KEF RDM Two loudspeaker Sam's Space, October 1997
Talk about cheeky...
...the new KEF Monitor Series RDM speakers come with wood-veneered side panels called "cheeks." These are available in lacquered red, black, and charcoal, or in a natural cherrywood veneer. Beneath the veneered "cheeks" is the MDF cabinet, which is clad in gray vinyl top and bottom. The cabinet is quite dead.
The ruddy-cheeked RDM Two is particularly striking—a welcome relief from the usual boring box. These speakers will stand up and get noticed—preferably on stands 20"-24" high. The speakers are ported in the front, so they can be placed on a shelf, close to a wall (imaging and soundstaging will likely suffer, though). You can even lay these speakers on their cheeks (sides) by affixing sticky little plastic feet.
I heard the RDM Twos at HI-FI '97 while they were still being distributed by KH America, then the distributors of KEF, Celestion, and NAD. That distribution company is now defunct. KEF and Celestion are now distributed by divisions of Adcom—good news, because Adcom is one of the most widely distributed high-end brands in America (footnote 1).
The visual elegance of these speakers caught my eye, but the sound was exceptional too. I thought they'd be priced somewhere close to $2000/pair. When I heard they were $1200/pair—the price still holds with the new distributor—I asked to have a pair sent. They sent me the very same pair of speakers displayed at the Show.
Let's clear some of the basics out of the way. At 13" H by 9" W by 10" D, the RDM Two is not the smallest of minimonitors. Impedance is given as 6 ohms, and sensitivity (2.83V/1m) is stated as 90dB. The speakers are magnetically shielded. There are two sets of gold-plated speaker connectors for bi-wiring—a British article of faith.
Considering the high sensitivity, these speakers should be easy to drive. But I notice from a photograph in the product literature that the crossover, which features "audiophile grade" polypropylene capacitors in the signal path, is not exactly a minimalist job. A Conrad-Johnson MV55, rated at 45Wpc and optimized for a 5 ohm load, was up to driving the RDM Twos, but an older pair of 9Wpc Cary SE 300B triode monoblocks was definitely not—too much loss of dynamics. These speakers can use a fair ration of power—the Pass Aleph 5 was superb, and the Aleph 3 would likely be excellent too. (KEF recommends a minimum of 30Wpc. Take them at their word.)
The big deal about these speakers is KEF's so-called Uni-Q technology, which places the 1" fabric-dome tweeter bulls-eye in the center of the woofer. The idea is to avoid the phase problems that arise when there's a distance separating woofer and tweeter. The concentric driver arrangement should result in a more coherent, seamless sound—fewer phase anomalies, better focus. The 5" woofer is polypropylene with a rubber butyl rubber suspension, and the crossover frequency is 2.1kHz. The tweeter stays fixed—it doesn't wiggle when the woofer woofs.
Uni-Q makes for persuasive advertising copy and adds visual intrigue to the speaker—unless, of course, you cover the drivers with the grille cover assembly. (These speakers, like most, sound better with the grilles off.) But I've heard so many great speakers without concentric drivers—including the superb Atelier de Synergie Acoustique Baby Monitors I hope to tell you about next month—that I'm not sure that Uni-Q helps the RDM Two to "set new standards of audio clarity."
On the other hand, the concentric driver arrangement doesn't seem to hurt. The focus of these speakers is excellent—especially considering the price. The overall resolution is quite good too. When you add the fact that the speakers can play reasonably loud and fill a room with sound—the way that mini-minimonitors usually can't—you have an impressive speaker at an affordable price.
When I say "focus," by the way, I mean a combination of overall clarity and the ability of the speakers to place soloists and their instruments precisely within the soundstage—the imaging. I've heard speakers that image more uncannily than the RDM Twos, but they've usually been more expensive. And more than a few of these super-high-resolution speakers have sounds bordering on the sterile. The KEF RDM Two manages to not steer in that direction.
While I'm not sure that the RDM Two offers the ultimate resolution or the most refined harmonic presentation, you should remember that the ultimate price tag is missing too. Another thing you won't find is ultimate bass. The bass starts to roll off below 80Hz, and is pretty much gone below 60Hz. A subwoofer would be appropriate, especially in a video system.
The RDM Two doesn't seem to be voiced in the traditional BBC style of, say, the LS3/5A, the Harbeth Compact 7, and the older Spendor models and their current derivatives. I don't imagine that those who voiced this speaker spend their evenings at home listening to opera recitals or chamber music.
Interestingly for what my daughter calls old fartknockers (like me), KEF produces a version of the LS3/5A under license from the BBC. While Spendor, Harbeth, and Rogers also offer the LS3/5A, I hope Adcom decides to import KEF's version so that more customers can compare the RDM Two with this much older speaker design. I'll bet that the LS3/5A sounds somewhat polite by comparison, maybe even a little muffled. The LS3/5A will certainly sound warmer, with its elevated bass at around 80Hz. (The RDM Two sounds quite neutral.)
The RDM Two is definitely NOT an LS3/5A, nor is there any reason why it should be, especially with the LS3/5A in the KEF model line. The older speaker is exquisite. It's delicate, refined, restrained. The new speaker is altogether more outgoing, with pizzazz, focus, and clarity. The red cheeks are quite stunning—not at all garish, as you might expect, but rich-looking.
Of course, when you add a good pair of stands, you'll be looking at around $1500/pair. Still, chums, in today's market that's hardly a big chunk of change for a pair of high-end speakers. So yes, like the Mordaunt-Short 10i Pearl, the KEF RDM Two fulfilled every bit of the promise it showed at HI-FI '97.—Sam Teliig
Footnote 1: Addresses: KEF Audio (UK) Ltd., Eccleston Road, Tovil, Maidstone, Kent ME15 6QP, UK. Tel: (44) 1622-67261. Fax: (44) 1622-750653. US distributor: KEF America, Division of Adcom, 11 Elkins Road, East Brunswick, NJ 08816. Tel: (732) 390-1130. Fax: (732) 390-5657.