Libratone Track Air+ earphones
Wireless, Bluetooth earphones from late 2019 / early 2020, priced at around $200. It received positive reviews for both build quality and sound quality and they sound very good in my opinion. Actual build quality is debatable though - they tend to be a little bit fragile.
Common issue: broken stem. It looks like stem is glued or welded to the main part, but this is not a strong connection.
Often they can be glued back together with cyanoacrylate glue, but in this case flex PCB connecting these parts was torn, so they were not repairable,
at least not without a donor.
Apparently charger box is communicating with earphones using UART, probably in a unidirectional way (battery charging state + pairing request).
There is a magnet around the row of connectors.
There are two microphones inside stem, one of them seems to have analog output (only three lines).
Main part is glued, but after a bit of heating it was not difficult to open.
Main SoC: Qualcomm QCC5121.
LIR ZJ1254 55 mAh LiIon cell.
This was a big surprise for me. These earphones sound good and I've always associated it with large diameter transducers, but this capsule
has external diameter of 5.1 mm, similar to eartip head external diameter. On the other hand its depth is 4.0 mm. And another weirdness: it seems
to be acoustically connected partially to eartip head and to the hole next to it (visible on the picture with ear proximity window).
Semi-transparent window for ear proximity sensor.
Ear proximity sensor.
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