The below article will inform about the best practices for upgrading the audio on the
Mercedes Benz C Class
(2007 – 2014) Model W204

C Class W204 (2007-2014)

 Synopsis:

The Mercedes Benz C Class is a good compact sedan for a premium audio upgrade. The car has a total of between 6 to 10 speaker slots (depending on variant) which are evenly distributed and staged for an excellent stereo response. This is mainly in front to give the driver and co-passenger a rich and clear music experience. The 10 speaker, Harman OE audio setup on the top end C 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 at higher volumes. 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 beat in case of an audio upgrade on a C Class.

The basic built speakers in the non-Harman Audio or commonly called Non-Option Sound variants do sound good to passive listeners. But, the sound response just does not work for anyone who is used to 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.
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 C Class. There is a Subwoofer / Bass speaker installed below the rear parcel tray to add lower frequencies, creating 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 Non-Harman variants:

6 speakers in four doors, 4 mid woofers / speakers and 2 tweeters. This setup comes with a Basic entertainment unit up front with a CD Changer. This setup in the car today is quite outdated and aged.

Standard Speaker slots / locations of equipment in Harman variants:

6 speakers in 4 doors, 1 speaker in the dashboard (Center channel speaker), 2 tweeters / high-frequency drivers on the front doors, 2 surround speakers and 1 subwoofer / bass driver on the real parcel shelf. These variants come with an amplifier which powers all the speakers in the car and is located on the left side in the car’s boot below the stock parcel tray and above the left wheel arch.

Pros:

Due to the compact build and overall cabin volume, the C Class does not need very 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, 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.

Cons:

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’. The rear parcel shelf inside which the factory fitted subwoofer is mounted jarr at higher volumes, though it can be rectified with some damping and sound proofing.

Solutions:

Full Upgrade on Non-Harman 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 installing an aftermarket sound processor / signal processor connected to the Mercedes entertainment  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 a C Class is a medium amount of clearance (4 to 10mm). The final speaker configuration is a front 2Way or 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 rear parcel tray 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 as per individual listening preferences.

“ 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. “

Full Upgrade on Harman Audio Variants:

Now, this variant of the C Class already has a decent sounding setup but lacks depth and headroom. What is needed is a compatible pre-amp unit which will allow the existing Harman amp to operate seamlessly with the aftermarket equipment we plan to add. 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 Non-Harman variants, however certain source wiring configuration changes based on whether the Harman OE amp is retained or not. 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 setup.

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