KEF Reference 203/2 Loudspeaker (TAS 204)

The KEF 203/2 is a medium-proportioned floorstander that occupies the sweetspot in KEF’s prestigious Reference line—a range of seven models—the majestic, four-way, 145-pound Reference 207/2 holding court at the summit. Standing roughly 40” tall the 203/2 is a three-way, four-driver, bass-reflex design that features the latest generation Uni-Q driver (KEF’s proprietary coincident midrange/tweeter). A pair of 6.5” woofers are tasked to cover the frequency band below the 300Hz cutoff of the midrange. The curved-section cabinets are a beech-ply construction with heavy internal bracing. Both mechanical and acoustic damping have been engineered to match a specific volume for each independently loaded driver. KEF notes that independent loading of the bass drivers also reduces the height of each internal compartment and pushes the standing waves to higher frequencies where they are easier to control without sacrificing sensitivity and dynamics in the bass passband.

By any measure build-quality is impeccable. Surfaces are satin-smooth and seamless. The 203/2 actually looks larger in pictures than in person and is, in reality, a fairly small footprint floorstander¬—a perception heightened by the hemisphere of the Uni-Q containment dome that caps the enclosure. And KEF certainly knows how to coddle its Reference customers: The impeccably packaged speaker system arrives with a bespoke satin-finished wooden box roughly the size of a fine humidor. The Reference logo is regally inlaid on its lid. Posh, indeed. Known as a care-pack its contents include documents, spikes, wider footers for wooden floors, locking nuts (for fine adjustments), a wrench, and a heavy-duty circular level. Recognizing that not all owners will opt for the triwire/triamp option, KEF also includes spade/banana jumper wires for bridging the three (!!!) pairs of speaker terminals.

Crossover components are computer-modeled for precise phase and amplitude behavior, and the boards are decoupled to isolate them from cabinet-wall vibration and internal acoustic pressures. Hand-soldering is used throughout, as is KEF’s own graded OFC cable. Grille covers are pin-release. The circular cover that protects the Uni-Q uses gentle magnetic fasteners that seem to beg the listener to set them aside. Sensitivity is a level-headed 89dB.

Part of the Reference Series’ white-glove treatment is the Uni-Balance feature—rear-panel adjustments that tame boomy bass output due to wall/corner proximity and a four-position brightness control that compensates for the room’s treble absorption characteristics. Uni-Balance comprises three rear-panel terminals—the LF adjust terminal comes factory preset to the flat setting for “free space” positioning. When the screw cap is removed bass is rolled off about 2dB. The HF adjust has twin screw caps that permit up to four distinct settings ranging from +0.75dB to – 1.50dB at 2kHz and up. These changes might seem miniscule, but my experience with the Ref 203/2 validated that the range of different sounds it provides can be a real help when dealing with room anomalies and oddball recordings.

By any measure, KEF’s Uni-Q driver technology is the star power that connects each Reference model to the other. It originally debuted in 1988, and like the coaxial drivers that preceded it was developed in pursuit of a high-end holy grail—point source-type time alignment and uniform directivity. (In KEF’s words, “The directivity is often referred to in engineering terms as the ‘Q’, and the ‘Unifying’ of the ‘Q’ gives rise to the name ‘Uni-Q.”) Though visually similar to its forbears the latest iteration differs substantially. According to KEF, there’s wider dispersion due to a shallower polypropylene midrange cone. The titanium tweeter has a new vented three-magnet motor system with a two-piece, compound dome for higher rigidity—improvements that smooth response and widen dynamics. Controlled matching of the tweeter dome angle and midrange cone angle has improved high-frequency response. The net result is wider dispersion and more uniform power response.

For my own edification I asked KEF whether the 6.5” diameter was a particular sweetspot for coaxial drivers. TAD opts for a similar spec in its all-beryllium coincident transducer, for example. KEF seemed to agree and replied that the “6.5” Uni-Q could cross over a lot lower, or even run full-range with a full surround and longer coil. But there were also advantages to limiting it to midrange use, namely the reduced excursion of the cone and “the smaller/flatter midrange surround presents less of a diffracting edge to the tweeter's radiation.” And, of course, the voice coil is shorter and lighter. The precise crossover frequency will depend on the bass or mid/bass drivers and their directivity, size, and bandwidth relative to that of the Uni-Q. Anywhere from 150Hz to 600Hz is feasible for midrange-only use, depending on the target system.