KEF Q900 loudspeaker
KEF and I go way back. As a very young man in the 1960s, I was obsessed with building speakers, and that was just about the time that KEF founder Raymond Cooke was revolutionizing driver design by using new synthetic materials for cones and surrounds, and experimenting with such innovations as transmission-lineloaded midrange drivers. I found it all very heady and, by direct import from the UK, obtained versions of the oval, flat-diaphragm B139 woofer, the Bextrene-coned B110 and B200 woofers, and the T-15 and T-22 dome tweeters. Fifty years ago, this was all cutting-edge speaker technology.
In the years since, KEF has continued to push the drive-unit envelope with developments like the Uni-Q coaxial driver, and such spectacular loudspeakers as the Muon, the Concept Blade, and, of course, the KEF Reference models, which have been so well received in these pages. In February 2008, John Atkinson said that the KEF 207/2 was "overall the best-sounding full-range speaker I have used in my current listening room," and in July of that year Wes Phillips described the smaller 201/2 as "an absolute gemif not flawless, then damn close" (). And in February 2006, Robert J. Reina had been nearly as effusive about KEF's midpriced iQ9.
Now, in recognition of their 50th anniversary, KEF has completely redesigned their lowest-priced Uni-Q models, the Q series, which extends from the smallest two-way, the Q100 ($499/pair), to the subject of this review: the 2.5-way, floorstanding Q900 ($1598.98/pair; sold singly for $799.99). Despite the fact that these prices are in the range of the generic boxes cluttering the sales floors of big-box outlets, the Q series is chock-full of KEF's characteristic design innovations. That's what struck me when I saw the Q900 at the 2010 CEDIA Expo; the combination of technology and apparent high value stoked my interest in getting a pair shipped to my house in Connecticut.
The Q900 is a big speaker. More than 3.5' tall, 14.1" wide, and 12.7" deep, it weighs almost 50 lbs, sits on a sturdy base with lethal-looking spikes, and sports FOUR (count 'em) FOUR 8" aluminum-cone units. You'd expect it to play loud and deep. KEF maintains that the Q900's "rectilinear form" provides a larger internal volume than would be possible with curved panels, and of course, for a given footprint, this is so. However, the use of large, flat cabinet panels does raise a concern about panel vibrationsunless those panels are braced and/or damped.
Given the Q900's large size and relatively light weight, I suspected that KEF had approached this problem more by damping than by bracing. However, KEF told me that they determined, from listening and laser-Doppler vibration analysis, that the most important part of the cabinet in this regard is the front bafflewhich, surprisingly, is 28mm (1.1") thick, this increasing to 35mm (1.4") in the area where the Uni-Q driver is mounted. I was able to detect some vibrations on all surfaces, but these seemed minor and uniformly distributed. KEF describes the cabinet's finish as a "paper veneer," which provides an eco-friendly and easy-care rendition of exotic woods. Well, my review samples looked just fine in Black Oak (English Cherry and European Walnut are also available), but they sure look like speakers, and won't turn any heads at the Milan Furniture Fair.
The rigid bases and sturdy spikes ensure a stable stance, and conveniently permit fine-tuning from above. However, since I usually set my main speakers on hardwood, just off the carpeted area, the absence of any alternative footers or protective pads for the Q900s had me scrambling for some old spike pads I'd buried deep in the equipment closet. Of course, $2 worth of quarters would also have sufficed; until KEF provides another option, consider that a necessary additional expense.
Uppermost on the front panel is the 8" Uni-Q driver, at its center a 1.5" vented aluminum-dome tweeter. This tweeter's sizethe other KEF Q models have only a 1" domepermits a lower crossover point from the mids to the highs: 1.8kHz vs 2.5kHz or higher. It is fitted with the Tangerine waveguide developed for KEF's Project Blade, to prevent untoward changes in dispersion at the crossover frequency and above. The Uni-Q's lower-frequency cone diaphragm and motor share their enclosure with an 8" aluminum-cone passive radiator. Below those is a second sealed enclosure, this shared by an 8" aluminum-cone woofer with 2" voice-coil and another 8" passive radiator. Thus all four cones, active and passive, contribute to the Q900's low-frequency output, but the lower woofer is rolled off in the low midrange to make this a two-and-a-half-way system.
The Q900 has two pairs of speaker terminals, to accommodate biwiring or biamping. I'm generally leery of ascribing any audible advantages to biwiring or passive biamping over the use of an adequately hefty cable or adequately powerful single amp. Nonetheless, KEF gives you the opportunity to follow your star, and has also provided a rather neat implementation in the form of two terminal linking controls that eliminates the use or potential loss of those fiddly metal links. The upper terminals connect only to the tweeter; the lower terminals connect to both the woofer and the Uni-Q driver's main motor. Rotating the linking control knobs to the right connects the two pairs of terminals to allow the use of a single cable; rotating it to the left disconnects them to allow biwiring or biamping.
Plug it in, plug it in
I connected the KEF Q900s to my Bryston 9B STT power amp with Kubala-Sosna Fascination speaker cables, turned off the Audyssey room-calibration software in the preamplifier-processor, and set the pre-pro to Direct so that the KEFs would run full-range on their own, sans subwoofer(s).
All that cone area led me to expect a very full, rich balancebut that's not what I heard. My first impression of the Q900 was of a well-balanced sound that was, if anything, a bit lightweight. However, that reservation faded quickly, as I stopped comparing the KEFs to the Audyssey- and sub-assisted system they'd replaced.