Tower Speaker Reviews

They say a picture is worth a thousand words, but KEF's heavily illustrated instruction manual for attaching the wireless receiver modules to the surround wasn't as clear as it could have been. But after an hour or so I had the job done, though not without a minor glitch. The threaded tie-rods that hold the speaker, amp, spacer, and foot together would not tighten down completely on one of the HTS5001.2's. It felt like a stripped thread, but I could not confirm this. I tightened it as much as I dared without risk of further stripping. It was reasonably secure, but not tight enough to fully satisfy this paranoid audiophile (and no, I didn't strip the thread by aggressive tightening!).

The wireless kit also includes an RF transmitter, a special cable designed to link the transmitter to the speaker-level surround channel outputs of your AV receiver or multi-channel amp, and an additional cable that can connect the transmitter to pre-amp level outputs (included on many AVRs), or even a variable audio output straight from a CD or DVD player. There are also three "wall-wart" power supplies- one for the transmitter and one for the amp at each HTS5001.2 surround speaker.

In the review system we connected the transmitter to the speaker-level surround outputs on your receiver or multichannel amp. There they tap the signal voltage only; the transmitter draws negligible power from the surround amps.

Setting up the wireless system could not be simpler, once you get the amps attached to the bottom of each speaker. Simply aim the transmitter in the general direction of the back of the room and the speakers will receive the signal. Blue lights on the front of the transmitter and the receiver in each surround speaker/amp glow steadily when a good RF link is achieved. And since it's RF and not IR, minor obstacles appear to have no affect on the ability of the transmitter and receiver to speak to each other. Nor did I have any problem with intermittent reception. I can conceive of situations where you might, but it appears unlikely. The range of the transmitter is specified as 15 yards, so in theory, at least, you can transmit surround channels to your neighbor—though I didn't check to see how many walls the RF signal will pass through! KEF claims that microwave ovens will not affect the system, and that its 2.4MHz range is designed to avoid interference with 2.4GHz wireless phones (my wireless phone system is 5.8MHz, so I could not verify this).

In one important respect, however, the system is not wireless. Each wireless speaker requires AC to power the wireless amp. Your speakers are freed of the wired tether to your AV receiver, but not freed from the power line. The only way to do that would be to have battery-powered amps that don't have to be recharged!

KEF's wireless system has the potential, I suspect, to increase the popularity of 7.1-channel systems considerably. As mentioned, you can use more than one set of wireless systems in the same room. Each transmitter is electronically "tied" to its specific receiver so multiple 5005W systems can be used in the same system. So, for those who do want 7.1 but don't want to wire for two pairs of surround speakers, here's your answer.

RF Performance
We haven't previously reviewed the KEF KHT5005.2 speaker system—even in its fully wired form. But since the wireless operation is the big news here, I'll begin with a discussion of the wireless system and its operation, finishing up a bit further on with a report on the sound of the overall system.

The rather small speakers in this KEF system didn't appear to be candidates for my 3200 cubic foot main home theater space, so I set them up in the smaller listening room I generally use for less intense listening, TV viewing, tests of flat panel and rear projection sets and, well, all the other stuff you do in an all-purpose den. It's still a room of reasonable size, with dimensions that average 16.5' by 13' by 8.5' (just under 1800 cubic feet). It's also leaky, with open doorways to other spaces that, in effect, make it acoustically larger than an equivalent closed room would be. I drove the system with the sort of modest AV receiver that might be used often with such a system in such a room: in this case a vintage Outlaw Model 1050.

With the wireless speakers connected only as surround speakers in our 5.1-channel review system, the fine details of their performance would be masked, on most program material, by the sound from the wired front speakers. But I wanted to hear just what they were doing—good or bad. So in order to hear just the wireless HTS5001.2s, I connected them wirelessly, to the front left and right channels. There they operated, together with the wired subwoofer, as a main two-channel pair (or 2.1-channel if you want to be picky!), using conventional music CDs as a source.

They sounded impressive, though with distinct qualifications. Their limitations were such that they would not be my choice over a pair of wired HTS5001.2s as main speakers. But they never displayed any characteristics that would be distracting in a surround application. Compared to a wired pair of HTS5001.2s, they sounded a bit too warm and rich, with less clarity through the upper bass and lower midrange. The deep bass wasn't as well defined—though the subwoofer remained unchanged and the sub level was recalibrated. The top end sounded softened—though this might have simply been my reaction to the richer midbass of the wireless pair rather than an actual change in the high frequency response. The sound was "slower" overall than the wired sound, with the imaging significantly fuzzier and less precise.

Note, however, that the wireless connection is not the only change involved here. In the wired configuration the KEFs were driven by the amps in the Outlaw receiver. Wireless, the Class D amp installed in each speaker's base was driving it.

Despite these misgivings, however, I felt that the net result had more positives than negatives. It made me optimistic for the future of wireless solutions. Yes, it compromised the best sound available from the HTS5001.2s, but it did so in ways that were inoffensive. There was no edginess in the sound, no obvious distortion, and no artifacts—in short nothing to keep the surround speakers from blending seamlessly into the 5.1-channel soundstage. The lack of wires to the speakers (power cords excepted) is an obvious benefit and for many users will trump the sort of compromises I have described. In fact, you're unlikely to notice these compromises at all with much surround program material—except perhaps for the sort of surround music that positions instruments and voices all around the listener, where channel-to-channel timbre matching is most critical.

System Sound
I listened first to a wired two-channel pair of HTS5001.2s, together with the HTB2 subwoofer. I positioned the table-mount versions we received on top of 24" speaker stands to simulate the sound of the KEFs on their dedicated floor stands (which KEF did not send) as closely as possible. The subwoofer was ultimately located just behind the right front speaker. The measured in-room response showed a gradual downward slope from 200Hz-1200Hz, with the response remaining relatively uniform above that frequency until the inevitable HF rolloff, well above 10kHz. The main in-room response aberration was a deep notch at 50Hz (a characteristic of the room), though the response recovered both below this (at 40Hz) and above it (at 63Hz). I began with a crossover of 80Hz, but this was soon changed to 100Hz, which worked better in my room.

Tiny, "lifestyle" speakers are not on our usual diet here, and most of them appear designed more for aesthetics than sound. Like the bumblebee who isn't supposed to fly, such speakers are elegant to look at, but for most audiophiles a speaker with a volume of 0.05 cubic feet just can't be considered for serious listening.

But this one can. While you won't confuse its sound with the full-blooded majesty of larger, well-designed speakers, many of which KEF also makes, I was nevertheless far more impressed by the KHT 5005.2 than I expected to be.