The 6th generation BMW 7 Series, internal acronym (G11/G12) has been around since 2015. Now the Bavarians have renovated their flagship – but thoroughly. The update isn’t just about its martial front design with huge double kidneys and evil eyes. Apart from this retouche, which was mainly aimed at the Chinese market, there was a lot going on behind the scenes. The infotainment has undergone a thorough overhaul. This also means a noticeable increase in the performance of the optional Bowers & Wilkins Diamond Surround Sound system. The loudspeaker hardware remained the same as the pre-facelift constellation. This means an ensemble of 16 drivers of extremely high quality by car standards in the interior of the 5.12-metre-long luxury limousine.
Refined tuning of the prestigious sound system and a newly developed DSP amp result in a noticeably more harmonious, emotionally appealing sound experience for all passengers, driver included.
Bowers & Wilkins on board
Let’s first take a look at the technology behind the sound system: its most striking (and most advertised) feature is the elaborately produced tweeters, equipped with real diamond diaphragms grown under dust-free environment conditions. Being the hardest material used for loudspeakers, comparable in structure to artificial diamonds, the 1inch domes are provided with an unrivaled rigidity and internal damping. In this regard, an important technical aspect is to prevent the diaphragms from “breaking up” at high frequencies. This refers to uncontrollable partial resonances which by the use of diamond are pushed for into the HF band far from audible music.
Bowers & Wilkins is not without good reason equipping its now legendary 800-D4 series of high end home speakers with such tweeters. And as in their state-of-the-art series, the British combine the Diamond Domes with their proven Nautilus tube technology. First used in B&W’s iconic Nautilus speaker, this design serves to dampen the sound radiated from the rear of the tweeter dome. To do this, the diamond dome is taking advantage of a open tube mounted behind the magnet/tweeter unit. In it, the unwanted phase-inverted rear soundwaves are terminated by this ´acoustically indefinite´ enclosure. This ensures unparalleled treble transparency and resolution for BMW 7 Series.
However, only the three front channels (left, right, center) are taking advantage of these high-techndribers. In the fond, four 2-way systems with comparatively conventional aluminium domes are installed. After all, diamond tweeters are comparably expensive to manufacture and even in a luxurious car every cent counts.
After all, Bowers & Wilkins has put a lot of effort into the seven midrange drivers. A stiff and rigid die-cast basket instead of plastic is combined with a diaphragm made from aramid fibres providing an unmatched internal damping. Resonances within the diaphragm are stopped from exerting any distortion on the essential vocal range and thereby offering the maximum of sonic clarity.
For the diaphragms of the two woofers, B&W relies on Rohacell, a composite material that offers both maximum lightness and rigidity. The aerospace-derived material is used to give the two 22-cm subwoofers located under the front seats an unrivaled impulse response. BMW’s central bass is a groundbreaking design that uses the space of the sills as a subwoofer enclosure. This concept, patented by BMW at the time, saves space and weight – two things that developers of modern cars greatly appreciate.
As most of the technology in B&W Diamond Surround Sound system is hidden to the eyes of the beholder, a retained light show illuminates the tweeters and mid-range drivers in all four doors.
Improvement to the predecessor is even more difficult to see as the amplifier is in both cases acting as a blackbox. The 10-channel power amplifier of the predecessor is taking use of the circuitry of a classic English hi-fi amplifier. The new 16-channel Class D amplifier offering 1,375 watts RMS is somewhat more modern. The device is installed in a compartment next to the trunk under a cover.
Fully active thanks to more amplifier channels
The main difference for the audiophile performance being the higher number of channels, 16 instead of 10. So every single individual driver can be actively controlled by its own amp via a digital DSP crossover. The effect of fully active crossovers is easily audible in terms of better sonic midrange integration. The Harman engineers responsible for the Diamond Surround Sound system, as for all Bowers & Wilkins automotive applications, were thereby able to take use of a steeper filter for the 10-cm midrange drivers in the doors offering a lower crossover frequency. This is not just preventing acoustical overloading of the drivers but also rattling of nearby metal parts.
After all, every system design is preceded by a spectral analysis of its body structure and interior trim. Steep slopes typically made possible by digital crossovers are expanding the usable range of every single. To some extent the maturation of the BMW 7 Series, which has already been in production for four years, had a positive effect on the set-up. As far as performance under driving conditions is concerned, however, quite different measures have an extremely positive effect. The technical update also went deep into the electronics.
A music Lounge on wheels
The rolling noise audible in the rear has been effectively reduced by optimised shielding of the rear wheel arches. In the area of the B-pillar, as well as at the belt exits and the seat backrest in the rear, optimised sound insulation elements ensure a further reduction on the noisefloor. In addition to the windscreen, the side windows and rear window are now also made of laminated glass with a thickness increased to 5.1 millimetres – this is standard for the BMW 750i xDrive, BMW 750Li xDrive and BMW M760Li xDrive. For all other variants, it is part of the rear comfort glass option (1300 euros), with which our test sample was equipped. In addition, optimized engine mounts for the diesel drives increase comfort by lowering vibrations.
The result is such a quiet, vibration-free driving experience that in the BMW 750d xDrive gives despite its 400 hp direct-injection diesel the pure impression of driving an electric vehicule. In fact, the wind and rolling noise are so low that most e-vehicles actually would lose any challenge. In short: The Bavarians provide an advantage for the British, who, despite the standard-setting low noise level, still adjust their dynamic equalizer to the respective noise level in real time via built-in microphones.
