Current circumstances (with COVID) caused a delay at the carrier but nothing the seller can do about that. Seller was great at following up on enquiries and communication generally was perfect. After reminding myself about adjusting the sensitivity with the resistor on the board had Pi driven music/light show in no time at all. Looking forward to playing with the light settings a bit more now
Sept. 3, 2020
Works well. "Full brightness" version is blindingly bright.
Today I received the ring (full brightness version) and soldered a 18650 Li-ion to it, although a smaller battery may do. It is blindingly bright, sufficient for being well seen in daylight shadow. The full brightness version may be a bit too much for a dim disco environment (unless you adjust brightness in the source code, recompile and download). A button is helping to switching between various preprogrammed light patterns and colors.
There is a tiny potmeter to adjust microphone sensivity. Medium sound level is required, even in the most sensitive setting. The micro is not very sensitive to rubbing the PCB on clothing, so you may wear the ring as a necklace.
Neither button nor potmeter are mentioned in the documentation.
Adjustable brightness, e.g. by long-pressing the button, may be a useful feature.
Response from MAT | Sept. 6, 2020
Thanks for your comment, Adrian.
You are right, the full brightness version may be too bright in some environments, and it would be useful to be able to modify it without having to recompile the source. I will add this feature soon in a new firmware version along wit more detailed documentation.