A V8, a manual transmission, and plenty of character: CarRangers’ BMW 550i Touring has many of the qualities that make it a true enthusiast’s car. However, the stock sound system leaves room for improvement. So, together with Alex and Tim, we’re giving the E61 an AXTON sound upgrade—with matching speakers, our DSP amplifier, and a custom sound tuning.
The idea behind the project is clear: listening to music in the 5 Series should finally be just as much fun as driving it. Together with CarRanger, we want to show what a well-designed upgrade with a reasonable price-to-performance ratio can achieve. To do this, we’re using the existing mounting locations and preserving the original interior look.
Alex and Tim are heading to Gebenstorf, Switzerland, for this. There, we’ll spend a day together installing and fine-tuning a sound system, and by the time they’re on their way home at the latest, they’ll be convinced of how effective it is.
The Starting Point: What Can the BMW Standard System Do?
Before we begin the upgrade, we’ll test the existing system. Using a measurement microphone and pink noise, we’ll measure the frequency response at the listening position. The result: The stock system is by no means a disaster. Aside from some bass boost, there are a few irregularities in the frequency response.
However, a frequency response alone doesn't tell the whole story. When it comes to listening to music, what matters most is how clearly subtle details come through, how precisely voices are positioned in the space, and how dynamic a system sounds. This is exactly where we want to focus with our upgrade.
While taking it apart, we also discovered something unusual: there are no tweeters behind the grilles in the rear sound stages. In this Touring model, the rear speakers are located in the headliner—not in the rear doors.
We install these AXTON components
| Component | Role in the Project |
| ATS-B102C | Component system for the front, including separate tweeters and crossovers |
| ATS-B102XS | Two coaxial speakers for the rear mounting locations in the headliner |
| ATS-BSUB4 | Under-seat subwoofer for the bass range |
| A894DSP | Eight-channel DSP amplifier, operated in 4.2 mode for this project |
| ATS-ISO 8119 | Matching plug-and-play wiring harness for connecting the amplifier in BTL 4.2 mode |
In addition, we use the extension cord required for this installation and a plug-and-play power cable.
Our vehicle-specific speaker connectors make replacement easier: We can connect the speakers without having to cut or solder the existing connectors. However, some installation work is still required—especially when accessing the under-seat subwoofers and routing the amplifier wiring through the vehicle.
More details up front, more reinforcement under the seats
With our ATS-B102C, we’re equipping the BMW not only with new midrange drivers but also, for the first time, with tweeters in the designated mirror triangles. This step lays an important foundation for greater brilliance, audible musical detail, and spatial depth.
For the bass foundation, we install the ATS-BSUB4 under the front seats. Their 20-cm cones offer more surface area than the 16-cm stock speakers shown in the video. Combined with the appropriate driver and the additional amplifier power, this creates the conditions for significantly more impact and dynamics in the bass range.
The Final Touch: Our Coordination with the DSP
New speakers and more power form the foundation. To ensure that this comes together as a cohesive system, we then fine-tune the A894DSP to match the acoustics of the BMW.
To achieve this, we measure each speaker individually and specifically correct any noticeable peaks in the frequency response. We deliberately avoid simply filling in acoustic cancellations with additional volume: Increasing the power does not automatically eliminate such cancellations and would only place an unnecessary strain on the speakers.
Next, we adjust the time alignment. This helps compensate for the varying distances between the speakers and the listening position and creates a clearer soundstage in front of the listener. We also integrate the rear speakers in such a way that they add more spatial depth to the soundstage without pulling the front soundstage apart.
As part of this project, we are making the preset created for the BMW available in the AXTON Cloud. If you have different speakers or specific sound preferences, a specialist dealer can help you with a custom setup.
CarRangers Listening Impression: “A completely different world than before”
After just a brief listen, Alex’s verdict is clear: “It’s a completely different world than before.” He’s particularly impressed by the punchy bass.
On the drive home, this impression is confirmed. Alex and Tim listen to music at length and emphasize, above all, the huge difference compared to the initial situation. For them, the clear sound reproduction, the spacious soundstage, and the powerful bass foundation represent the decisive improvement.
When comparing it to the BMW Logic 7 from back then, Alex sees the modified system as having an advantage, especially when it comes to bass. In our conversation, however, we also acknowledge that the spatial capabilities of a system with more speakers cannot be fully replicated. For CarRanger, what really matters is the result in everyday use: listening to music in this car is now a real pleasure.
How much does an upgrade like that cost?
Our goal for this project is to achieve a result that’s also affordable for an older classic car. The prices mentioned in the video for the front system, two rear speakers, an under-seat subwoofer, and a DSP amplifier total 985 euros. Including the necessary cables and other accessories, the total cost of materials comes to around 1,200 euros.
The total cost, including installation and calibration, depends on the vehicle and the scope of the work. In this E61, in particular, running the cables from the front to the rear-mounted amplifier increases the amount of work required.
A unique look, a new musical experience
Along with our sound upgrade, we’re installing a CarPlay retrofit solution sourced separately by CarRanger. It enhances the original display with modern smartphone features and is a standalone component of the project.
Together, we’re taking the BMW a big step forward in everyday life: The original interior look is preserved, while music and navigation can be used in a modern way.
For us, the CarRanger project shows just how much we can get out of a simple factory system with the right components and careful tuning. The result is a BMW 550i Touring that retains its character—and in which Alex now enjoys listening to music even more.
You can see the entire conversion—including measurements, installation, and CarRangers' impressions—in the video on YouTube.
