B&W PX-7 ANC HEADPHONES

WIRELESS NOISE-CANCELLING HEADPHONES

Bowers & Wilkins, best-known for its loudspeakers, has been playing catch-up with its headphones for more than a decade. With the PX-7s, it’s finally crept ahead of the pack.

While Bowers & Wilkins has been making speakers since the 1960s, it entered the headphone market only a decade ago with the on-ear P5 Mobile Hi-Fi headphones.

The P5s strongly leveraged B&W’s reputation for luxury, all leather and shining metal, connected stethoscope-like with twisting metal rods — one reviewer back then called them “truly drop-dead gorgeous things shouting executive luxury from every curve.”

It was to be three years before B&W launched an over-ear model, a more serious headphone, again linked up with sculptural swirls of steel but — as with the P5 — there was no noise-cancelling, and no wireless operation either, depite the premium pricing.

The PX7 brings the company fully up to date with a technological full monty of wireless (or wired or USB) playback, active noise-cancellation, and app control.

THE EQUIPMENT

The B&W’s PX7 arrives at the same price as other premium wireless noise-cancellers such as the Sennheiser Momentum Wireless and Bose 700. Yet their build and construction now seems focused more on solidity than the overtly executive luxury of previous designs. The PX7 is initially available in black or grey, not the browns, golds and silvers of previous models. The cascades of steel connectors have been replaced by remarkable moulded arms made of a composite which includes carbon-fibre, yielding a slightly strange patchy matte native finish, but positively screaming strength and rigidity, while also keeping down the weight, which is 310g, not bad for a full-size headphone.

They sit comfortably over the ears for long periods — a little firm for pressure out of the box, but happy to endure a bit of stretching to the very top (non-carbon fibre) centre section in order to loosen up as you wear them.

The headshells and headband are covered in a tightly woven fabric which has a stain and moisture-repellant coating, and which can, says B&W, be cleaned by a gentle wipe or dab from a soft, damp microfibre cloth.

All in all, the effect is to make these headphones look solid and purposeful, rather than simply luxurious for the sake of it. The hard grey case is similarly practical — kept as slim as possible, and using more of that cleanable fabric wrap, mercifully free of bling.

SMARTS AND THE APP

The PX7’s smart functionality is also up with its competitors at this price-point.

Both headshells have wear sensors so that lifting an earcup will pause the music. These are headphones with a proper on/off switch, which I much prefer, but the wear sensors can also put the PX7 into standby when you take them off your head entirely, pausing media playback, disconnecting Bluetooth and switching to a low power state. When worn again, PX7 will wake and reconnect to the last-connected Bluetooth source (or two, if both are nearby and awake).

In the past I have found such auto-off functionality can get a bit annoying if it happens too quickly, but B&W’s Headphone App lets you customise how long the headphones will wait before switching to auto standby (from five minutes to an hour), or you can disable this feature entirely. Either way B&W claims 30 hours of battery power when listening via Bluetooth with ANC, after which the battery can be boosted back up quickly for an extra five hours of playback after just a 15-minute quick charge.

B&W’s Headphone App, which is clean, even basic in its design, finds and connects to the headphones, then offers three main sections: ‘Noise Control’, ‘Connections’, and ‘Settings’. But in contrast to some headphones where the app is obligatory to make many adjustments, B&W’s buttonry is comprehensive enough that you may rarely need to open the app. For example the ‘Noise Cancel’ section of the app lets you select from three NC options — low, high and auto, with a separate slider for the important option of ‘off’. But really it’s easier just to use the button on the left headshell which quickly shuttles through the NC modes. Indeed I was pleased by a small thing when pressing the NC button on the headphones — on first press it says ‘noise cancelling auto’, or whatever is the current/next setting, but thereafter

it says only one word — ‘high’, ‘low’, ‘off’, — where all other headphones I’ve tested say ‘noise cancelling high’, ‘noise cancelling low’ etc in full every time. B&W’s sensible abbreviations speed up selection considerably.

A long press of this button invokes Ambient Passthrough, which feeds through the external mikes, of which the PX7 has six — four for noise-cancelling and two for calls, these using CVC2 (Clear Voice Communication v2) to maximise call quality.

The app’s Connections setting allows you to choose two active Bluetooth connections out of the eight that can be stored; if both devices are nearby and powered up then the headphones will connect to both simultaneously, so that music started on either device will interrupt the other one from playing.

The Settings section accesses that standby timer selection to govern how long before the headphones turn off if you don’t throw the power switch, and you can also adjust the Wear Sensor sensitivity between three levels or turn the Sensors off entirely. The voice prompts can also be disabled, and you can check for software updates. That last function aside, I found the app to be pretty much set-and-forget, and the button layout so intuitive and comprehensive that I rarely opened the app.

A NEW CODEC

Still more to the point, these are the best-sounding B&W headphones I’ve yet heard, delivering a big, wide, almost open sound, assisted no doubt by the PX7’s oversize 43.7mm drivers, and a full range of Bluetooth codecs, with SBC, AAC, aptX and aptX HD, and also aptX Adaptive. This is Qualcomm’s latest Bluetooth codec which aims to deliver the higher resolution of aptX HD in a more robust way, while also incorporating the advantages of aptX Low Latency, a codec which it will apparently replace.

It is also backwards-compatible with aptX and aptX HD; indeed to enjoy aptX Adaptive’s full abilities you’ll need a phone that specifically supports aptX Adaptive — which will likely mean that unless you recently purchased a phone, you’ll need a new one. Qualcomm says that aptX Adaptive achieves its quoted 24-bit/48kHz streaming quality using remarkably low bit-rates, typically 279kbps to 420kbps, far below the actual 2304kbps of native 24/48 files. This indicated to me that, as with aptX HD, the transmission is not lossless (which I confirmed with Qualcomm). Lossless transmission can usually roughly halve a bit-rate while maintaining the file’s full integrity, so it seems that in aptX Adaptive a further lossy compression is used to drop the bit-rate to between and half and a third of that required for lossless 24/48. Of course the lossiness would be significantly less when transmitting a CD-quality file of 16-bit/44.1kHz.

