P5 Wireless are the latest iteration of Bowers & Wilkins original P5, adding wireless functionality to this range of high-performance headphones. We talked to Steyning Research Establishment’s Head of Engineering Stuart Nevill about the continued development of Bowers & Wilkins headphones and the challenges involved in delivering True Sound to the mobile market.
The original P5 were the first Bowers & Wilkins headphone back in 2010. The headphones were greeted enthusiastically, both for their impressive sonic ability and their design and use of luxurious materials such as sheep leather. 2014 saw the launch of P5 Series 2, a serious upgrade in terms of sound quality thanks to a new drive unit technology and the growing experience and knowledge accumulated by the Bowers & Wilkins engineering team at the Steyning Research Establishment.
In 2015, P5 Wireless were Bowers & Wilkins first wireless headphone, taking the winning formula of the sound quality of P5 Series 2 and adding to it Bluetooth aptX streaming and an impressive 17-hour battery life. The result? Headphones that sound as good as P5 Series 2, but with the added convenience of seamless wireless streaming.
The original P5
Stuart Nevill explains the thinking behind the original P5 headphone, Bowers & Wilkins first attempt to deliver True Sound on the move. “We started development back in the days when the iPod started to dominate,” he recalls. “With more people than ever enjoying access to a high-quality mobile music device, it just seemed fairly obvious to us that we should try to give them the Bowers & Wilkins experience even if they were listening on the move.”
However, even with many decades of experience in developing loudspeakers behind them, headphones came with a new set of challenges including the fundamental laws of physics. “There are always factors that affect the behaviour of any audio system, but we still always aim for low distortion, low coloration, wide bandwidth and a subjectively even response,” Nevill says. “Those characteristics are consistent across all our products and across all the segments we work in. Or to put it another way, we’re looking to match the timbre of our headphones to our finest loudspeakers, as simple as that.”
“To do that, we have to be consistent. So while a few key engineers at Steyning are dedicated solely to headphone development, all the final listening work is done by the same acoustic team responsible for sign-off on all our products.”
The development of P5 Series 2
While the original P5 was successful, P5 Series 2 was the beneficiary of a serious overhaul; it retained its classy good looks, but saw the introduction of new Bowers & Wilkins headphone driver technology. Partly, these changes were down to growing experience. “When we first came to headphones we didn’t know as much as we do now!” Stuart Nevill explains. “Now we’re using a classic loudspeaker-style architecture in our headphones. The transducers we use aren’t entirely the same in approach – they’re full-range and of course, low mass is very important – but fundamentally the premise is the same.”
There are a large number of other challenges to consider as well. “Designing loudspeakers is much easier!” Nevill admits. “In most cases they don’t go anywhere and they’re certainly not picked up or worn on a regular basis. By contrast, headphones are small and of course, they’re handled all the time. That means they have to be light, robust and comfortable.
“All that means there’s a lot more to think about. We’ve effectively got a small pair of loudspeakers to deal with plus all the associated mechanical hardware needed to attach them to your head. And a good fit is vital because overall sound quality is greatly affected by the way your headphones fit to your head. On top of that, you’re also constrained by weight. With a loudspeaker, mass isn’t usually an issue. In fact, throw mass at a cabinet and it usually helps. But you can’t do that with a pair of headphones. So in essence what we’ve got to deal with is a careful balancing act between ergonomics, mass and acoustics.”
But overcome these challenges Nevill and his team most certainly did, and the results were highly impressive. P5 Series 2 – along with P7 which uses the same technology – saw a dramatic uplift in performance, with a more natural, insightful sound than what had gone before.
The next step in the evolution of the P5? The introduction of wireless streaming technology.
“The key aim is matching the sound quality; getting the performance from the wireless product as close as possible to that of the wired one,” Nevill explains. “The Bluetooth aptX codec makes a huge difference in that regard, but just as important is the presence of a dedicated headphone amplifier within the headphone itself. Bypassing the output socket on the portable device means you have more control over the signal path going into the headphone because the output impedance can be better matched to the impedance on the diaphragm. In fact, it’s better than it would be with a typical smartphone headphone output.
“We’re very proud that we managed to engineer it so that it sounds the same as the standard wired device. That’s a big achievement. Ensuring the wireless connection is robust is another big deal: don’t forget, the wireless signal is having to radiate through 50kg of water (that’s you!) to an antenna on your head. Making sure that under the best conditions it sounds the same as the wired device and that under the worst conditions it still sounds the same as the wired device – that’s the challenge and that’s what we’re proud to have overcome.”