How do I install a subwoofer in my Mercedes Benz?

This blog will explain the procedure to install a subwoofer in a Mercedes Benz car and answer the following questions: why is a subwoofer necessary for a sound system? 

How do I install a subwoofer in my Mercedes Benz?

You can install a subwoofer in a Mercedes Benz in the following ways:

  • Select a subwoofer for a car.
  • Select a compatible amplifier.
  • Installation location for the subwoofer and amplifier.
  • Install the wiring harness.
  • Check the operation of the subwoofer.

Let’s take a closer look at each of the steps:

Select a subwoofer for a car

Mercedes Benz offers a small subwoofer in the standard sound system in all the models but the sound levels can be inadequate for some customers. A factory-fitted large subwoofer with extra speakers is only available on the top-end models with a hi-fi sound system.

There are plenty of subwoofers available in the aftermarket that can perform better than the stock subwoofer in the standard sound system. Subwoofer speakers with 8 to10 inch drivers are suitable for sedan and SUV models in Mercedes Benz.

It is also possible to install a 15-inch subwoofer if there is space and a compatible amplifier. There are subwoofers with inbuilt amplifiers, the installation of this type is easy but the overall size is big. So it is only possible to keep the box in the trunk.

The subwoofer should be at least 100 watts RMS, this will provide a decent output and a balance between the bass, mid-tones, and treble. It is recommended to get a higher wattage subwoofer and then control the gain as it allows room for any future upgrades to the sound system.

Select a compatible Amplifier

A subwoofer needs an amplifier to operate as the power from the factory-fitted amplifier is not sufficient. There are different types of amplifiers available in the aftermarket that can be installed in the Mercedes Benz.

Select an amplifier with a minimum power rating of 250 watts, the most popular type is the monoblock amplifier. It can power a single subwoofer, if you want to install more than one subwoofer then 2 channels or a multi-channel amplifier is recommended.

Sound amplifiers also have built-in audio processors so the overall output can be tuned after installing the subwoofer. There is also a gain controller for the output of the subwoofer, reducing the gain turns down the volume of the subwoofer speaker.

The cost of the amplifiers depends on the wattage and the number of channels it can support. Amplifiers can be big in size with a large heat sink to dissipate the heat and need an ignition ON signal to switch ON and OFF with the car.

Installation location for the subwoofer and the amplifier

The most common location to install a subwoofer in your Mercedes Benz is the trunk of the luggage compartment. A subwoofer is installed in a box to get maximum bass, the shape of the box depends on the space available.

There are a few compatible subwoofers drivers that can be installed on either side of the trunk. There is empty space behind the luggage compartment panel and as the rear compartment fuse box is located behind the panel, the electrical wiring can be made simpler.

The amplifier should be installed close to the subwoofer, there should be space surrounding the amplifier as it gets hot when the subwoofer is working. If two amplifiers are installed side by side, they should not be covered by any luggage compartment panel or insulation material.

Install the wiring harness

The installation of the electrical lines and the wire for the subwoofer is the most critical task. Mercedes Benz cars have the main battery located in the engine compartment or under the driver’s seat. The amplifier needs the power supply from the main battery.

A 4 gauge copper wire must be used for the power supply of the amplifier and a fuse can increase the safety of the amplifier. Aluminum wire is not recommended because it can heat and increase the line resistance.

The circuit 15 signal or the remote line can be connected to the cigarette lighter 15 A fuse. However, there are plenty of empty slots where a fuse and the remote line can be connected to get the circuit 15 signal. Use a digital multimeter to find the circuit 15 power supply in the fuse box.

If the amplifier does not have an inbuilt line output converter, locate the speaker wires and create a Y joint for the input signal to the amplifier. The Mercedes Benz head unit does not have a pre-amp output and there is no RCA connector on the factory amplifier.

The speaker wires are twisted to reduce the interference, check the vehicle wiring diagram for the positive and the negative electrical line. The subwoofer can be directly connected to the amplifier with the output electrical lines.

Operation check

After the installation is complete, install all the interior panels and check the operation of the subwoofer. The output can be tuned with the help of a digital sound processor and equalizer settings. 

If the subwoofer or amplifier is not working after installing the electrical wiring harness, check the ground point of the amplifier. There should not be more than 10 wires connected to a single ground point.

Use a paint scraper and remove the body paint on the threads of the ground point. It is not necessary to strip the paint at the bottom of the ground point as the ground signal is connected via the threads of the bolt.

Why is a subwoofer necessary for a sound system?

A subwoofer is a speaker that delivers low-frequency sounds. The standard frequency range is 20-200 Hz and the standard speakers cannot produce this low frequency. This frequency is responsible for the bass.

It can also reduce the load on the smaller speakers and prevent any damage to the diaphragm. The distortion of the sound is also reduced as a dedicated speaker is producing low frequency, the standard speakers can produce mid and high tones.

Additionally, the bass response of the subwoofer is better than the standard speakers, most of the speakers can only go as low as 50 Hz. The immersion of the surround sound system is more if there is a subwoofer that can produce a frequency of 20 Hz.

The only drawback of installing a subwoofer and an amplifier is the battery drain. The main battery is subjected to additional load and the battery management system in Mercedes Benz cannot control the amplifier as it is not connected to the CAN network.


This blog explained the procedure to install a subwoofer in a Mercedes Benz. Installing an after-market subwoofer can be a less expensive way to increase the quality of the sound system but it will void the manufacturer’s standard warranty.