Mp3 player via line input to car radio connect

My cell phone has a built-in MP3 player. The music of this MP3-player should be played over the, in my car built-in, car radio be played back. Basically there are several possibilities for the connection. If the car radio had a line input then the connection can be made via an adapter cable to the line input of the car radio. For car radios with cassette function, the connection can be made via an adapter cassette. the adapter cassette has a cable with an appropriate connector and the audio signals are transmitted to the car radio via the audio head. If the car radio has neither a line input nor a cassette function, but z.B. If the radio is equipped with a CD player, the connection can be made via the antenna input using an FM transmitter. An FM transmitter is basically an FM transmitter that transmits with a low transmitting power and can be received by the car radio.

the car radio installed in my car has among other things the following data: amplifier with an output power of 4 x 25 watt sinus, a tuner for FM, MW and LW, a MP3 capable CD player and a line input. Since the built-in car radio has a line input, the connection should be made via this input. The line input of my car radio can be used to connect a CD changer or any other audio source with a line output. For the connection a suitable adapter cable was purchased. In addition, an audio adapter was required for my phone. The adapter cable was connected to the car radio and mounted in the car in such a way that the jack plug was always within reach and the cell phone could be connected if necessary.

Removing the car radio

To do this, first disconnect the battery’s negative terminal. Then the car radio was removed, according to the instructions in the installation manual, using special brackets.

Connect the adapter cable and test it

One side of the adapter cable was connected to the car radio. The other side was connected to the audio adapter of the cell phone. The audio adapter was connected to the phone. On the car radio it had to be configured that the line input should also be used. To do this, the AUX input was switched on in the menu of the car radio. After the AUX input was switched on, it could be selected via the source selection button. Using the source selection button could then be switched between AUX input, CD and radio. The system was put into operation and the MP3 playback on the phone switched on. Unfortunately, it was found that the MP3 playback did not work properly. There was a lot of noise and an unpleasant hissing sound.

Test with my old car radio

Since I still have my previous car radio and it also has a line input, I have installed this car radio once. However, it has no built-in CD player, but a cassette drive. The connection was made very similar to what was just described above. The car radio was from the same manufacturer as my current car radio. All electrical connections could be made directly by reconnecting the plugs. in the menu, the AUX input was also switched on and could then be selected via the source selection button. After switching on the MP3 playback on the cell phone, the playback was flawless this time.


I have the "old car radio" used for the test dismantled again and restored to its original condition. I first assume that the line input of my current car radio is defective. But it is also possible that the input levels of the line inputs of both radios are different, and the phone plays with one and not with the other. Since I want to continue using the current car radio, not least because of the MP3-capable CD player, I will not connect my cell phone to the car radio for the time being.

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