FairPhone USB-C to Audio jack adapter works only with some earphones

Hello everyone,
I just got a FairPhone 4 after a long struggle whether or not to buy it since I’m not a fan of bluetooth headphones, especially when outside.
I therefore also got the official FairPhone USB-C to audio jack adapter.
The adapter works flawlessly with my over-ear-headphones and my stereo. However, they do not work with the smaller earphones I use while running or cycling. I tried two different models, neither of them work. Instead, a notification is shown that the connected device is charged via USB (which doesn’t make sense, since the earphones have no battery).
Interestingly, if I connect my over-ear-phones, play music and then quickly (within about a second) change to the earphones, they work for about a minute before the music stops again. So it must be working somehow. Changing the cable every minute however is not a practical solution.
The earphones themselves work, also at my friend’s iPhone using a Lightning to Audio Jack adapter.

I tried to toggle the developer setting “Disable USB audio-routing”, also without success.

Does anyone have any advice for me except buying new earphones (which will then again be a gamble whether it works or not).
Thanks in advance!


Have you tried using adapter dongles from other phones or the generic ones sold br Apple and Samsung?

Cuz then you’ll know whether the issue lies with the dongle or the phone (or the small, but potential possibility that some headphones are just source sensitive and don’t like being plugged into the Fairphone 4).

No, I didn’t have access to another USB-C to audio jack adapter. I resorted to just buying USB-C headphones from Samsung, they were only a bit more expensive then getting another adapter where I’m not sure whether they will work. The USB-C headphones work without any problems.

In the future when I have some time I will upgrade to Lineage OS since I’m also not exactly thrilled about the Stock Fairphone ROM. I will give updates here when I did that upgrade since it may be a software problem.


My 2 cents
Have you checked that the smartphone is not connected at the same time to another Bluetooth device.

Hi, two things how I use headphones with my FP4:

  1. I use an “USB-C male to 3.5 mm female cable” from UGREEN to connect my headphones to the Fairphone 4. Never got any trouble with this adapter.
  2. I use the app “Poweramp” to play audio files.

Maybe this is something for you to try?

Best regards


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