Monthly Archives: November 2012

KEF LS50 Further Thoughts

I have owned these speakers now for about a month and a half, so it’s time for some updated impressions.

I have listened in the living room on the big rig and in my bedroom system. In both cases, the speakers acquitted themselves quite well. I take the bedroom performance quite seriously, BTW (ahem). I like to listen there late at night and often leave the system playing softly as I sleep. Speakers that have significant performance shortfalls can lead, rather than to enhanced sleep, to 3AM wake-up calls to turn the damn system off! The LS50 passed this test with flying colors, making sleep time more pleasurable and more anticipated than even my old age and borderline laziness can on its own.

The speaker did well in the living room environment, filling this large-ish space well at reasonable levels of playback. The soundstage was especially notable, it did not have the height illusion that a planar or a physically large speaker can conjure, but the rest of it was quite fine, befitting the way the particular recording was made.

Of course, no small speaker will produce prodigious bass and that is true here. But it passes the bass “Mendoza Line” test handily. (Mario Mendoza was a major league ballplayer who was (in)famous for hitting around .200 year after year with his main contributions on defense. So .200 became the “Mendoza Line”, MLB jargon for barely adequate. The ProAc Tablettes bass is at the Mendoza Line, for example. Ironically, Mendoza finished his career above the Mendoza Line…)

So with the obligatory bass disclaimer out of the way, we can look at what this speaker excels at. There is an overall sense of transparency, as though you can hear through the speakers to the essence of the recorded performance. This comes from a number of attributes. The tonal balance is quite good, the limited bass extension is balanced by a less than insistent treble and a generally flat midrange. I say generally because there is not quite the midrange smoothness and neutrality of something like the Harbeth P3ESR, for example, but the competition is close. Where the KEF trumps the Harbeth is in the lack of “cabinet fog”, which allows a clarity and detail the Harbeth can’t quite muster.

The other contributor to the sense of transparency is the soundfield the KEF manifests, which is a result of the concentric driver and the lack of sonic contribution of the cabinet due to its relative lack of resonance and its carefully radiused shape that discourages secondary radiation from the cabinet borders.

The cabinet quality here really can’t be overemphasized. This is actually quite a thing to hear; to realize that some of what we are used to hearing in speakers is an artifact of cabinet radiation and diffraction. Of course, in general, small speakers tend to have a certain clarity, their small size steers what resonances there are to frequencies where they can do less harm relative to a larger cabinet and provide a smaller surface to radiate the result of the resonances into the room, but the KEF shows what more can be done even in the context of a small speaker.

And kudos for the KEF UniQ driver, too. Making a generally flat driver is not easy and making a flat concentric driver is even more difficult, but the UniQ is a quite good driver as these things go. It could be argued that a heroic cabinet that allows the driver to do most of the speaking is good only if the driver is worth listening to. Here we have a driver that is worth listening to. Not perfect, as mentioned above, but competitive to even separate high quality woofers and tweeters while bringing the advantages of the concentric format to the table.

Overall, the KEF strikes me as an excellent product and something of a minor classic. It brings many strengths to the table and few weaknesses not directly related to its small size. It would seem the UniQ driver has come to maturity, the limited opportunities I have had to listen to the flagship Blade show similar levels of performance in a more full range context. As of now, the LS50 is my favorite small speaker in the moderate price range, its $1500 pair price being at the lower end of that range for a high quality mini.  I suspect the next significant step up for a small speaker application would be the Magico or Raidho which are both into five figures. Hats off to KEF for a fine accomplishment.