Product Review

DRIVER'S ED
Remember when it was coloring time back in kindergarten, and the teacher would always tell you to stay between the lines? Well, it seems that many loudspeaker designers learned by those same rules, as almost every so-called new speaker design uses just another combination of the same old dome tweeters and plastic coned woofers. Don’t get me wrong, driver choice is only one part of what it takes to make a good loudspeaker, and conventional technology can produce sensationally good results. But if you really want to hear what’s possible when you move beyond standard technology, it pays to check out some speakers that use drivers you might not find in the design book.

Unlike the other components in an audio system, speaker design has basically stood still for more than 30 years. Sure there’s been a trend toward taller and slimmer cabinets, but the actual components themselves, the woofers, midrange drivers, and tweeters used in most speakers can trace their design origins back to the AR Model 3 introduced way back in 1958. The problem is that in the decades since then, our listening habits have changed dramatically.

Instead of playing LPs featuring Herb Alpert or Elvis singing “Viva Las Vegas,” today’s speakers must be able to replicate the helicopter crash scene from Black Hawk Down. These changes, along with the current trend of mounting the speakers up on the wall, require a reappraisal of what type of speaker technology is needed to produce the best results.

Rockin’ Ribbon 
Tweeters using a thin metal ribbon have been around for decades, but can they stand up to the demands of today’s listening habits?
Ribbon tweeters have always been kind of like the loudspeaker equivalent of a butterfly. Beautiful, yet fragile in the extreme. Typically, they have been most popular with those who value quality over quantity, where letting it rip might involve winding up the volume a bit during the finale of Beethoven’s Ninth, rather than trying to make our ears bleed while watching 2 Fast 2 Furious.

BG Corp, the speaker company formerly known as Bohlender-Graebener, uses ribbon tweeters to produce high frequencies. Ribbon drivers are known for their quality, not quantity, meaning they sound great but don’t play loud.
A driver, like a ribbon, that is much taller than it is wide is usually called a line source, and in the case of the BG R-17i we have a tweeter ribbon that is about 2 inches long, but less than a half inch wide. Tweeters will start to exhibit limited dispersion when they become larger than about an inch in any dimension, and a line source like the BG ribbon will have excellent dispersion across its short dimension, but will be quite directional above and below the longer axis. Designers will take advantage of this phenomenon to create a speaker that can cover a wide lateral range of seating locations, yet deliberately restricts the amount of high-frequency energy reflecting off of the floor and ceiling. In other words, this means that a ribbon tweeter can reduce the contribution of the room to the sound, resulting in clearer, less muddled music and movie effects.

Because of this unusual directionality, the ribbon tweeter in the R-17i can rotate 90 degrees, should you plan to mount the speaker on its side for use as a center channel. Flanking the ribbon is a pair of 4-inch woofers, followed by a pair of 4-inch passive radiators. Covering everything is a semicircular perforated silver (black is an option) metal grille––resulting in a wall-mounted R-17i looking a bit like a half section from some futuristic piece of pipe.

It’s difficult to describe a tweeter that adds very little character of its own, and what I first noticed with the R-17i is how rich the tonal palette had become. Each different cymbal in a drum kit had its own distinctive qualities, and even things as subtle as the ambient outdoor noise in almost any movie became particularly rich and vivid through this speaker. The bass  was tuneful, even though its impact was somewhat limited, and as with most on-walls, I would suggest augmenting the bottom end sound with a subwoofer.
 

Due to their tall and thin shape, ribbons act as a line source, which means the sound tends to emanate straight out from the speakers. Very little energy radiates toward the floor or ceiling, which cuts down on destructive boundary reflections.

Worried that these speakers might not be able to handle really dynamic material, I loaded up the scene in Kill Bill where Uma Thurman is fighting off hundreds of assassins. Even at an uncomfortably loud volume level, the sound remained crystalline and transparent, with no sign of distress from either the woofers or tweeters. BG rates the power handling at a fairly modest 100 watts, so evidently some care needs to be used, but in practice I never had a problem.

The R-17i does a pretty credible job of delivering a believable sense of image depth, which is unusual for a wall-mounted speaker. Along with its ability to focus a center image, I found a single pair worked well—for a centrally located listener—without adding a center channel.


Unless the cabinet is really huge, you probably won’t get much bass from an on-wall speaker. Michael paired the Klipsch Synergy Series SLX speakers with the Sub-10 to augment the lower octaves.

These are great speakers for someone who values the subtleties that separate the ordinary from the extraordinary, and who isn’t looking to knock down the walls with the latest action flick.

However, if you really must have both, BG can always supply one of the R-17i’s big brothers.

RATING: ELEVATED
Description: BG Corp R-17i LCR speaker
High Points: Subtle, transparent sound; exceptionally good imaging for an on-wall
Low Points: Not for head bangers; quite large
Contact: BG Corp, 775.884.1900, www.bgcorp.com
Price: R-17i LCR, $499

Back To The Future 
Is a horn-based speaker like the Synergy SLX more relevant today than ever before?

Imagine that you’re tailgating at a football game and you want to tell your buddy across the parking lot that the brewskies aren’t getting any colder. Instinctively, you hold your cupped hands up to our mouth to project your voice out and forward, kind of like a megaphone. That’s similar to how a horn speaker works. They’ve been around since the dawn of audio, but back then amplifiers had little power so the speaker used a horn to help produce a realistic volume level. Now there is no shortage of amplifier power, but ultra dynamic movie soundtracks are pushing the actual drivers themselves to the limits of what they can do without a meltdown. While it’s not too tricky to make a woofer that can handle gobs of power, creating a tweeter with super high power handling isn’t so easy. Using a horn helps us get the high output required without having to push the driver so hard.