BMW takes the BUS
To be complete, we should also mention particular technologies of which the user is not aware. Mainly for economical reasons, BMW has now dispensed with the usual digital-optical fiber-optic connections for the MOST bus (Media Oriented Systems Transport) in the 7 Series. For distributing infotainment data, the Bavarians rely on the common Ethernet offering 100Mbps. Because audio and video data are always time-critical, the use of the AVB standard (Audio Video Bridging), which was originally developed for live video streaming, and ensures delay-free playback.
Finally, Ethernet is based on a stochastic access method with limited real-time capability. Thanks to AVB, however, the BMW 7 Series is capable of lip-synchronous playback of video images and the corresponding audio track. Finally, the optional rear seat entertainment brings with it two flat screens on the backs of the front seats. Of course, with its optional rear-seat entertainment, the 7 Series can also play Blu-rays and reproduce multi-channel sound in all its glory via B&W speakers.
In contrast, moving the audio tuner section for FM and DAB+ from the head unit to the new DSP output stage was almost trivial.
In order to provide the necessary computing power for the state-of-the-art infotainment, which can also be controlled via an Android tablet docked on the centre console, BMW switched to a processor from Intel’s Apollo Lake platform. This means, the system is equipped with four cores clocked at 1.9 GHz in the head unit. And that is provided with 6 GB RAM in conjunction with a 320 GB hard disk.
Thanks to the powerful Intel processor, the 7 Series test car manages the feat of perceiving the voice command to wake the new BMW Intelligent Personal Assistant even while playing music at high volume. This is less due to the microphones than to the strategy in the background. The Bavarians can use the ample computing power of their DSP to simply calculate the music signal known to the system from the microphone recording in the head unit. What remains is pure voice information, with which the digital servant fulfils requests for display of the weather map or for freely spoken destination input for the navigation system without any hand movement on the part of the user.
A separate report could be written about the cockpit, which is connected to the internet via Connected Drive, with its displays no longer designed as a PlayStation copy of analogue instruments. Just this much: BMW is also taking a big step in the right direction here.
Matured over the years
The combined driving and listening test proves already on the first kilometers: BMW and B&W have made a very good thing even better. The almost inimitable way of moving about, bedded down on air suspension and comfort seats upholstered in the finest leather, is perfectly rounded off by the Diamond Surround Sound System, which is much finer and more substantial than before. With the same effortlessness and vehemence with which the quadruple turbocharged in-line six-cylinder turbo unit floats towards the horizon with its 760 Newton metres of torque from 2000 to 3000 rpm like a flying carpet with warp drive, the B&W sound system provides the interior with gripping music reproduction.
The songs may be streamed to the head unit via Bluetooth with ACC direct transmission for iPhones. They can also come in high resolution from the integrated hard disk or a USB stick. The sound is always great cinema. During the update, B&W also renovated the five sound presets (Studio, Concert, On-Stage, Cinema, Lounge), which allow owners to customize the sound of their high-end system to their own tastes. The basis for the sound programs is the Quantum Logic process contributed by Harman, which Ferrari also uses in the JBL sound systems.
It is particularly noticeable that under the direction of Philipp Göppl, Principal Acoustic Systems Engineer at Harman, the ultra-direct reproduction in studio mode has been designed to be a little less harsh and a little more spatial.
Regardless of these taste-dependent presets, the midrange drivers now seem better integrated into the sound image. The extremely high-resolution trebles no longer seem so forced, and the more substantial fundamental range is particularly convincing, making voices and instruments seem warmer and more full-bodied. As a result, the new Bowers & Wilkins Diamond surround sound system no longer reacts harshly to certain recordings.
BMW 7 Series with Bowers & Wilkins Diamond Surround
There was already nothing to criticize on the bass of the predecessor. Along with the outstanding diamond tweeters, it was without any doubt the flagship of B&W’s previous system. Bass nots don’t come out of the speakers quite as crisp, ultimately dry and perfectly contoured. On the other hand, the overall tonal balance seems to be a bit more voluminous and more pleasing. Music in the new BMW 7 Series is simply touching your heart while the predecessor merely adressed the mind of a recording engineer.
If you prefer such studiomonitor-like performance, the sound mode of your choice in the B&W controls is called “Studio”, especially on the front seats. This allows B&W to demonstrate its unrivalled position for precision, transparency and sonic resolution. If you prefer a wider stage imaging and don’t want to feel like you’re in a recording studio with near-field monitors, you’ll get a hell of a party with other modes offering a wide panorama and particularly full-bodied sound – even on the rear seats. In general, a lot has been done in the back, where you can even enjoy a particularly spacious panorama. This finally turns the BMW 7 Series into a flying concert hall.
- Price BMW 7 Series: from around 92,000 euros
- Price B&W Diamond Surround Sound System: 5,850 euros
- For more information: www.bmw.com
Stereo Guide verdict
+ Highly natural tonal balance
+ extremely fine resolution
+ High dynamic reserves and max SPL
+ Excellent infotainment operation
+ Air suspension with active rear axle steering combines comfort with sportiness
- precision of tight bass impulses suffered as mid-high range got faster
Price/Performance sound system9.2