KEF Universal Wireless System review: KEF Universal Wireless System

Wireless speakers are a great concept--get rid of those nasty wires and place your speakers wherever you want. Then reality sets in: wireless speakers still need power, so they need to be tethered to a wall outlet. And if the speakers don't have a wireless receiver built-in, they need wires connecting them to one. And, typically, their sound quality ranged from barely acceptable to pretty awful. Then again, we're most accustomed to hearing the proprietary wireless speakers that come with home-theater-in-a-box systems, so the speakers themselves aren't all that great to begin with. What if somebody offered a wireless system you could use with speakers of your choice? Such products are finally starting to appear, with the Rocketfish Universal Wireless Rear Speaker Kit at the entry-level side of the market, and KEF's Universal Wireless System (reviewed here) at the top. Both use 2.4GHz radio signals to link the rear speakers of a 5.1 surround system to the wireless transmitter attached to the amplifier at the front of the room--eliminating the need to run the longest speaker cables to the back of the room, while the front left, center, and right speakers remain wired up. But unlike a lot of two-part wireless systems, where the rear receiver needs to be wired to speakers at each end of the room, the KEF Wireless System has two separate receivers--one for each speaker--so the connecting cables can be very short. The bigger advantage--and what you're really paying $600 for--is the sound quality. While the "CD-quality" description is thrown around quite a bit these days, it's safe to say that KEF comes closer to delivering on that claim than any other wireless speaker system to date.

Design and setup
The KEF Universal Wireless System is basically a three-part system: one transmitter plus two receivers. All three units are vertically oriented black slabs about 6 inches tall, each with a circular plastic base. Each module also needs its own AC power supply, and the kit includes the necessary interconnects to wire each receiver to its matching speaker, and the transmitter to the audio source.

Like all "wireless" speaker systems, the KEF package includes quite a few wires.

Once you've identified which of the two different types of power supplies gets plugged into the transmitter and receivers, setup is piece of cake. Oh, there was one other little catch; at first we couldn't tell the difference between the left- and right-channel receiver modules. Turns out they are clearly marked, but it's on the undersides of their bases.

No special care is required when positioning the receiver modules and transmitter. Just connect the 5-foot-long speaker cable that comes with the KEF Wireless Transmitter to your AV receiver, plug the transmitter and two receiver modules' power supplies into AC outlets, and hook up wires between the receiver modules and your speakers. Seconds after you power up the transmitter and receiver modules, they will automatically locate each other, their flashing blue indicator lights will stop flashing, and you're good to go.

Features
KEF claims to have developed the system's 2.4GHz wireless, HFADPCM (high-fidelity adaptive differential pulse code modulation) transmission technology with error-protection and sophisticated adaptive frequency hopping to ensure an interference-free signal. This proprietary technology is designed to change channels automatically before any errors are audible. As such, the intention is to deliver CD-quality audio that won't be affected by microwave ovens, cordless phones, or LAN routers, all of which operate on the same frequency.

Each receiver module houses a 50-watt digital amplifier to power the speaker. Speaker cables can be connected with banana jacks, spades, or bare wire ends. So as long as your speakers have standard terminals, you're good to go. Kudos to KEF for going with standardized connectors and eschewing any proprietary nonsense. (If, on the other hand, your speakers utilize proprietary connectors--such as those found on many home-theater-in-a-box systems--you'll probably need to hunt down the manufacturer's own wireless system. Most mainstream manufacturers--including Sony, Panasonic, Samsung, and LG--now offer wireless rear speaker kits, or bundle them with the systems to begin with.)

The receivers (left and right) and transmitter (center) should work with any standard speaker and audio system.

The transmitter includes a special cable that plugs into your AV receiver or amplifier--it's labeled clearly and should connect to any spring-clip or binding post found on the back panel of any stereo or surround system. The transmitter can also directly accept a stereo 3.5mm plug, which we alternatively used to hook up an iPod. We used the iPod volume control to adjust the volume of the sound of the speakers being fed by the KEF Wireless System.

A third hookup possibility involves using the KEF Universal Wireless System to power speakers in another room of your house or apartment--perfect for utilizing a "zone 2" feature of your AV receiver without stringing wires through the wall. KEF doesn't specify a maximum range for transmission, but it worked perfectly well in a room we tried that was about 25 feet from the transmitter.

As far as competition is concerned, aside from the aforementioned RocketFish Wireless Kit--which is far cheaper--anyone looking for just a pair of stereo speakers should consider the JBL OnAir Control 2.4G, which retails for $350. Furthermore, anyone considering KEF's excellent KHT 5005.2 speaker system will want to investigate the matching KHT 5005.2W Wireless Kit. It's essentially a version of the Universal Wireless System that's made to exactly match the rear speakers of the KHT 5005.2 system. The receivers attach directly to the rear speakers and are integrated right into the stands--only the AC power cord for each rear speaker is necessary.

Performance
Once we had the KEF system up and running, everything worked perfectly right off the bat--no need for the sort of time-consuming setup process that we're used to with a Wi-Fi network. We noted the system was quiet--there was absolutely no hiss or whistling tones emitted by the speakers. Only occasional pops were noticeable, but they were barely audible. We were intently listening for digital artifacts, and the pops didn't interfere with our enjoyment of music or home theater.

The KEF wireless receiver, connected to a typical surround speaker (as seen from the back).

Sound quality claims are easy to make, but every other wireless system we've tested to date has been permanently mated to HTIB speakers, so we could never verify the claims. The KEF Universal Wireless System is the first we've tried that can be used with any speaker. True, its prime mission is to serve as a wireless connection for surround speakers in home theater systems, but we decided to first test the KEF Wireless system with high quality Dynaudio Contour 1.1 speakers, as "front" speakers in stereo. The sound was excellent, with good, solid bass, natural midrange, and clear treble. There were only the most minimal of processing artifacts (the very mild popping sounds we mentioned earlier), and most of the time, we never heard any pops. Stereo separation was first-rate.

We next used the KEF system with the Dynaudio speakers as surround speakers in our all-Dynaudio system. The wireless sound was so good, we quickly forgot the surround speakers weren't hooked up with wires (and used that way, we never heard the popping sounds). Yes, KEF is charging a high premium for its wireless kit, but that's because it delivers the goods. If you're looking for no-compromise wireless, the KEF Wireless System is highly recommended.