Meridian in-car audio
Ground-breaking digital in-car
entertainment system, customdesigned for the 12C
2.2 stereo and 5.2 surround-sound
Digital Active loudspeaker system
featuring Meridian DSP Loudspeaker
High sound output level with minimal
Full frequency range with deep bass
Advanced DSP technology
automatically adjusts audio settings
to compensate for environmental
The Meridian Advantage
Conventional consumer audio systems,
whether in-home or in-car, have followed
a traditional pattern in which the power
amplifiers supply a full-range audio signal to
the loudspeakers, where a passive crossover
divides the signal into frequency bands to be
supplied to woofer and tweeter.
This approach requires a number of
significant compromises in the design of the
system, including the need for excessively
large power amplifiers to overcome the
low efficiency of passive systems, and the
need for the passive crossover to employ
components chosen for their power-handling
capacity rather than their audio quality.
Thirty years ago, Meridian’s founders
turned their back on convention and
instead developed some of the first active
loudspeakers available, going on to use
digital signal processing (DSP) to create
crossovers that would be impossible in the
analogue domain, and becoming the first
consumer audio manufacturer to do so.
Meridian DSP-based digital active
loudspeakers use a fully-digital crossover
followed by digital to analogue converters
(DACs) to drive individual amplifiers which
power the loudspeaker drivers directly,
maximising efficiency and allowing a level
of performance usually associated with
loudspeakers at least four times the size.
Meridian’s successful application of digital
audio technology in its award-winning luxury
home entertainment systems made it an
obvious choice when McLaren Automotive
came to specify a custom audio system for
their new 12C high performance sports car,
from the home of the world’s most successful
racing car company, where revolutionary
engineering and an absolute focus on
efficiency are second nature.
Exceptionally high efficiency, powerto-weight ratio and compact size
Standard components and
interconnects shared between 2.2 and
Fine-tuned DSP to match vehicle
interior acoustic space
Meridian was commissioned to develop
two different systems, one stereo and one
surround. Both deliver high sound output
levels with minimal distortion; a balanced,
extended frequency response; plus minimum
weight and package size. The two systems
share common hardware and interconnects
as much as possible and feature common
door-mounted sealed loudspeaker
enclosures for (front) left and right.
Meridian’s DSP Digital Active approach
to audio systems design is particularly
appropriate in a luxury sports vehicle, where
it is important to maximise performance
while minimising the size and weight of the
installation. In this case, the DSP approach
Meridian Audio Limited
Meridian in-car audio
adjust the frequency balance of the system to
suit their taste.
The Dynamic Range Control system offers a
comprehensive method of ensuring that the
listening experience is maintained whatever
the environmental conditions. A wide range
of environmental signals is received by the
unit, for example the fact that a window is
open, and the speed of travel. This data is
comprehensively and continually analysed to
allow the system to compensate automatically
for variations in such factors as ambient
noise, so as to maintain a consistent level of
perceived audio performance irrespective of
allows the maximum performance to be
developed from smaller, lighter loudspeaker
assemblies. DSP active crossover technology
also dispenses with heavy, bulky conventional
crossover components while at the same time
dramatically increasing audio performance,
while permitting the use of smaller, more
efficient and lighter amplification. The use
of Class D amplification delivers maximum
power in a very compact and lightweight
package, without the slightest compromise in
The unique Meridian DSP-based approach
delivers a whole new level of performance
and excitement to high-quality stereo
and surround audio in the luxury highperformance sports vehicle market.
The two systems created for the 12C provide
stereo and surround capability. In the case
of the stereo system, two door-mounted
loudspeaker installations are employed, left
and right. In the case of the surround system,
these are augmented with three additional
The door-mounted assemblies (see below)
include both bass and full-range drivers,
which are driven by independent amplifier
channels. The bass drivers in the doors
provide the bass for the entire system,
whether stereo or surround: thus the system
can be described as either 2.2 (stereo) or
5.2 (surround). Each driver is energised
by its own super-efficient Class D power
amplifier fed by individual location-specific
equalisation and delay algorithms.
