Kharma Mini Exquisite Loudspeaker

Beauty is a Rare Thing

These descriptions bring to mind something Kharma’s Charles van Oosterum told me about his design goals—that he wants his speakers to retrieve as much information as possible without, as he put it in his Dutch-accented English, “added colorations, interpretations, and without magnifying the soundstage.” As he sees it, this is a major challenge for all speaker designers, “considering that every part used in a speaker introduces its own sonic footprint into the sound, and this on more levels than one considers at first.”

To control structural resonance, Kharma starts with carefully selected enclosure materials. For the beautifully finished and striking-looking 36" tall, 95-pound Mini Exquisite, this is a proprietary, 30mm-thick high-pressure laminate that debuted in Kharma’s $250,000 Grand Exquisite (where it is actually 40mm thick). Said to be twenty times as costly as MDF, this material offers just what van Oosterum seeks in his enclosures—an ideal combination of rigidity and internal damping. The diamond tweeter is housed in its own chamber, and substantial internal bracing and internal diffusers are built into the Mini’s entire structure. A cast and round-lipped aluminum vent is fitted into the rear-firing port found just above Kharma’s custom binding-post station, and a heavyduty base structure bolts to the enclosure’s bottom panel, into which large and pointy feet are threaded. These in turn sit on protective and non-resonant discs, whether the speaker rests on carpet or hardwood.

Speaking of diamonds, while several top speaker makers are using diamond tweeters for their extreme rigidity and lightness, Kharma is among the few to use a 25mm (one-inch) dome rather than the much more common 19mm (.75-inch) variety. Van Oosterum tells me that the diamond is made in a microwave plasma reactor in accordance with the poly-diamond-deposition method, in which the reactor is loaded with gas and the diamond is deposited on a mold to create the desired shape. The thickness of the diamond is directly related to its time in the plasma reactor, and it takes an enormous amount of energy for the diamond to reach its ideal thickness, which in this case is 60 microns—or thinner than a sheet of paper. Kharma’s U.S. importer Bill Parish of GTT Audio added that, in addition to its 25mm inverted diamond-dome, each of the Exquisite tweeter’s remaining parts—from wires to magnets to voice coil—are made exclusively for Kharma and final assembly is done inhouse. As you might imagine, such tweeters are both extremely delicate (a protective removable screen is part of the kit) and costly items— roughly the same price as a case of first-growth Bordeaux.

Similarly pricey (if not nearly as) and just as fragile is the 7" ceramic bass/midrange driver. Protected by a mesh grille to keep it, too, from ending up like Humpty-Dumpty’s shell, the ceramic mid/bass driver in the Exquisite series differs from most others, including those in other Kharma models, such as the terrific little Ceramique 3.2 that had been my reference until the Mini came along. As Bill Parish explained it, “All drivers have a resonance frequency, and ceramic cones are no different. They actually ring (you can here this in non-Kharma products that use ceramic cones).” In the Ceramique series, Kharma addresses this ringing by placing a notch filter in the crossover, outside the audible frequency range. In the Exquisite series, Kharma uses a somewhat different method, hit upon by pure chance. It seems that one day while eating lunch at an outdoor café, van Oosterum happened to glance up as a car was driving by. The vehicle’s driver had outfitted his buggy with a set of fancy rims, and van Oosterum further noticed how the car’s wheels were balanced by the use of weights. Eager to try a similar balancing act on his ceramic drivers, van Oosterum returned to his facility and soon discovered that the approach worked. Photos of the Mini’s cone reveal two black dots. This is where, after measuring each driver’s response, Kharma laser trims two holes in each cone before applying the weights that eliminate ringing. This also helps simplify the crossover design and reduces the number of component parts in the signal path.

Although Kharma is pretty secretive about the origin and values of its crossover components, I did glean that the Exquisite series crossovers use silver coils and Kharma’s own Enigma wiring, and are cryogenically treated after assembly. When I asked van Oosterum the secret to his speaker’s unusually coherent sound, he replied that “the seamlessness is created by the synergy of the crossover, shape of the cabinet, and all other parameters involved in the design” and that, “special attention has been paid to off-axis phase response, as that influences greatly the ‘source-ability’ of the speaker. Meaning that off-axis sound gets reflected by the surroundings, and the more natural the reflections are the more they will blend in with the directly perceived sound.”