KEF R107 loudspeaker Thomas J. Norton 1995 part 2

"Whoa! What happened?" I blurted aloud to no one in particular as the first bars of music rolled toward me. The left-right spectral balance was now all wrong. One channel appeared to have lost its top end, with a resultant skewing of the sound to the unaffected side. I listened more, to other material. Same result. I pulled the speakers out and set them close together. No change. I reversed the midrange/tweeter heads (they come packed separately and may be easily installed or removed by the user). The problem moved with the change in heads, indicating that it lay with the tweeter itself. Swapping amplifiers left to right only confirmed this observation.

Somewhere between the initial listening test and the new setup, one of the tweeters had lost most of its output. Why this happened remains a puzzle—one that will likely go unresolved. Perhaps it was a flawed sample that, while it appeared fine on the assembly line, was weakened by the break-in and finally failed at the very end of my first listening session. Possible, I suppose, but certainly a first in my experience.

In any event, KEF's preferred solution was to send me an entirely new pair of loudspeakers. As deadline time was rapidly approaching, and there were apparently no 107/2s in stock either in the US or the UK, the factory had to build us a pair on short notice and air-freight them from England to Santa Fe. They were so new I could still smell the finish when they arrived. Fortunately, it was dry.

Murphy just wouldn't quit, though. When I hooked the new pair up, they sounded out of phase. My external hookup was correct. Furthermore, listening to the bass alone revealed that the woofers were in phase. Apparently, the midrange/tweeter phase was internally reversed on one of the loudspeakers. But which one? Reverse the wrong one, and the relative phasing between the midrange/tweeter and woofer would be wrong on both channels, even while the left and right woofers and left and right midranges/tweeters were in proper phase with each other.

Fortunately, with direct access to the midrange/tweeter phasing via the bi-wire inputs, this was an easy problem to solve. Reverse the wrong midrange/tweeter, and the whole sound was simply wrong, with a lower midrange suckout that resulted in a clear hollowness—particularly noticeable on male voices. The Orson-Welles-as-Don-Knotts effect.

As to any quality-control problems this internally mis-wired loudspeaker might imply to the reader, I must emphasize, in fairness to KEF, that this second pair of 107/2s was assembled in haste. If I have to get a set of loudspeakers with a problem, I'll take a problem with an easy, on-site solution every time. Once this was all ironed out, the second pair of KEFs functioned flawlessly.

System
The Model 107/2s were auditioned in a system fronted by a Denon DP-S1 transport and Mark Levinson No.36 D/A converter, linked by Kimber AGDL digital coaxial cable. The amplifier was a Carver Lightstar. TARA Labs Master RSC (unbalanced) interconnect tied the Levinson converter to my reference Rowland Consummate preamp, with the preamp-to-KUBE and KUBE-to-power-amp interconnections via Cardas Hexlinks. Loudspeaker cables were Monster M1.5s.

Sound
"Whoa," I blurted again, only this time I was smiling. Not only was everything finally functioning, but functioning in a sit-up, take-notice kind of way. No, the sound didn't blow me out of the room, make my jaw drop, or generate any other kinetic activity. Remember, I had just finished evaluating another terrific set of loudspeakers: the Thiel CS7s. The sound from the KEFs was noticeably different than the Thiels, in ways that I hope will become clear shortly. The important point, however, is that I was attuned to a high standard, and the KEFs did not disappoint.

Gone was the rather bloated quality I had heard from the first pair of 107/2s in the first setup. The sound was now well-balanced, dynamic, and three-dimensional. A minor lack of soundstage imprecision was quickly cured by a slight repositioning of the right-channel loudspeaker. (Turns out it was a couple of inches closer to the listening seat than the left.) A trace of edge in the mid-treble quickly receded into the background as the speakers began to break-in.

Nothing in the 107/2's performance immediately called attention to itself. This loudspeaker was easy to listen to—perhaps even a bit old-fashioned in its lack of any spectacularly flashy attributes. The 107/2 let the music speak for itself.

The closest the 107/2 came to having a distinctive character was in its immediate, just-slightly-forward, rounded yet richly detailed midrange. Vocals were particularly well-handled—rich and vibrant, with a natural bloom. Coloration was very low, with no trace of nasality, boxiness, or chestiness. The modular cabinet appeared to be doing its job.

Both male and female vocals were equally well-served. From Gordon Lightfoot to Custer LaRue—with stops along the way with Mary Black, The Chieftains, David Wilcox, and others—nothing really caught it out or sounded wrong. Sibilants seemed to be those of the recording; if there was excess fizziness in the program material, the KEF neither covered nor exaggerated it.

Vocal reproduction is very important to me; the performance on vocals of the 107 was first-class. If I had to make a call, however, I'd say that the mids on the Thiel CS7 sounded even less colored than those on the 107/2; but the "colorations" that existed in the KEF's midrange are hard to pin down in words. They were in no way unnatural. In broad terms, the midrange of the 107/2 struck me as perhaps a little more romantic than clinically accurate—certainly a valid design choice.

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