The amplifier/DSP unit
Amplification and DSP capability are
contained in a digital amplifier unit, which
is supplied from the system’s head-end
source unit with either two or six channels
of digital audio at up to 96kHz sample rate,
plus RS232 control data, via a single RJ45
connector. The amplifier unit has a DC
power connector and a 16-pin connector for
analogue audio output to the loudspeakers.
It includes either four (2.2) or seven (5.2)
channels of Class D amplification, depending
on the system, each channel delivering in
excess of 40W into 4Ω.
The Automatic Volume Control function
adjusts the volume of the sound system to
compensate for estimated engine, road (tyre)
and wind noise. There are three settings for
AVC: Off, Min and Max. ‘Off’ disables the AVC
function and the volume remains constant at
the user-selected level regardless of vehicle
speed. ‘Min’ is the lowest setting of the AVC
system: the volume adapts gently to vehicle
speed and other parameters. This mode has
been calibrated for smooth road surfaces.
‘Max’ is the highest setting. Here, the volume
adapts more aggressively to changes in
vehicle speed and other parameters. This
mode has been calibrated for rougher road
The AVC also raises the volume when the
engine is started, and compensates for a
The amplifier unit also contains the system’s
DSP (Digital Signal Processing) capability in
the form of a 200MHz dual core processor
delivering 400 MIPS (million instructions per
second). The DSP in the amplifier unit carries
out a series of functions:
• System Volume
• Bass, Treble and Balance controls
• Rear Gain Control (Hi-Line system)
• Dynamic Range Control
• Automatic Volume Control (AVC)
• Automatic Tone Control (ATC)
• Loudness filtering
• Channel format conversion
(including re-matrixing and stereo
width, and converting 2-channel input
to 5.2 and 5.1 input to 2.2)
• Crossovers and bass management
• Driver equalisation
• Limiters and delay
The bass, treble, balance and rear gain
controls provide the user with the ability to
Main drivers in sealed enclosure
Meridian in-car audio
lowered window by raising the volume on that
side of the vehicle. The volume correction
for the window function is road-speed
In Normal and Winter powertrain modes,
the AVC operates with road speed and
rpm. In Sport and Track powertrain modes,
the AVC also uses throttle position to add
compensation for the increased engine noise
generated by the ISG. The correction curves
for road speed and rpm are also slightly more
aggressive to compensate for the additional
noise and to add further aural excitement to
these powertrain modes.
The Automatic Tone Control (selectable On/
Off) boosts the bass when the engine is
started to compensate for the masking effect
of the low frequency noise of the engine.
Both bass and treble are automatically
adjusted with road speed to compensate for
road and wind noise.
165mm LF Driver
Power Handling RMS:
Power Handling max:
Operating Frequency Range:
20 Hz – 2 kHz
THD @ 10W:
< 5% from 20Hz – 60 Hz (IEC 268-5)
< 2% from 60Hz – 140 Hz (IEC 268-5)
< 1% from 140Hz – 2 kHz (IEC 268-5)
Chassis OD (max.):
600g (± 5g)
Voice Coil Former:
Polyamide / Fibreglass
Magnet Material: NdFeB (N40H)/Fb2 (Y35)
85mm Full-Range Driver
Power Handling RMS:
Power Handling max:
Operating Frequency Range: 100 Hz – 20 kHz
More aggressive correction is applied when
the powertrain mode is set to Sport or Track.
Loudness Filtering allows the system to
compensate for human hearing’s reduced
sensitivity to low and high frequencies at
lower sound pressure levels, boosting these
frequencies according to specially-developed
filter curve characteristics that are modelled
on psychoacoustic research. The Loudness
Filtering technology builds on developments
first employed in Meridian’s F80, a luxury allin-one entertainment system, which is very
highly regarded for its audio performance
and loudness compensation.
The system head unit provided in the vehicle
is able to deliver both stereo (2-channel)
and multichannel surround (5.1-channel)
signals. These signals are re-matrixed by
comprehensive algorithms designed to
‘render’ the incoming audio signal to suit the
in-car installation exactly, while at the same
time providing bass management functions
THD @ 10W:
Chassis OD (max.):
225g (± 5g)
Voice Coil Former Material:
Loudspeaker Door Assemblies
75% ABS / 25% PC
4-part assembly –
L & R assemblies.
