Bohlender-Graebener Radia Series Speaker System

The thrill of exotics.

The Radia Series speaker system is the latest development from what can be considered a seriously thick branch in the speaker-manufacturing tree. You may not be too familiar with the Bohlender-Graebener name; but, when it comes to hybrid planar magnetic driver technology, the name isn't uttered without a good deal of respect.

A couple of years after B-G was launched, HT reviewed an early iteration of the present review system. The individual speaker nomenclature has not changed from the earlier model, except for the addition of the letter "i" (for "improved") to each speaker designation. According to B-G, improvements include "new advanced Linkwitz-Reilly crossovers for improved balance and reduced phase distortion and updated planar ribbon drive units for higher efficiency, lower distortion, and extended frequency response."

What distinguishes the planar ribbon driver from more-traditional speaker technologies is simply this: Most of the frequency range is generated not by a cone driver but by a flexible membrane. The membrane is bonded with conductive traces and then suspended in a magnetic field. When the conductors are energized by an amplifier's signal, the membrane responds by moving in a push-pull fashion as the signal varies. Voilà! Sound.

For this review, I partnered the Radia system with a Samsung LCD monitor, an Onkyo DV-SP800 universal disc player, a Parasound Halo C 2 processor, Sunfire Cinema Seven Signature Edition and Simaudio Moon Aurora seven-channel amplifiers, and Kimber 8TC speaker wire.

The Speaker Array
The 520i, used as front left and right speakers, features a 50-inch-tall, planar magnetic line-source and two 6.5-inch cone drivers located in the base. This configuration allows for a claimed effective frequency range of 70 hertz to 20 kilohertz (–6 decibels, half space). The loudspeaker base is constructed of an MDF enclosure that houses the two long-throw cone drivers and the crossover components. Jutting from this base is a flat-black anodized-aluminum tower containing the planar driver. The 420i, used here for surround duties, is essentially a 10-inch-shorter version of the 520i. It claims an identical effective frequency range. The crossover design in both the 520i and 420i speakers divides frequencies at 350 Hz, allowing every frequency above the midbass to be handled by the planar drivers.

If you think the 520i and 420i need room to breathe, you'd be right, but wait until you consider the center channel, the 220i. This massive beast significantly outspans the width of a conventional 32-inch CRT and would best be situated atop a speaker stand positioned just below the viewing area. The MDF cabinet encases two 6.5-inch woofers, two 8-inch planar midrange drivers, and one 3-inch planar ribbon tweeter. Starting from the outside edge, you'll find first the woofer, then the midrange ribbon, then the tweeter ribbon. According to our previous review, the original center channel carried a soft dome tweeter in an effort to "provide broader horizontal dispersion for the high frequencies." On a subjective level, it appears that the "i" modifications have eliminated the need. In fact, the use of the tweeter ribbon may allow the frequency response to soar into a claimed 25-kHz region, beyond the range of audibility but de rigueur in today's multipurpose (SACD, DVD-Audio, and DVD) environments.

The 220i is said to drop down to 50 Hz, a point roughly 10 Hz above the pressure level generated by the lowest open string on an upright bass, which goes a long way toward explaining why B-G released their own complementary subwoofer earlier in 2004. At 14.5 inches high by 13.5 wide by 17.5 deep, the Radia 210i subwoofer is a relatively compact enclosure that manages to house a pair of 10-inch Kevlar drivers and a 500-watt BASH amplifier. The 210i breaks the rectangular standard pervasive in most subwoofer designs: Along one plane, you'll see approximately one-fourth of a rigid cylinder breaking out of the side. More than an aesthetic conceit, this cylinder houses both drivers, which are situated so that their cones face opposite directions while being wired in phase. According to B-G, "Recalling Newton's Law, where for every action there is an opposite and equal reaction, the movement generated by the woofer's cones causes the reactive forces of each woofer to effectively cancel one another." B-G has trademarked their approach to woofer placement as a Reactance Canceling Design. The subwoofer's onboard amplifier is said to allow for transient peaks of well beyond 1,000 watts, with the net result that the drivers can travel more than 2 inches, equaling the output of a "conventional 14-inch subwoofer."

Tricky Setup
Although my listening room is oddly shaped, I've had little difficulty getting maximum replay through most conventional cone-driver speaker arrays—including soundstage accuracy, vertical dispersion, and tight bass output. At the very least, I know how to determine when the room interferes with a particular setup. That was not the case with the Radias. That's because B-G calls for specific speaker placement, going as far as providing a schematic with angles and distances recommended in relation to the seating position. The surrounds, for example, need ample breathing room away from corner boundaries; also, the listener is warned to avoid placing the surrounds to the sides of the listening area and instead is told to position them in a "subtended angle" between 90 and 120 degrees, a minimum of 7 feet on either side behind the seating position.

After trying to max out the situation at home without success, I eventually dragged the whole kit and caboodle to our studio in order to generate a fair and balanced review. B-G's directions, by the way, are exceptional, and studio setup proved to be a snap. The soundfield snapped into focus, too.

Sound: The Point of It All
The first thing I noticed was that the system has incredible resolution of micro-details. The Diva sequence in The Fifth Element sounded particularly spectacular. You could readily hear the breathy quality of the Diva's voice, her soaring range, the sharp metallic nature of ammunition puncturing sheet-metal ductwork, and the depth of the massed cellos and basses wallowing in the background. Initially, the system sounded a bit compressed, but this characteristic was attenuated significantly when I used the Simaudio Moon Aurora amp, which allowed the system to eke out even more micro-details.

Of course, excellent transient response can be a given with a panel-based system like this one. It is, rather, the quality of the design as it relates to nuance. Take, for example, the underrated film Underworld. The mood is dark, at times crackling with the energy of electricity and thunderclaps positioned variously around the room and at other times with the aural sense unique to rain falling on concrete. The Radia system captured these moods, subtleties, and sound positions without fail. Hearing the sound of skin split and bone crack when a human transforms into a werewolf is hair-raising stuff. Without such aural revelations, the movie can seem threadbare; however, with a good system like the Radia, the movie becomes a gripping tale.

The Radia system can fill a soundstage quite well, behave itself with music, and portray width and height when necessary. To split hairs, I have heard a bit more depth in the soundstage with other similarly priced systems. Also, while bass wasn't lacking, as evidenced by the tight thunderclaps in the opening of Underworld, I wondered how an extra Radia sub would have helped generate that oomph factor that moves home theater to another level. Finally, there was the minor issue of the spiked feet. While appealing to the eye as they sat in their brace crossmembers, the spikes would not readily punch through the carpeting and pad when I installed the system in my home. It never felt as if the speakers were fully grounded.

Other than these minor nits, for nearly $11,000, this system is definitely worth a listen if your room is on the large side and you like exotic-looking gear that will transport you into the world of film. In order to squeeze out the greatest amount of information, you'll need to drive the array with an equally competent and sophisticated amp, processor, and universal player. Lesser-quality partners simply will not do if you want to get your money's worth from the Radia Series speaker system.

• State-of-the-art hybrid planar technology
• Excellent transient response and engrossing detail

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