Bookshelf Speaker Reviews

Price: $1,307 At A Glance: Horn-loaded tweeter draws on long Klipsch tradition • Tweeter surround allows more piston-like movement • High sensitivity suits any A/V receiver

Toot Your Horn

Surround sound is an indispensable part of home theater. But some people still have difficulty making the leap from two-channel to 5.1-channel-plus. One question that comes up is: Doesn’t going from two speakers to five or more place a strain on the amplifier? After all, an amp driven into clipping suffers from harshness and compression, and that’s never pleasant to listen to.

The answer is: All other things being equal, you’ll need more power to drive more speakers—but all other things are never equal. Surround adds speakers and channels, but one of those speakers is usually a powered subwoofer, so the five or more main amp channels are less burdened by bass reproduction. Another way to make surround practical—and now we’re getting close to the fundamental point of any Klipsch speaker review—is to improve the loudspeakers’ sensitivity so that you get more usable volume per watt of amplifier power.

The Klipsch Synergy B-20 has a rated sensitivity of 92.5 decibels with 2.83 volts at 1 meter. Every 3-dB reduction in sensitivity requires a doubling of amplifier power to achieve the same volume level. So this speaker requires only half the power of a speaker with a similarly derived rated sensitivity of 89.5 dB. If you surf around, you’ll find loads of same-sized speakers with that sensitivity or less. As a practical matter, an average A/V receiver—even a relatively affordable one—will run five to seven of these speakers to pretty high levels in a modest-sized room. This doesn’t eliminate the possibility of amplifier clipping, but it does reduce its occurrence at reasonable listening levels. And buying a more powerful AVR will make a good thing better.

How does Klipsch do it? The Synergy speakers have horn-loaded tweeters. These guide and focus the speaker’s high-frequency output toward the listener, producing higher volume levels in that direction. The technical explanation is that the horn helps to match the acoustical impedance of the diaphragm more closely to the acoustical impedance of the air in the room, resulting in higher sensitivity. Here the story moves from dry numbers into something with more human interest—namely this company’s long tradition of building horn-loaded speakers, which began with Paul W. Klipsch of Hope, Arkansas (birthplace of former President Clinton). Klipsch patented his Klipschorn in 1945 and remained active in the company that bears his name until just a few years before his death in 2002.

Anchoring the Corners
For this review, I used the Synergy B-20, a monitor-size or bookshelf speaker ($279 per pair) to anchor the four corners of the soundfield. The job of reproducing dialogue goes to the C-20 center speaker ($299). Both models’ tweeters are deeply recessed into Klipsch’s famous Tractrix horns. Bass-making duties belong to the SW-450 subwoofer ($450).

The B-20 is a basic two-way design with an oval port on its back. It’s no surprise that the B-20 and C-20 share similar 5.25-inch IMG (injection-molded graphite) woofers—the C-20 has two of them. More unusual is the difference in tweeter sizes. Both models have aluminum-diaphragm tweeters, but the C-20’s tweeter is 1 inch, while the B-20’s tweeter is 0.75 inches. The C-20’s larger tweeter also operates within a larger horn, 4.3 inches tall versus the B-20’s 3.5 inches. As a possible alternative, the C-10 center ($199) matches the B-20’s tweeter size but has smaller woofers.

I asked the Klipsch people about the tweeter-matching issue. Their response: “Since all Synergy tweeters have an aluminum diaphragm, they are all timbre matched. Output and power handling will be greater with the larger tweeter, but the tonal quality will match.” Experience tells me that timbre matching is a much more complex affair than simply using the same diaphragm material, but my listening confirmed that the timbre matching between the two speakers was in fact pretty good in a subjective sense (see HT Labs Measures for the objective view).

The center also includes a new design feature that Klipsch calls linear travel suspension. Its tweeter has a separately attached surround encircling its diaphragm (as opposed to stamping or pleating the edge of the diaphragm material itself). This allows for more piston-like tweeter movement and reduces some forms of distortion. The C-20 has this in common with some of the Synergy floorstanding models; however, linear travel suspension doesn’t extend to the B-20’s smaller tweeter.

The differences don’t end there. As a center speaker, the C-20 has the predictable horizontal enclosure—but it’s made of molded plastic. Hence, the C-20 weighs a pound less than the B-20, which sports a medium-density fiberboard (MDF) enclosure. My contact noted that the “acoustically inert polymer cabinet” reduces internal standing waves and aesthetically harmonizes with the plastic bump on the top surface of the bookshelf model. The center has an adjustable foot that lets it fire at different angles. That’s helpful when it has to go above or below the screen at a different height than the left and right speakers.

The SW-450 subwoofer has a single down-firing 10-inch woofer in an enclosure with a large port in the back. Its amplifier is rated at 200 watts continuous, 450 watts peak. Associated equipment included a Rotel RSX-1550 A/V receiver and OPPO BDP-83SE universal disc player. All movie demos were on Blu-ray Disc, although I wasn’t always lucky enough to get a lossless soundtrack.

Sotto Voce versus the Roar of War
Episodes 9 and 10 of The Pacific, in DTS-HD Master Audio, threw two different challenges at the Synergy system. Episode 10 concerns itself with the lives of American heroes returning to civilian life after World War II. This intimate, low-key drama is all about dialogue. I took the opportunity to shift around the sofa to see if the center was beamy or overly directional, a vice of some horn-loaded speakers.

The vocal image was not only remarkably clear and solid (as I expected), it was also surprisingly un-beamy as long as I stayed on the sofa. Minor changes of posture or movements around the sofa didn’t result in tonal or spatial shifts large enough to be disorienting.

Episode 9 integrates the relentless noise of war with shouted or spoken dialogue. The music remains discreetly beneath the surface, always deferring to effects and voices. All of these elements merge into the story’s emotional flow. They do so in such a seamless way that after 20 minutes or so, I utterly forgot I was reviewing speakers. I had moved from home theater to the Pacific theater. Rain falling on mud-drenched soldiers sounded close and spattery. In a more pastoral scene, when the soldiers get a chance to relax, birdsong suspended between the front left and surround left speakers made me jerk my head toward the window. I was under a powerful spell cast by content and hardware.

The Experiment also arrived in DTS-HD Master Audio. Its what-if scenario is about noncriminals studied in an increasingly scary prison-like setting. While there’s nothing special about the opening music itself, the way it enveloped me prompted a notebook-preserved “wow.” I could hear the subtle bowing of violins, which is rare in movie soundtracks. In this case, it was supported by both the mixer’s artistic preference and the speakers’ high resolution.