Canton Karat Reference 2 DC loudspeaker
The Karat Reference 2 DC—yes, that name will never trip off the tongue—was introduced to celebrate Canton's 30th anniversary and is the result of the company's design team, headed by Frank Göbl, in effect being given free rein to design both the drive-units and the system that would use them.
With its metallic-silver lacquer finish (alder and beech veneers are also available), the Reference 2 DC is a handsome speaker standing some 4' tall. Despite its mass and bulk, it doesn't visually dominate a room, because only the upper-frequency drivers are mounted on the enclosure's narrow face. The 12" woofer and Auxiliary Bass Radiator (ABR) are mounted opposite each other on the large sidewalls. I first saw this idea on the Acoustic Research AR9 from two decades ago, and it resurfaced in the early 1990s on the AudioPhysic Virgo. Not only does it allow the speaker to have a slim frontal profile, which benefits upper-frequency dispersion; it also ensures that the cabinet's largest panels, whose vibrations are the most difficult to control but which couple most efficiently to the air, are facing away from the listener.
Even so, the Karat Reference's trapezoidal enclosure has been heavily braced and reinforced to minimize panel vibrations, and is constructed from a laminate of two different particleboards with different densities. To minimize the effects of internal space resonances, there are no parallel internal surfaces, and the interior is divided into several different-sized "vaults," according to Canton's White Paper on the design.
The 2 DC's drive-units have been designed with the latest in finite-element analysis and magnetic-circuit simulation programs, to maximize linearity at large diaphragm excursions and minimize the prevalence of unwanted diaphragm breakup modes. The 1" metal-dome tweeter handles frequencies above 3.2kHz. Its low-mass dome and coil former are formed in one piece from what is specified as an aluminum-manganese alloy and uses a powerful neodymium magnet with a vented polepiece to achieve the necessary high sensitivity.
The twin 7" midrange units are constructed on diecast polycarbonate chassis and arranged above and below the tweeter. Canton calls this array "D'Appolito," but this is not strictly true: the crossover's acoustic slopes are described as fourth-order, with 24dB/octave slopes. To the best of my understanding, the benefits regarding vertical dispersion that accrue from Joe D'Appolito's array arise when odd-order filter slopes are used.
The midrange units also use a neodymium magnet and an "aluminum-manganese" diaphragm—it's actually an alloy of aluminum and magnesium—this time in the shape of a cone but with a dustcap of the same material continuing the profile to result in a dish shape. This smoothly extends the unit's response an octave above the crossover frequency. The maximum linear excursion of the 4.75" diaphragm is said to be an astonishingly large 0.87", but below a 110dB SPL the excursion doesn't exceed 0.12", which should result in low distortion.
The 12" woofer is constructed on a diecast magnesium chassis and features a pulp cone doped with graphite fibers, this terminated with a rubber half-roll surround to give good linearity and high excursion capability. The ABR uses a flat diaphragm, again terminated with a large rubber half-roll surround. Despite a moving mass of only 5oz, the ABR is claimed to have a resonant frequency below 10Hz, to optimize its reflex behavior. The "DC" in the Karat Reference 2 DC's name refers to Canton's Displacement Control circuitry, which reduces the level of infrasonic signals both to maximize low-frequency dynamic range and to minimize the production of midbass muddiness.
The 16-lb crossover is mounted in its own sealed, decoupled subenclosure behind the upper-frequency drivers. It uses hand-wound coils and ICW capacitors. Electrical connection is via two pairs of sturdy binding posts at the base of the rear panel.
After some experimentation, the Karat Reference 2s were set up in pretty much the positions in my dedicated listening room where the Wilson Sophias had worked so well last July: 30" (left) and 72" (right) from the side walls and 54" from the wall behind them (all distances measured from the woofer dustcaps). The woofers were on the speakers' inner sides, the passive radiators facing the sidewalls. The Cantons were not toed in all the way to the 10'-distant listening seat; my ears were level with the 37"-high tweeters.