Like a ribbon tweeter, the horn tweeter in Klipsch’s Synergy Series helps project sound toward the listeners, and not toward room boundaries that can muddy the sound. The difference is that the Klipsch speakers can play loud and dynamic.

Klipsch and horn speakers are practically synonymous, and the Synergy SLX puts a horn-loaded tweeter between a pair of conventional woofers in a tall, slim enclosure that you can wall mount next to a flat-panel screen. While it might seem that a pair of 4.5-inch woofers would be too puny to keep up, the SLX is designed to pass the deep bass duties over to a subwoofer. I paired it up with Klipsch’s self-powered Synergy Sub-10, resulting in a package that could handle just about anything you could throw at it.

Included in the box is a clever snap-in wall-mounting bracket that allows you to rotate the speaker to achieve the best image focus. The speaker can also be turned on its side for center channel duties, and an optional floor stand provides more positioning options. The speaker itself looks a bit busy to my eye when naked, so the slip-on charcoal colored grille cover was a welcome addition. While the plastic front baffle where the drivers are mounted seems to be pretty thick and solid, the SLX’s rounded back makes a distinctively hollow sound when you give it a knock. This potentially resonant nature could be a real problem in a full-range speaker, but in the limited-bass SLX, it becomes less of an issue.
The Synergy SLX speakers use a horn-loaded tweeter to help reproduce realistic volume levels. The horn creates an effect similar to cupping your hands around your mouth to speak to someone that might not otherwise hear you. The speakers can be wall-mounted or can sit on these really groovy stands.

Getting a good blend between the SLX and the SUB-10 proved to be quite tricky in my room, and I ended up using a 100 Hz crossover for the most seamless transition. Once everything was tuned in I found the SLXs to sound dynamic and exciting, and the impressively low distortion encouraged me to crank it up louder than I would normally listen. The horn tweeter projects the sound forward into the room in way that somewhat lessens room reflections, making the sound particularly clear and coherent. Nitpicky audiophiles might criticize the SLX’s slightly lean response and say that the tweeter is just a bit peaky, but this would miss the essence of the speaker’s considerable strengths.

Overall, the SLXs do a terrific job in their primary role as on-wall speakers for video or home theater use, and are highly recommended.

RATING: ELEVATED
Description: Klipsch Synergy SLX LCR speaker; Synergy Sub-10 subwoofer
High Points: Clear dynamic sound; easy to drive; clever mounting arrangement
Low Points: Plastic construction; tricky to blend with sub; a bit lean and peaky sounding
Contact: Klipsch USA, 800.554.7724, www.klipsch.com
Price: Synergy SLX, $350 each; Synergy SUB-10, $400

Paper, Plastic, or Metal? 
RBH’s WM-24 takes a more metallic approach to audio reproduction.

It all comes down to physics. In a perfect world any speaker driver would combine infinite stiffness, with zero mass. Unfortunately, in the real world things that are really stiff also tend to be pretty heavy, so the trick for creating a speaker is to find materials that are somehow both light and stiff at the same time.


The WM-24s come in an extruded-aluminum, wall-mountable enclosure. The bass response from the speakers is tuneful and more extended than you might expect, but you’ll want to add a subwoofer for better impact and low-end response. We used the MS 10.1.

Aluminum is a great choice for dome tweeters, where the small size and tiny movements required allow you to use a dome that is incredibly thin and light. Once you move up to a woofer however, the size and mechanical strength required results in a cone that’s much heavier than a paper or plastic equivalent, and the added inertia will generally make the speaker slow to respond and difficult to drive. With the WM-24, RBH gets around this by going with a pair of 4-inch aluminum cone woofers, and then adding a pair of passive radiators to extend the bass deeper still. When the speaker is mounted up on a wall, this array delivers enough bass to let you get by without an additional subwoofer, but we paired it up with RBH’s MS-10.1 sub to add some real heft.

Housed in a beautifully made extruded aluminum enclosure, the WM-24 is solid enough to bruise your knuckles should you attempt a rap test, and it comes complete with a wall mounting bracket and interchangeable silver or black grille covers.  My only gripe is with the speaker connectors, which are recessed into the back of the speaker in a way that makes them particularly difficult to tighten.



RBH’s WM-24 speakers use metal drivers, which are great for their rigidity, but can be difficult to drive due to their weight. These speakers get around that by using a pair of smaller drivers and a pair of passive radiators to boost bass response.
With all of that metal around, you might expect the WM-24s to produce a hard and aggressive in-your-face kind of a sound, but RBH has managed to avoid this by matching up the metal woofers with a soft dome tweeter. The resulting sound is actually quite easy on the ear and just a little laid-back, yet it can deliver an impressive sense of impact when required. The bass is tuneful and more extended than most speakers of this type, although to get the full impact from an action flick, you’ll still want to supplement it with a subwoofer.

While they are somewhat less sensitive than average, the WM-24s can still be driven effectively by just about any current A/V receiver or amplifier. I had no trouble getting plenty of output using a 35-watt Sharp SD-PX2 receiver, although a 100-watt Linn Chakra power amp introduced an additional dimension of control and dynamic capability. The MS 10.1 subwoofer actually uses two 10-inch aluminum drivers, but its built-in 250 amplifier ensures that there’s plenty of power on hand to keep them in check.

RBH’s WM-24 speakers are an excellent choice for everyday listening. Their smooth, easy-going sound allows you to keep listening over the long haul without becoming fatigued.

RATING: SOLID
Description: RBH WM-24 LCR speaker; MS-10.1 subwoofer
High Points: Smooth refined sound; beautifully built; choice of grille colors
Low Points: No tabletop or floor stands; speaker wire binding posts are fiddly to tighten
Contact: RBH Sound Inc., 800.543.2205, www.rbhsound.com
Price: WM-24 LCR, $449 each; MS-10.1, $800