Mercedes GLE 53 (2021) – Focal Inside

It was a cold January day when the Mercedes GLE 53 entered our premises. We immediately noticed that this was a brand new 2021 car that had *just* left the dealership! The car was equipped with the company’s “high end” offering, the Burmester system. Naturally we had, to have a listen to that. Surprisingly, we got very disappointed and so was the owner of the car.

I cannot believe that this is meant to be the upgrade version of the standard Mercedes offering. It sounds horrible and it does not do this lovely car any favors! Please tell me we can do something about it!

And that, became our mission for the next few months!


The Homework – The Design – The Timeframe

There was only one way to be sure what kind of speaker sizes we were going to be needing – taking the door panels off and the “flooring” to reveal the subwoofers. Once we did, we realized that Mercedes followed their usual path, using small 10cm speakers with separate tweeters, yes even for the center speaker but with a coaxial design, adding 2 x 20cm subwoofers to take care of the low frequencies.


Focal had us covered!

At the time, there was no plug & play solution available so we told the customer that we needed to do a little bit more research before we decide how to proceed. Luckily, Focal was just about to release a Mercedes Specific Line under their brilliant Focal Inside program. (Find out more here: – So we communicated this to the Mercedes owner and we all agreed to wait until these babies were available!

The Procedure

Once the products arrived we brought the car immediately in and started working on it, taking extra notes for everything we removed and comparing with the clearly superior Focal replacements. It was really hard for us to believe what we were seeing. The OEM speakers that were supposedly an upgrade from the standard system seemed so generic (The simplest paper-cone design!) that no one would ever consider them as an option even for free!

Here below we can see the component set that will be used for the front & rear doors. On the left side, the Focal replacements, on the right, the OEM speakers. The speakers use the legendary Flax Cone that discern from the Aria Series and Kanta Series of Focal’s super successful Home Audio lines.

Made in France but affordable, Flax cones are oriented towards acoustic performance, high-tech and give an original design to the brand’s speaker drivers!

After more than five years of research and development, engineers at Focal reveal in 2013 a new cone made of high-quality flax fibers. F cone are characterised by their natural sound, with low coloration, their richness of reproduction in the midrange register and their tighter bass.



F cones are made of high-quality flax fibers core enclosed by two thin layers of glass fiber. They satisfy the key criteria of a high performance diaphragm : high internal damping, high velocity of sound and high flexural rigidity.


All these criteria cannot be met by a mono-material cone. Sandwich technology greatly influences the neutrality of the sound produced by the cone, something, which has always been Focal’s hallmark. The expertise gained from the sandwich technology of the Utopia and K2 Power ranges enabled Focal to develop a revolutionary flax-fiber cone conciliating the 3 criteria.


Flax is twice as light as fiberglass, because the fiber is hollow. It also has very low elasticity which makes it ideal to increase the flexural rigidity of a sandwich structure. Moreover, it can be obtained in non-woven bundles of considerable diameter and it can therefore produce the thickness required for a sandwich.

Internal damping

Composite materials have properties suitable for applications where both rigidity and low mass are required. However, their disadvantage is that they lack damping, which leads to very poor control of vibrations. Recent developments in this field combining composites and natural fibers have brought unexpected opportunities. Flax fiber has an excellent internal damping of the same order of magnitude as the glass or Kevlar® fibers or aluminum.



Flax cones are designed and manufactured in France, from french flax fiber. France is the main cultivator in Europe of fiber flax, principally in Flanders, Picardy, Normandy and the Pas-de-Calais region. French flax is considered the best in the world.

Synthetic fibers or foams originating from petrochemical resources are subject to inflation linked to the sharp rise in crude oil prices. Organic or ecological textiles, like flax, are thus becoming more and more price competitive.

Because the “W” or “K2” sandwich have to be manufactured by hand, their range of application remains limited for reasons of cost. The industrial process developed to manufacture the “F” cones bring it within reach of very price competitive product ranges

Moving on, we can see the design difference between the Focal Subwoofers (Left) & the OEM ones (Right). The Focal Subwoofers use the already proven Polyglass cone Vs the generic paper cone of the OEM speakers. Polyglass is a Focal tradition that combines the excellent damping properties of paper with the rigidity of glass, translated into the listening experience through particularly well-defined midranges. The sound is warm, with no coloration.

The center speaker, installed, without any modifications at all! The fixing position was exactly the same and the plug connectors fit perfectly. This part of the installation was a breeze!

The big guns! The subwoofers are now installed at the OEM positions and are ready to be the heart of this system and ultimately the life of the party!

The results

Once we were done we spent a few hours just listening to the Focal work their magic. Everything was improved. EVERYTHING! The midrange was no longer “muffled”, the highs were no longer drilling your ears and the subwoofers punched out incredible amounts of bass with the precision that made Focal world-wide known! We were stunned. We could not wait for the customer to come and give us his feedback. We kept the car one more day for some final touches and we tried to play the system as much as possible so that the customer would need less time to burn in the speakers.

We were impressed with the efficiency of these speakers. Even though we did not change OEM amplifier, the speakers seemed to be driven quite effortlessly and he difference in sound quality was colossal.

Owner’s reaction

As soon as we sat in the car, the owner only said two words: “Amaze me!” – We chose our go to playlist on Tidal and as soon as Diana Krall sang the first verse of “Temptation” we could already see the emotions that a system like this can deliver, mirrored in his eyes. He was almost in tears! “At last!” he screamed. “Now I can hear some music!”. We nodded in agreement.

Honestly, you were recommended by many as the “go to place” for such a project and rightly so. I was so disappointed and angry that I had just purchased this beautiful car, only to have my experience sabotaged by a sub-par audio system that portrayed itself as “premium”. You cannot imagine the relief I am feeling right now. Thank you guys. – Owner of the GLE.

How did we do it

Here is a list of the products we used to make this happen!

Front & Rear Door Speakers – IS MBZ 100

Center Speaker – ICC MBZ 100

Surround Speakers – ICR MBZ 100

Subwoofers – ISUB MBZ 2