The below article will inform about the best practices for upgrading the audio on the
Mercedes Benz GL / GLS Class
(2012 – Present) Model X166

 GL / GLS Class X166 (2012-Present)


The Mercedes Benz GL / GLS Class is a good European full-size SUV for a premium audio upgrade. The car has a total of between 12 to 14 speaker slots (depending on variant) which are evenly distributed and staged for an excellent stereo as well as surround sound response. This is mainly in front to give the driver, co-passenger and middle row seat occupants a rich and clear music experience. The 14 speaker, Harman audio setup on the  GL / GLS Class reproduces a clear and natural sound output. The Harman factory amp is paired very well with the speakers in the car, positioned in appropriate slots and tuned to deliver crisp and clear audio response to the cabin occupants. Though this audio setup sounds quite balanced, it lacks head room. However, anyone seeking a higher end sound quality are the ones who consider upgrades over the Harman setup. The Harman audio setup is a good benchmark to match or to improve upon in case of an audio upgrade on an GL / GLS  .

The purpose built speakers in the Harman Audio variants do sound good to passive listeners. But, the end effect just does not work for some who are used to a higher level of sound quality at home, in their AV rooms or in another one of their premium cars with a higher end OE audio like Bang & Olufsen or Burmester and more.
Mercedes Benz have installed large 6.5” speakers in the front doors in a way that brings acceptable lows (bass) right up front in the GL / GLS . There is a Subwoofer / Bass speaker installed in the boot (Harman Audio Variant) add lower frequencies / Bass, also providing  a roomy feel in bass reproduced in cabin. The problem actually lies in the actual build of the speakers and OE amplifier, which are purpose built and are meant to sound average to the experienced listener or music lover or audiophile.

Standard Speaker slots / locations of equipment in Harman variants:

10 speakers in 4 doors, comprising of 4 tweeters / high-frequency drivers on the front and rear doors, 2 mid range speakers in the front doors  and 4 mid woofer / speakers on all four doors.  1 speaker in the dashboard (Center channel speaker), 2 surround speakers at the 3rd row of seats and 1 subwoofer / bass driver in the boot. These variants come with an amplifier which powers all the speakers in the car and is located below the front passenger seat.

Mercedes Benz GL


Due to the build and overall cabin volume, the  GL / GLS  needs powerful speakers in order to produce a clear and balanced music experience. The doors are built quite strong and sealed off with full acoustic foam damping or full cladding, which produces deeper bass response compared to other cars in the same category. On the Harman variants speakers are placed in locations to emulate a surround sound effect.

Mercedes Benz GLS


Almost all Mercedes Benz cars suffer plastic creaking and degradation on Indian roads due to the poor condition of the road surfaces, pockmarked with pot holes and ridges. Though this problem can be addressed with damping and soundproofing, some minor creaks here and there crop up in some Mercs’.


Full Upgrade on Harman Audio Variants:

The cleanest method of upgrading the audio on any premium car is to follow the least invasive wiring method. The right way of upgrading the audio on the non-Harman variants is to start with configuring a better source unit or entertainment system including basic features like USB, Bluetooth etc., an aftermarket sound processor / signal processor connected to the source unit acting as the master controller for the rest of the equipment to be added.  The next step is to select sets of speakers and matching amplifier(s) staying well within the provided space in the car, which in case of an  GL / GLS  is a medium amount of clearance (4 to 10mm). The final speaker configuration is a front 3Way setup (Mid-range speakers and Mid-bass speakers in doors, tweeters in the A pillars) and Rear 2Way (Tweeter and Mid-range speakers in doors) speaker setup.  An 8” Subwoofer replacement is to be placed in the stock location in the stock slot on the left side of the boot or a Subwoofer in an enclosure for a deeper and more powerful bass response. All of this has to be powered by amplifiers with matching power and sound signatures to achieve a unique auditory experience as per user needs.

“ Some Tech Gyaan-
A Digital Signal Processor sums up the signals from the Mercedes-Benz Main Entertainment Unit to flatten the input signal to provide a clean and controlled output signal to the aftermarket amplifier(s) to reproduce a very clear audio experience in cabin. “

Tuning and Room / Cabin analysis has to be performed extensively to recognize the points at which the Frequency responses have to match and merge. The installation is very similar to the Harman Audio variants, however certain source wiring configuration changes based on whether the Harman OE amp is retained or not (depending on configuration). Room / Cabin Analysis and Tuning of the audio takes some time and patience in order to achieve a perfect balanced sound. A stunning sound stage can be achieved with the right equipment and tuning setup.

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