Review: KEF LS50 speaker
KEF made the LS50 minispeaker for lots of reasons. It’s a celebration of the company’s 50th anniversary. It’s the first affordable application of the technology developed for the $29,999/pair Blade. It’s a throwback to the LS3/5a, a beloved, BBC-designed minimonitor for which KEF made the drivers.
At $1,499/pair, the LS50 isn’t cheap, but KEF designed it as a true reference-grade speaker. That phrase, twisted to near meaninglessness by cynical marketers, is supposed to refer to a product against which others can be judged.
The LS50 certainly seems to have the goods. Its ultra-rigid, dense, heavily braced, compact enclosure is designed so it doesn’t mar your music with extraneous vibration or resonance. The curved front baffle not only looks cool, it also minimizes reflection of sounds (or diffraction) from the front of the speaker. The coaxial driver assembly, heavily influenced by the Blade’s drivers, puts the tweeter inside the woofer so all frequencies of sound emerge from the same source, and the drivers can’t interfere with each other. The oval port is shaped to minimize turbulence and prevent nasty “chuffing” sounds as the air moves in and out. (Weirdly, the inside of the port is made from soft, pliable material instead of hard plastic.)
After hearing the LS50 do its thing at the Rocky Mountain Audio Fest, I couldn’t wait to give it a spin in my own listening room. I placed the pair of speakers atop my kitty-litter-filled Target stands, powered them with a Krell S-300i integrated amp, and used my Pro-Ject RM-1.3 turntable and Firestone Audio I?TW USB DAC as sources. A little experimentation told me that the LS50 is not at all fussy about positioning; I ended up toeing the speakers in to point straight at my head, but they didn’t sound all that different when I pointed them straight out.
A real reference?
I’ve been reviewing speakers since 1991, and measuring them since 1997. In all that time, I’ve found that for me, the most important element of speaker design is the crossover between the midrange (or midrange/woofer) driver and the tweeter. I can’t help but focusing on the crossover when I listen to a speaker. The common problems of a poorly implemented crossover—narrowing dispersion in the midwoofer, “cupped hands” coloration, and tweeter distortion—drive me nuts.
The LS50 is the first speaker I’ve reviewed where I couldn’t hear the crossover. Or to put it differently, the crossover region—i.e., the midrange between roughly 1 to 4 kHz—sounded so clean and natural to me that I almost didn’t know what to think of this speaker.
When I played Steely Dan’s “Aja,” one of my all-around, go-to cuts for speaker evaluation, the midrange sounded cleaner than I could ever remember hearing in years of listening to this tune. Donald Fagen’s reedy, tough-to-reproduce voice sounded incredibly natural and lifelike, perfectly imaged in space between the two speakers. The melodic bass line sounded totally tuneful and sweetly satisfying; my soul held not the slightest desire to add a subwoofer.
One of the best (although sadly, one of the most obscure) recordings in my collection is the rendition of “I Only Have Eyes for You” by the late avant-jazz trumpeter Lester Bowie and his horns-plus-drums band Brass Fantasy. It’s recorded in some sort of large space that sounds deliciously reverberant, but all that reverb often obscures the sonic images. Not with the LS50, though. For the first time I can remember in almost 20 years of testing speakers with this track, I heard specific sonic images of each horn in Bowie’s group.
Another tough-to-reproduce cut in my collection—one that the president of an audio technology company recently told me was “unfair”—is “Shower the People,” from James Taylor’s Live at the Beacon Theatre. (I listen to a copy of the PCM stereo track from the DVD.) Most speakers color and distort Taylor’s voice and acoustic guitar in rather obvious ways, but not the LS50. Not only did the guitar and voice sound pretty much perfect—yeah, I said “perfect”—the bass sounded simultaneously powerful and tuneful, and the super-high-pitched glockenspiel notes rang out cleanly.
My favorite new testing track is “Four Women,” Meshell Ndegeocello’s moving rendition of a Nina Simone tune I’d previously considered somewhat hokey. The LS50 imaged Ndegeocello’s voice between the speakers in a way that was so haunting, with so much emotional impact, that it was hard not to cry when I heard it. Chris Bruce’s electric guitar sounded so real, so perfectly embodied, that it felt like his Fender amp was right in the room with me.
Although I didn’t have a quintet of LS50s so I could put together a 5.1 system for home theater, I did play the excellent Willem Dafoe drama The Hunter through them just to see how they’d handle film sound. Even without a subwoofer, the LS50 delivered plenty of impact during The Hunter’s tensest sequences, in which low-frequency tones swelled portentously.
Is the LS50 perfect? Nope. No speaker is. As with other Uni-Q designs I’ve heard, even though it images with great precision, it doesn’t create a huge, enveloping soundstage, and the sound doesn’t stretch far beyond the outer edges of the speakers. The bass is excellent for a small speaker, but if you want to crank the hell out of it you should add a sub. Mötley Crüe’s “Kickstart My Heart” sounded clean at 93 dB (measured from my listening position about 10 feet away), but a little thin.