I am new to gemini having a unit build cca 05/2018 with latest android and the sound is for sure stereo - tested with some stereo test videos on youtube. Not sure about the phase.
I know this is an old topic, but it seems to still be a valid concern, perhaps also for the Cosmo (still haven't got mine). My Gemini is an older x25 unit, but the speaker hardware should be identical. Below are two test tones I made. Beyond making the files about 35 times smaller, the heavy mp3-compression shouldn't affected them in any way that matters for these purposes. Btw. why does this forum still not support the FOSS formats Ogg Vorbis (from 2002) or Opus (from 2012)?
This is a 10-second
in phase ~523Hz (C5) stereo sine wave at ~-6dBFS.
In an audio editor, both the left and right channel should look the same (except minor mp3 damage).
Via correctly wired speakers, it appears to come from a point between my speakers.
Via correctly wired headphones, the sound appears to be inside the center of my head, much like a mono file.
This is a 10-second
out of phase ~523Hz (C5) stereo sine wave at ~-6dBFS.
[ Invalid Attachment ] In an audio editor, each channel should look like the other flipped upside down (plus minor mp3 damage).
Via correctly wired speakers, it sounds more like coming from each of my speakers.
Due to cancellation, it appears quieter than the in-phase file, when played at the same volume.
The volume may also appear to change more when moving my head, compared to the in-phase file.
Via correctly wired headphones, it sounds more as if I had one sound source on each side of my head.
(cancellation only happens via speakers, as the two sounds needs to physically interact in the air).
On my Gemini, when using the built-in speakers, my experience is other way around.
To me, on the built-in speakers, the apparent volume difference is very noticeable. I'd guess the short distance between them "helps" cancellation. But it's the in-phase file that sounds quieter, which suggests the speakers themselves are out of phase.