Since even the quoted lower rates could cause glitches in transmission in difficult areas, the new aptX codec allows a further reduction to now happen on the fly, and this is the ‘Adaptive’ part, designed to remove the occasional glitchiness of the fixed-rate aptX HD, which runs at 576kbps when at maximum quality. “Dynamic bit-rate adaptation is designed to ensure consistently robust audio streaming in challenging RF environments, based on handset user application focus without user intervention,” says Qualcomm.

In my books that’s still significantly lossy compression, especially if the Adaptive reduction kicks in without you knowing it. The question, then, is whether you would be able to hear its effect. I couldn’t tell you, having no aptX Adaptive source, but Qualcomm offers a very interesting snippet in the form of a quote, saying “No statistically significant difference between Qualcomm aptX Adaptive at 420kbit/s and Linear Audio at 24bit / 96kHz”. The quote is attributed to “Salford University independent test results, June 2018”. So that’s Salford Uni in the UK, which has a legendary Electroacoustics department (as well as the longest bar of any UK university), claiming no measurable let alone audible difference between the best level of aptX Adaptive and the native file.

This might seem quite the claim, except that I’ve heard a very similar statement before from an equally impeccable source — Sony’s Chief Sound Architect. Using the app you can select from three levels of noise-cancelling, or turn it off using the slider. You can also do this using the buttons on the headphones. The settings menu accesses unusually versatile customisation of ‘wear sensor’ sensitivity, time to standby, and more.

He told me in a face-to-face Q&A that no-one at Sony could either hear or measure any difference between files of 256k up when played through Sony’s DSEE HX upscaling technology in comparison to a high-res version. The exceptions, he said, were dense high-information musical files, but he claimed these were rare.

Both these statements, then, point once again to the argument that high-res files are excessively large containers which are largely empty — memorably described by

The Absolute Sound’s Robert Harley as “like shipping a paperback book in a box the size of a filing cabinet”. The problem is you’re not sure exactly where the book is, so if you keep only half the filing cabinet, you might miss some important bits of the book. Most of the time, on the other hand, you’ll not notice the difference. Besides, my view is that any technology which aims to improve the quality of wireless Bluetooth transmission is to be welcomed!

Meanwhile there’s no separate listed support for aptX Low Latency, which would otherwise be of particular use for gamers on headphones, and for viewing videos with the audio played over Bluetooth, where delays can cause lip-sync issues (or sudden death for gamers!), so presumably that’s not available until you have an aptX Adaptive device in your hand.

But I used the PX7s for video watching on an iPad with absolutely no discernable lag (and with the Wear Sensors even politely pausing the video when I lifted the earcup), so no problems there anyway.

LISTENING SESSIONS

I did much of my listening using various Apple devices which, since Apple has yet to give aptX the Cupertino tick, still use the AAC codec. And the B&W PX7 shows what a well-designed wireless headphone can achieve with such an input.

Bass was rich, solid, and low — my frequency sweeps barely had time to start playing before the PX7’s bass was audibly rumbling down at and even beyond 20Hz, and I don’t recall ever hearing an entire frequency sweep sounding so perceptually flat in its delivery: no dips, no bumps. With music, one organ recording on which the bottom D is rarely delivered by headphones, was here present and only just slightly curtailed in power. The bass in the 30s of Hertz on Neil Young’s Walk With Me came through loud and huge. The synth-bass opening The Ohio Players’ fabulous Funky Worm was positively forehead-thrumming, indeed there seemed a little emphasis down low in general: the usually bass-light early 80’s recording of Colours Fly Away by The Teardrop Explodes received unusually broad bass support, which was particularly welcome on the move, though this slightly softened the track’s edginess on the heavier sections.

But it’s the overall balance which impressed me the most. Midrange and treble were both strengths, with spoken word very close to the original tone (deep male voices perhaps a little over-full), while the light and airy portrayal of higher frequency detail was a delight for the cues of jazz and classical music, with a rich yet delicate portrayal of Chick Corea’s ‘Australia’ piano concerto from its rich yet percussive piano tone to the light flute and tapping ride cymbals. Their low frequency prowess showed up my digital file of Dinah Washington’s Mad About The Boy as having something akin to turntable rumble going on underneath. Male and female vocals were tonally accurate, no thinning of male voice, no spitting or sibilance on female voice, and even the wideband vocal of Leonard Cohen was delivered as an integral image, with no smearing. So if there is a bass lift here, it’s impressively benign.

You can use a cable for playback, but it won’t save you if the PX7’s power runs out, because it needs power even to play from an analogue source. This likely explains why the sonic balance remains so similar, though that background rumble of bonus bass content disappeared when using the cable; male vocals and spoken word were lighter and things felt a little faster. But there are not the significant tonal differences common on many headphones when switching from Bluetooth to cable, including previous B&W designs.

CONCLUSION

Undoubtedly B&W’s best headphone yet, the PX7 combines high-tech design with top-notch sound (wirelessly and wired) plus delivers good (and variable!) noise-cancelling when required. There’s no EQ, even in the app (but then, they don’t need it), nor any button to invoke a smart assistant, unlike some of its rivals. But the PX7s score over such rivals in their ease of use — all the buttons clear, obvious and requiring no training, and an app which really just gets out of the way so that you can enjoy your music rather than fiddling about. I recommend them wholeheartedly. Jez Ford