VIII. The Bel Canto PRe6 is one heck of a capable preamp!

How does the system sound now? In a word, glorious. Having enjoyed the Bel Canto amps and preamp in the more modest weekend system, and having found them more honest and enjoyable than any other combination, I was anxious to see if they could work their magic in a more challenging application. They do. They've retained their strengths and personalities and are appropriate partners for the best speakers and sources. Their strength is a remarkable lack of glare or highlighting that is consistent regardless of power levels. The eVo power amps hum briefly when powered up but are dead silent within seconds and remain so. Also, they remain barely warm to the touch, more affected by the sunlight falling on their black cases than by any extreme power demands. The PRe6 is a delight to use, even in this complex system, and seems entirely devoid of noise or any switching or control artifacts. Running the output from the Gen.VIII directly to the amps or via the PRe6, the proverbial bypass test, I could hear no differences at all. Compared to the McCormack MAP-1 preamplifier, the PRe6 is more complex to use but more flexible, less bright, and more quiet, neutral, and transparent. The PRe6 is as good a stereo preamp as it is a multichannel control center.

Did I say the Bel Cantos had a personality? Well, yes, but I think of them as characteristically nonaggressive—they might sound less brilliant or even unexciting in a direct A/B comparison with more flashy-sounding components. But that's good. In fact, in multichannel, where music and ambience are conveyed from the source to the ears by the system, the self-effacing Bel Canto amps get out of the way and let the program communicate without imposing anything on it.

I compared the bridged eVo6 with the Classé Omicrons that I reviewed in November 2004. The power and richness of the Classé brutes were perfect for two channels but, because I didn't have five of them on hand, I can't comment on how they might conspire in multichannel. They seemed a bit too robust to mate with the eVos on the other channels. The bridged eVo6, on the other hand, sounded better and better in stereo the more I ran it, and sounded equally neutral with the Ultima Studios and with the new B&W N802Ds (review underway). Available power might be less than from the Omicron, but it was more than I could reasonably use with either speaker.

Most of the above comments about the marvelous spaciousness and immediacy of the Mercury Living Presence SACDs is from listening to them through this evolving system. They were great up in the country, but the three Ultima Studios and the Bel Canto electronics revealed how much more is encoded in these tracks. With more modern recordings, such as those reviewed in the accompanying sidebar, "Recordings in the Round," the contrast is even more marked. I guess that's nothing new around here: Better equipment and better acoustics do make a difference, regardless of the number of channels. Now, how to slip another pair of Revel Ultima Studios past my wife...