McLaren 12C Meridian in-car audio System Highlights Ground-breaking digital in-car entertainment system, custom- designed for the 12C 2.2 stereo and 5.2 surround-sound models Digital Active loudspeaker system featuring Meridian DSP Loudspeaker technology High sound output level with minimal distortion Full frequency range with deep bass extension Advanced DSP technology automatically adjusts audio settings to compensate for environmental sounds Exceptionally high efficiency, power- to-weight ratio and compact size The Meridian Advantage maximising efficiency and allowing a level Conventional consumer audio systems, of performance usually associated with Standard components and whether in-home or in-car, have followed loudspeakers at least four times the size. interconnects shared between 2.2 and a traditional pattern in which the power 5.2 systems amplifiers supply a full-range audio signal to Meridian’s successful application of digital Fine-tuned DSP to match vehicle the loudspeakers, where a passive crossover audio technology in its award-winning luxury interior acoustic space divides the signal into frequency bands to be home entertainment systems made it an supplied to woofer and tweeter. obvious choice when McLaren Automotive came to specify a custom audio system for This approach requires a number of their new 12C high performance sports car, significant compromises in the design of the from the home of the world’s most successful system, including the need for excessively racing car company, where revolutionary large power amplifiers to overcome the engineering and an absolute focus on low efficiency of passive systems, and the efficiency are second nature. need for the passive crossover to employ components chosen for their power-handling Meridian was commissioned to develop capacity rather than their audio quality. two different systems, one stereo and one surround. Both deliver high sound output Thirty years ago, Meridian’s founders levels with minimal distortion; a balanced, turned their back on convention and extended frequency response; plus minimum instead developed some of the first active weight and package size. The two systems loudspeakers available, going on to use share common hardware and interconnects digital signal processing (DSP) to create as much as possible and feature common crossovers that would be impossible in the door-mounted sealed loudspeaker analogue domain, and becoming the first enclosures for (front) left and right. consumer audio manufacturer to do so. Meridian’s DSP Digital Active approach Meridian DSP-based digital active to audio systems design is particularly loudspeakers use a fully-digital crossover appropriate in a luxury sports vehicle, where followed by digital to analogue converters it is important to maximise performance Meridian Audio Limited (DACs) to drive individual amplifiers which while minimising the size and weight of the www.meridian-audio.com power the loudspeaker drivers directly, installation. In this case, the DSP approach McLaren 12C 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 driving activity. The Automatic Volume Control function adjusts the volume of the sound system to compensate for estimated engine, road (tyre) The amplifier/DSP unit and wind noise. There are three settings for allows the maximum performance to be Amplifier unit AVC: Off, Min and Max. ‘Off’ disables the AVC developed from smaller, lighter loudspeaker Amplification and DSP capability are function and the volume remains constant at assemblies. DSP active crossover technology contained in a digital amplifier unit, which the user-selected level regardless of vehicle also dispenses with heavy, bulky conventional is supplied from the system’s head-end speed. ‘Min’ is the lowest setting of the AVC crossover components while at the same time source unit with either two or six channels system: the volume adapts gently to vehicle dramatically increasing audio performance, of digital audio at up to 96kHz sample rate, speed and other parameters. This mode has while permitting the use of smaller, more plus RS232 control data, via a single RJ45 been calibrated for smooth road surfaces. efficient and lighter amplification. The use connector. The amplifier unit has a DC ‘Max’ is the highest setting. Here, the volume of Class D amplification delivers maximum power connector and a 16-pin connector for adapts more aggressively to changes in power in a very compact and lightweight analogue audio output to the loudspeakers. vehicle speed and other parameters. This package, without the slightest compromise in It includes either four (2.2) or seven (5.2) mode has been calibrated for rougher road audio performance. channels of Class D amplification, depending surfaces. on the system, each channel delivering in The unique Meridian DSP-based approach excess of 40W into 4Ω. The AVC also raises the volume when the delivers a whole new level of performance engine is started, and compensates for a and excitement to high-quality stereo DSP Features and surround audio in the luxury high- The amplifier unit also contains the system’s performance sports vehicle market. DSP (Digital Signal Processing) capability in the form of a 200MHz dual core processor The Systems delivering 400 MIPS (million instructions per The two systems created for the 12C provide second). The DSP in the amplifier unit carries stereo and surround capability. In the case out a series of functions: of the stereo system, two door-mounted loudspeaker installations are employed, left • System Volume and right. In the case of the surround system, • Bass, Treble and Balance controls these are augmented with three additional • Rear Gain Control (Hi-Line system) full-range drivers. • Dynamic Range Control • Automatic Volume Control (AVC) The door-mounted assemblies (see below) • Automatic Tone Control (ATC) include both bass and full-range drivers, • Loudness filtering which are driven by independent amplifier • Channel format conversion channels. The bass drivers in the doors (including re-matrixing and stereo provide the bass for the entire system, width, and converting 2-channel input whether stereo or surround: thus the system to 5.2 and 5.1 input to 2.2) can be described as either 2.2 (stereo) or • Crossovers and bass management 5.2 (surround). Each driver is energised • Driver equalisation by its own super-efficient Class D power • Limiters and delay amplifier fed by individual location-specific equalisation and delay algorithms. The bass, treble, balance and rear gain controls provide the user with the ability to Main drivers in sealed enclosure McLaren 12C Meridian in-car audio lowered window by raising the volume on that More aggressive correction is applied when to ensure that bass signals from any channel side of the vehicle. The volume correction the powertrain mode is set to Sport or Track. are fed to the bass drivers on the correct side for the window function is road-speed of the vehicle, maintaining spatial accuracy dependent. Loudness Filtering allows the system to across the entire frequency range. compensate for human hearing’s reduced In Normal and Winter powertrain modes, sensitivity to low and high frequencies at In the case of a 2.2-channel in-car the AVC operates with road speed and lower sound pressure levels, boosting these installation, stereo source material is passed rpm. In Sport and Track powertrain modes, frequencies according to specially-developed through a user-variable stereo-widening the AVC also uses throttle position to add filter curve characteristics that are modelled system based on that used in the Meridian compensation for the increased engine noise on psychoacoustic research. The Loudness M80. Bass information from left and right is generated by the ISG. The correction curves Filtering technology builds on developments separated to drive the bass units while the for road speed and rpm are also slightly more first employed in Meridian’s F80, a luxury all- full-range drivers receive the mid and high aggressive to compensate for the additional in-one entertainment system, which is very frequencies, their locations optimised to noise and to add further aural excitement to highly regarded for its audio performance deliver precise imaging and sonic accuracy. these powertrain modes. and loudness compensation. Surround (5.1) source material is downmixed The Automatic Tone Control (selectable On/ The system head unit provided in the vehicle to drive the 2.2 output configuration, Off) boosts the bass when the engine is is able to deliver both stereo (2-channel) employing Meridian’s unique psychoacoustic started to compensate for the masking effect and multichannel surround (5.1-channel) technologies to deliver the best possible of the low frequency noise of the engine. signals. These signals are re-matrixed by spatial experience even though only two Both bass and treble are automatically comprehensive algorithms designed to output channels are involved. adjusted