We have been waiting for Kleer Audio Technology to appear in home headphones and are thrilled that Sennheiser has led the way.

Wireless headphones are nothing new. For many years there have been battery-powered headphones available, receiving from transmitter units that connect to a headphone socket or hi-fi amplifier.

Freedom of movement? Yes. An end to standing up and yanking out the headphone cable painfully? Yes. Hi-fi heaven? ’Fraid not.


The audio quality, even from respectable brands, was always poor, because the transmission was performed in analogue, via FM on the vast majority of wireless headphones. (A rare few used infrared; more recently there has been Bluetooth.) FM transmission inevitably resulted in high hiss levels, usually fizzing and fading as you moved around. It was your classic compromise — drop the cable, and you also dropped audio quality.

No longer. The hero of this story is Kleer wireless audio technology, the creators of which have just passed into the orbit of SMSC in New York, a company perhaps best known for its automotive networking platform, MOST.

We have seen Kleer in a couple of products before — in Sennheiser’s pricey MX W1 wireless earbuds, and in the DigifiOpera S5 earphones last issue. Both were designed for the portable headphone market, aiming to break the link between iPod (other portable media players are available) and earphone. Even though this left the Sennheisers free to fall on the floor if they slipped out.


But we have been waiting for Kleer to appear in home headphones, and are thrilled that Sennheiser has led the way. Three models have been launched recently — the $350 RS 160, $450 RS 170 and $550 RS 180. We heartily recommend them all. Even the lowest of them are high quality Sennheisers (although of course there’s no way to judge the actual headphones independent of the transmission). We found them to have a slightly more ‘closed’ feel than comparable Sennheiser wired headphones, just slightly thicker, but really, only slightly. As you go up the model list, you get improved transducers and more range; the top two have a stand-up transmitter that also charges the headphones when not in use, whereas the RS 160 transmitter is a puck-shaped unit with a flying lead to charge the headphones. All use supplied AAA rechargeable batteries.

And all of them are complete game changers for anyone doing a lot of home headphone listening. In a word, they bring freedom. You can listen in other rooms, sit out on the deck, dance around. You can go to the loo while still humming away. We spent an hour shredding foliage in the garden while streaming a podcast to the RS 180s, until our sweating head put the soft ear-cups in danger of over-soakage.


Remarkably for Sennheiser, there are a couple of schoolboy errors. The control buttons on the right earpiece are dreadfully designed. With the power button between the two volume buttons, it’s easy to power down instead of turning them down, and heaven forbid you should press the ‘balance’ buttons on the RS 180s, because there’s no obvious way to re-establish their centre position. (Why balance controls anyway? For people with asymmetric hearing loss?) The HD 170s add a bass boost and a dreadful ‘surround’ effect, which throws things so horribly out of phase it’ll make any studio engineer feel positively sick. The HD 180s have an ‘ALC’ limiter so that if you overcrank the input signal, it crackles momentarily then backs off automatically, slowly ramping back up as if under some automated digital control. The ALC is supposed to be defeatable, but on our sample the off position merely reduced the effect, it didn’t remove it. Not very hi-fi.

Our wishlist for Gen 2 would also include a digital input, even a USB connection, so that a digital source could be converted straight to Kleer format for ongoing transmission. As it is, there’s a redundant stage of digitisation going on — from (probably digital) source to the transmitter’s analogue inputs and back to digital for transmission to headphones.

Don’t let this put you off. These are magnificent products, beautifully made, extremely comfortable and sounding great. They change the whole home headphone game. Freedom at last!

Distributor: Syntec International Pty Ltd