The other obvious change in the 207/2 is the absence of the hyper-tweeter that graced the previous version. This has been made possible by advances in the design of the tweeter itself, which have extended its range (and quality) significantly. One of the challenges in designing the high-frequency element of the Uni-Q array is presented by the space limitations imposed by the need to mount it within the midrange driver’s voice-coil. Whilst KEF have always wanted to vent the tweeter assembly, with the gains in low colouration and dynamic performance that go with the approach, reducing the volume of available magnetic material imposed too high a performance price in terms of linearity and sensitivity. But, in this latest version, they’ve finally cracked it by the clever use of three separate neodymium magnets. Combined with a new composite dome assembly in which a shallower titanium diaphragm is driven by a 25mm voice coil, the former of which also curves in to brace the dome structure nearer to its centre. Together, these changes have resulted in a significant improvement in performance at both ends of the spectrum, including pushing the first break-up mode out beyond 30kHz, thus rendering the hyper-tweeter redundant.
Naturally, such fundamental changes across the speaker’s upper ranges have necessitated revisions lower down. Although the lower mid unit has remained the same, the greater range of the Uni-Q has eased its working bandwidth. Meanwhile the bass drivers have had their output extended by some 5Hz, but more significantly it has also been re-voiced, the more natural balance achieved by the ‘Austin’ Uni-Q allowing a fuller, more authoritative bottom-end than the impressively agile but slightly dry low-frequencies generated by the original.
Other features that remain the same are the integral spirit level, triwirable crossover and Uni-balance adjustments for high-frequency level (from +0.75dB to –1.5dB in four discrete steps) and bass contour, allowing the user to compensate for placement near walls or in smaller rooms. One word of warning – the three sets of terminals on the back are there to be used. This speaker definitely benefits from bi- or tri-wiring. The bridging wires supplied are there to get you going, but if required I’d strongly recommend replacing them with either high-quality links made from the same wire as your speaker cables, or even better, a set of the Vertex AQ Mini Moncayo speaker links, which were spectacularly successful. Indeed, before installing them I was wondering whether KEF might have been a little hasty disposing of the hyper-tweeter. I needn’t have worried, as installing the Vertex links revealed the new HF unit in all its considerable glory.