I have the same noise which has gone after unpluging usb cables from OT and AnalogHeat. Problem is that I have no idea how to cover this ground pin of usb cable. There is written something about post explaining how to do it. I will be grateful if you give me a link to it or say something more about this covering? Thx a lot!
I did it 
there was enough to cover just one end of usb cable. Noise was made only by OT and there was no need of fixing AnalogHeat cable as well.
try plugging the sound from octa into your soundcard, use midi cables for data transfer and the plug your soundcard into your mackieā¦ see if it solves it. ā octa - soundcard - mackie. no usb leads, just midi cables.
Give this a watch, it helped me.
Anyone else getting a background high-pitched noise when OT connected via usb? I have the some problem sometimes with my Sub37 via usb. I have a MacBook Pro connected to the power outlet, and OT connected through Overhub together with the rest of my Elektron boxes, but only the OT gives off this noise. When I unplug he usb cable it goes away. Ideas?
Ps. I read somewhere that a user had solved the problem by putting a small a piece of tape on a connector somewhere but canāt remember the details.
This probably wonāt help you, but itās related ā¦ I keep my octatrack disconnected from my computer unless Iām doing transfers. Thatās because on a relatively recent version of software, leaving it connected would freeze the OT (MKII). So now I am superstitious about it.
I donāt know why or if it is fixed now, and I donāt know if thatās useful to know or not
Maybe the problem + possible solution was already discussed here?
you can get usb ground loop lift thingsā¦ (not that cheaply sadly) - had to do the same for my Miniaturā¦
Definitely a problem for analog stuff apparently, but I guess maybe for anything that is plugged into USB and the same mixing desk/audio device as the thing providing the USB?
You can also just cut a thin piece of electrical tape and place it over the power pin (pin 4) of the usb lead as well and this works pretty goodā¦ or cut the appropriate lead within a cable.
I ended up buying the isolator/lift thing thoughā¦
oh, what PomPomOne said.
Interesting, Iām now reading lots of articles on hi-fi and DIY forums where they have similar, but not EXACTLY the same problems. They all seem to have this ground pin on the USB in common. I have no noise coming from mouse movement, but a static high pitched noise like some of them describe. I willl def try put electrical tape on the ground pin when I get home. It just seem strange to me that the AH, A4, AH and DN have no issues?
Edit: I do think Iām running unbalanced cables from my OT mkI to my fire face UCX. Maybe Iāll try switching to balanced just to before I go ahead with the ground pin?