I have significant coil whine with my UDOO Bolt V8. This occurs when it is being "switched off" and the whine modulates with the inbuilt orange LED pulsing (pitching higher when on and lower when the LED is off). The whining originates from the Bolt itself, not the power supply. Do you other Bolt V8 owners also suffer from this?
UDOO Bolt (or any other SBC), when there is power present (even the PC is off), there will be a small amount current drain to get it into "ready to power on" state. In the case of BOLT, there must be a small DC-DC (say 12V to 3.3V) buck converter in operation. This type of switching regulators typically runs in the frequency range of 15 KHz all the way up to 100 KHz. I am not sure exactly the type used in BOLT, but I suspect the OP's hearing is extra sharp to be able to sensitive to the ultrasound range. View this as a blessing. I wish I can trade my long gone hearing with a dozen of BOLT , if there is such an "EASY" button to press.
I can confirm that this is also something I have noticed. Not sure how much of a nuisance it is for me yet but it is definitely audible.
Well, either I'm going deaf or my V8 doesn't have this issue, hopefully the latter as that would mean not all Bolts has the issue.
My phone can hear a peak at 16860.5Hz when it is near the Bolt. It is a long time since I could hear frequencies that high.
What software do you use for that ? I just tried using Spectroid (best rated free Android spectrum analyzer I could find) and saw no change i measuring next to the Bolt and 1 meter away.
What I said was that I saw no difference between measuring right next (less than 5 cm away) to the yellow flashing Bolt and measuring 1 meter away. Had there been any significant noise from the Bolt the two measurements should have had significantly different results.
Not sure where I read it but someone mentioned that the coil whine disappears if both the front USB ports are connected. I just gave it a try and it is does seem to fix the coil whine or at least reduces it significantly.
Yellow LED (power down state, USB-C powered) at 5 cm distance, my BOLT v1605B measured -86dB at 14.8KHz. (I can't hear it.)
Yeah, mine is pretty noticeable, enough to drive me crazy while turned off, I have tinnitus and this noise I could hear it from one room to another, what I do is fully disconnect while Bolt is not in use.
If you plug enough things in then the whining stops. Once I plugged in an HDMI cable and a c-type to two monitors the whining stopped.
Still an issue it seems on current units. Power over usb-c and ethernet connected, very noticeable coil whine.
I agree it is annoying, have to either unplug the power or keep it running if I am to sleep in the same room as the Bolt.
HDMI, USB keyboard and mouse, I have an external USB hub as well, as I read above the more you connected to it the better, though I just noticed the whining is gone even without those things on it anymore.