Acoustic polyester fibre &
mechanical silicone rubber motor damper.
Drive Unit Configuration:
1 x 165mm LF
1 x 85mm full range.
audio input connector.
DSP – Frequency 200Hz.
optimised for speaker.
to ensure that bass signals from any channel
are fed to the bass drivers on the correct side
of the vehicle, maintaining spatial accuracy
across the entire frequency range.
In the case of a 2.2-channel in-car
installation, stereo source material is passed
through a user-variable stereo-widening
system based on that used in the Meridian
M80. Bass information from left and right is
separated to drive the bass units while the
full-range drivers receive the mid and high
frequencies, their locations optimised to
deliver precise imaging and sonic accuracy.
Surround (5.1) source material is downmixed
to drive the 2.2 output configuration,
employing Meridian’s unique psychoacoustic
technologies to deliver the best possible
spatial experience even though only two
output channels are involved.
In the case of the 5.2 surround in-car
installation, 2-channel stereo material is
Terminal Layout: 8-way RJ-45 digital S/PDIF
6 channel input connector,
2-way power connector,
16-way analogue audio out connector.
5-36V DC in.
DC-DC PWM power supply.
Power Supply Design:
6 layer PCB.
Current Protection: Over-current, over-voltage
transient, reverse polarity and thermal.
Class D with feedback.
4 or 7.
RMS Power Rating: 4/7x > 40W/ch into 4 Ω.
Crossover: DSP optimisation in digital domain.
Frequency Response: Each channel optimised
Signal to Noise:
Better than –100dBFS.
DSP Devices: 200MHz Dual Core (400 MIPS).
232 mm x 61 mm x 225 mm.
1.35 Kg (5.2 version)
1.28 Kg (2.2 version)
Meridian in-car audio
Left: 165mm driver; right: 85mm driver (not to scale)
passed through an enhanced multichannel
matrix. This dramatically increases the
naturalness of stereo listening by using
the three front loudspeakers to render
stereo material with significantly increased
localisational accuracy. At the same time,
depth information, latent in many types of
stereo recording, is extracted and fed to the
rear channels, delivering an uncanny sense
of presence and realism in surround, despite
the source material being stereo only.
5.1 surround source material is enhanced for
the 5.2 replay system via a comprehensive
bass management strategy that enhances
surround immersion and overall performance.
whether you prefer soothing classical music,
club dance or heavy metal at full volume. The
same system protects your audio investment
against overheating, overload and distortion.
The DSP system continually monitors
the performance and behaviour of all
the loudspeaker drivers. As a result,
it can instantaneously correct system
characteristics to maintain optimum
performance under all operating conditions,
Each loudspeaker is driven by a carefullycalculated delay algorithm that ensures that
audio reaching your ears is timed exactly for
maximum realism and precision, delivering
the very best, most natural performance.
In all configurations, whatever the source
material, the DSP-based crossover and
bass management system ensures
maximum performance and sonic accuracy
are delivered at all times. The drivers are
individually digitally equalised according to
their location and enclosure characteristics,
to create a completely integrated replay
system in which all the loudspeakers work
together to fill the in-car environment with
pure, natural, digital sound, exactly tailored
for the unique acoustic environment of the
The two primary loudspeaker enclosure
assemblies are the same in both systems,
and consist of a 165mm (6.5in) low
frequency drive unit (illustrated above
left) and an 85mm (3.5in) full range driver
(illustrated above right: not to scale) installed
in sealed enclosures, which are doormounted. The low frequency drive units
carry the bass signals for the entire system.
These two units comprise the loudspeaker
assemblies for the stereo (2.2) system.
Exploded view of the amplifier/DSP unit
In the case of the surround (5.2) system,
these units are augmented by three
additional 85mm full-range drivers (illustrated
above), one mounted in the fascia and two
behind the seats, left and right.
M12CDS v1.3• 20120719 REƒ