Speccing up a 'virtual' Jaguar XJ (ie online, and with no hope of actually getting one) a while back I noticed the most expensive option available, depending on what spec model you opt for, was the Bowers & Wilkins sound system for £1350-2000. Could a sound system really be worth that much?
To find out, I asked Stuart Nevill, principal research engineer at Bowers & Wilkins, who supply sound systems for the Jag XK, XF and XJ, about the challenges of developing the XJ’s 20-speaker, 15-channel, 1200W system. It turned out to be quite an eye-opening conversation.
“If you want the perfect sound system, then you can’t have compromises, and that's not easy in a car where there are so many other must-do requirements” he pointed out. “From our point of view that means putting the speakers in optimal, prominent locations to provide ideal sound staging, complete with large grilles that don’t obstruct the sound.”
Just how hard that is is illustrated by the fact B&W and Jaguar engineers spent four years developing the system for the XJ, and that B&W was allowed to dictate some of the XJ’s interior’s design in order to get its speakers in the correct positions.
A car has inherent compromises that must be overcome. Nevill points out that it’s no good designing a system that sounds perfect from the centre of the car – being equidistant from the speakers is normally ideal, but in a car that point is where nobody can sit – and adds that the goal is always to make the sound perfect from every seating position.
B&W overcomes this using a Audyssey MultiEQ XT calibration system, which digitally corrects any sonic imperfections created by the cabin environment by using a front-mounted microphone to detect any variants in cabin noise and then compensate for them.
The speakers are each individually designed, too. The 20 units in the XJ range in size from 25mm to 200mm, and reside everywhere from the footwells to the door pillars. Materials like Kevlar and aluminium are used in the speaker construction for much teh same reasons as they are in car construction - they are lightweight and particualrly rigid. Kevlar's uniquely constant dispersion pattern also means it delivers perfect sound across a wide range of frequencies.
If you are in the market for a premium car with premium sound system, Nevill suggests you always insist in listening to a variety of musical genres from all the seats. If the system is any good, he says, it’ll sound perfect from all of them.
Designing an in-car system isn't all hard work, though. Nevill adds that a car has basic qualities that make it an ideal place to get perfect sound quality. For instance, the volume of air the loudspeakers have to drive is constant and predictable, as are the materials used to make the car, and their positioning.
Finally, Nevill says you shouldn’t get too hung up on fiddling with the basic settings. “We set the system up to sound good whatever your preferences,” he says. “If you want more bass, treble or whatever, just add it. It won’t be to the detriment of the basic set up.”