When Sennheiser’s PXC-250 portable headphone was launched back in 2005, noise-cancelling technology was nothing new, but here was an affordable, practical and elegant implementation of it. NoiseGard™ is the name that Sennheiser gives to its particular take on noise-cancelling. Essentially, the system works by two little microphones set inside the earpieces relaying the noise they detect to an amplifier, which then inverts the phase of the signal and mixes it with the music source, which is also amplified. The result is that much of the steady state noise (hums, buzzes, droning, hissing), is removed. Ironically, because this load is taken off your ears (and brain), you suddenly become far more sensitive to other sounds out of the PXC-250’s processing band, like very low frequency vibration and high pitched rattles.
It’s easy to be cynical – the history of hi-fi wonder gadgets isn’t a happy one – but I found the PXC-250 to be an impressive package. First, even considering its hefty £90 price tag, it is impeccably built despite weighing a mere 65g. The system comes in a soft but sturdy case which is easily big enough to accommodate an MP3 walkie and a couple of memory cards too. The phones themselves fold neatly into a small, flat bundle for storage, and then unfold easily for use. They’re also very comfortable to wear, even for long periods. Still, because of their folding design, don’t expect them to have the Herculean strength of a standard pair of Sennheiser hi-fi cans.
The processor unit is a small, wand-like affair that takes the single AA battery and has a single power on-off control and a 1.8m captive cable. Put the phones over your ears, switch on and suddenly you find the PXC-250s cutting out a good proportion of the steady-state noise around you, making listening quite an eerie sensation. They don’t completely remove every bit of rattle and hum you understand, but do cut out a surprising amount of drone and general ‘whoosh’. Suddenly you can actually focus on the music, and hear quite a lot of subtle treble and midband detail too. Even powered up with no sound, the phones still cut out a lot of noise – just put them on, switch them on and hear the environment disappear!
When you do listen to music, you’ll notice some small artefacts from the system in some circumstances – sometimes there’s a slightly wobbly midband with ‘broken’ piano notes, and loss of bass power and general loss of immediacy. Still, general sound quality is good – sweet and smooth, it’s not far short of the excellent entry-level passive PX-100s. Whatever your views on signal purity, I’m in no doubt is that listening to music with a slightly ‘processed’ feel is still far more enjoyable than listening to pure, unadulterated audio complete with high levels of constant background roar. Well worth seeking out should a pair ever surface secondhand, expect to pay £30 for a really capable little headphone for music making on the move.