KEF LS50 50th Anniversary Edition

KEF LS50 ($1499.99)
This is a really great little speaker, and truth be told I was smitten with the design even before I heard it. The LS50's swept-back, curved baffle, with a single rose gold Uni-Q KEF driver gives the speaker a fresh new look. The LS50 is KEF's 50th Anniversary Commemorative Model, and it's very much a twenty first century speaker.

Before we go any further let's get a few specs out of the way, the LS50 stands 11.9 inches tall, it's 7.9" wide and 10.9" deep. The speaker weighs 15.8 pounds, and the internally braced MDF cabinet feels extremely solid and inert. The –3dB down point for the low end is 79 Hertz, but the LS50 sounds more full range than that number would indicate. Unless you crave pants flapping bass there's no need to add a sub.

The curved baffle was designed to provide a low diffraction environment for the Uni-Q's ribbed 5.25 inch aluminum/magnesium woofer with a 1 inch aluminum dome tweeter coaxially mounted in the center of the driver. It sports a die-cast aluminum frame, and the tweeter has that nifty looking Tangerine waveguide that uses "radial air channels to produce spherical waves up to the highest frequencies." The LS50 is an 8 Ohm speaker, but drops down to 3.2 Ohms, and sensitivity is pretty low, just 85dB with 2.83V at 1 meter. The rear panel hosts an elliptical port, and KEF supplies a set of foam plugs to stuff in the ports if the speakers need to be placed in close proximity of walls. Heavy-duty binding posts match the quality feel of the rest of the speaker. There are no provisions for wall mounts or brackets, but this isn't really the sort of speaker that sounds best hugging a wall. The MSRP runs $1499.99 per pair.


I spoke with KEF's Johan Coorg to get a little background on the design, which he says was conceived in the spirit of the 1970's BBC LS3/5A monitor speaker that used KEF drivers. He thinks the LS50 images better, is more efficient, easier to drive and it makes more bass. I owned a pair of Rogers LS3/5As back in the day, the LS50 is better in every way.

The LS50 can be used as a stand mounted hi-fi speaker or nearfield monitor, but the sound didn't fully jell in my normal desktop setup where the speakers are at ear height and 30 inches away from my ears. At that distance the LS50 was a tad bright. Don't get me wrong, it sounded better than any other speaker I've had in that position, but when I slid my chair back a foot or two the midrange filled out, and at three or four feet the sound bloomed, soundstage dimensions expanded, and the bass, mids and highs' balance smoothed out. I also pulled the LS50s off the computer and luxuriated in their sound in my hi-fi system with my mighty Pass Labs electronics and dCS Debussy digital converter. Very nice, but for this review it's all about nearfield performance.

For me the best speakers are, for lack of a better way of describing their sound, "complete," so there's less imagination required to make you feel like you're hearing live music. No speaker or headphone ever gets you all the way there, but the better ones are better because they get you closer to that ideal.

My Bel Canto REF500S, Emotiva Mini X, and my trusty old NAD 3020 amps were put into desktop service, and I was perfectly happy with the sound of all three. The REF500S' sound was high-res city, and the 3020's mellow mids proved a synergistic paring with the LS50. The Bel Canto was the one that stuck around, along with my Schiit Audio Bifrost DAC and Mac mini computer that rounded out the desktop system.

Let's play some music and see how it sounds ....

GP Acoustics (US) Ltd
10 Timber Lane
Marlboro, New Jersey 07746
732 683 2356

Bobolaclune's picture

Great review Steve - could you tell us what you were using as a Preamp ? Or did you just use the Mac Mini's volume control ?

Steve Guttenberg's picture

I used a NAD passive control with the Bel Canto amp, the others had their own controls.

Currawong's picture

...and they were fantastic. I expected the price to be much higher. They blended the best of what I liked about the Harbeths I demoed, but with a better overall balance. I fear my desk may be too small for them, however. 

Naamanf's picture

Now if you can just get a pair of the X300a to compare to....