LS50 vs. R Series, Uni-Q vs. Uni-Q

To Doug Schneider,

I'd be surprised if I'm the first to ask this. The LS50 is, as you noted, a remarkable speaker. But if I could get just a bit more weight and extension on the bottom, I would like to. The R-series speakers also use Uni-Q drivers, but I suspect they are not the same as, nor as good as, the one used in the LS50. And there are major cabinet differences as well. Do you think the R500, or any other KEF model short of the Blade, gets you the magic of the LS50 but with more of a foundation?

Dan Rubin

You’re not the first to ask about the LS50 in comparison to the R-series models, but you are the first to make the remark about the drivers in one not being as good as in the other. I don’t necessarily agree with that.

The cones of the Uni-Q drivers in the R-series models are a different color than the one used in the LS50, and the surrounds used for all the R-series models except for the R100 are different as well (the R100’s surround looks to be the same as that used in the LS50), but there was nothing in the R500’s measured or subjective performance to indicate to me that the Uni-Q driver used in it is inferior to the one used in the LS50. That said, the speakers don’t sound quite the same, but not necessarily because of the Uni-Q quality, but because of subtle voicing differences, which I’ll explain.

Of the two speakers, the R500 has deeper bass, which is due to the much larger cabinet size and dual woofers, and is more neutral sounding through the midrange and highs. In contrast, the LS50 sounds like it’s been voiced somewhat through the mids and highs to create a slightly different sound -- the midrange projects more fully, the highs sound livelier, and the upper bass has a little more whump -- likely done to overcome the limitations of its small size and lack of bass output. In other words, they tailored the LS50’s sound more to compensate for its inherent limitations. I don’t feel that’s a bad thing because KEF’s bit of sonic “trickery” with the LS50 worked, resulting in a tiny speaker that sounds surprisingly full, quite lifelike, and remarkably complete, providing you don’t need deep, deep bass. So the “magic” you’re hearing from the LS50 probably has mostly to do with the way KEF’s designers skillfully voiced the final design, which resulted in a sound you quite like. Perhaps I’m wrong, but that’s the way I see it.

As a result, I think it would be worthwhile to try to hear the R300, R500, R700, and R900 speakers to find out if one of those has that sonic magic you’re looking for, particularly since they all can produce deeper bass than the LS50. (I deliberately left the R100 out because its bass isn't likely to impress). I really liked the R500s in my room, obviously, and fellow reviewers Hans Wetzel and Roger Kanno both use R900s as their references, meaning they’re both really happy with that model. The R300 and R700 also look impressive for their prices. So perhaps one of those models will do the trick. If not, my next best suggestion is to try mating a pair of LS50s with a sub, which, if done correctly, could be something to hear. . . . Doug Schneider