“Most computer microphones use the third segment to carry bias power for the microphone.” https://en.wikipedia.org/wiki/Microphone_connector
I had thought it was to deliver sound to both sides (rather than left- or right-only) but here we are.
I have some headphones with a mic, but there is no bias voltage contact, only Left, Right, Mic(return?)and Ground. How does that work?
As well as everyone else’s answer here about bias power: it could also just be because a 3-pin TRS are cheaper/easier to buy and get assembly tooling for than 2-pin TRS. Economies of scale.
(For a good example of this: 3-axis accelerometers are cheaper than 1-axis and 2-axis ones. Everyone wants 3-axis for mobile phones, drones, human inputs and the like. You’re better off buying a 3-axis chip and ignoring the extra channels)
I don’t think we can tell from just a picture of the plugs. These are definitely two 3.5mm stereo jacks, colored headphone and mic. Maybe have a look at the manual? Or type the model number into Google? Or use a multimeter and measure the resistance.
What do you mean by stereo wire? It’s got 3 contacts on the 3.5mm jack, that’s enough to transfer analog stereo (GND, L, R).
So you have two low-quality mics that can distort your discord call twice as effective.
Innovation!
