I have a Tone Board connected to my laptop via the provided USB cable and there seems to be an annoying hum. The pitch of the hum changes depending on what is being shown on my screen. Just flicking through different websites changes the pitch of the hum and it’s very annoying. Anyone else have this issue?
Hi Johnno:
May I know the model of your laptop you are using? not sure if it with low performance CPU 
Thanks!
Lenovo Yoga 720 it has i7 7700HQ
I think the power output of the USB port is not clean.
Hello, Have you tried a different USB cable?
I have tried 2 different USB cables for phones but they did not seem to work
Ok just tried with an ancient 2007 Dell Latitude laptop and it did not have any noise issues. Looks like my Lenovo laptop just has really shitty USB power
I suggest trying:
-plug the dac into a powered USB hub. This should clean up the power supply into the dac.
-update your laptop’s drivers ie graphics, USB, wireless, ethernet, etc.
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That’s a good idea. I was also thinking of cutting open the USB cable and hijacking the power lines and connecting them to a 5v 1a phone charger instead of going through the PC
Excellent idea. I think I have seen such cables for sale in the past.
Is the board in a case? Are you using WiFi?
Sometimes the interference generated by being too close to a WiFi adaptor appears to change with screen content (if the changes are Internet sourced).
Had a similar problem with a FiiO E10 some time back, despite case. Moving it further away from the WiFi adaptor solved it.
Otherwise, might be a ground loop?
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The board is not in a case but I cut up the Khadas USB C cable and connected the red and black power cables into another USB connected to a phone charger. That eliminates the noisy power. However, another high pitched noise was heard. I think my lenovo laptop’s USB output is just fucked. I tested this by unplugging the USB connected to the laptop and keeping the USB connecting the Tone Board to the charger plugged in meaning the board was receiving power but not data. This eliminated the noise. Sorry didn’t word that very well
please change tittle to : noisy lenovo power supply on usb
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Done
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Update: I was able to reduce the noise to the point where it didn’t bother me by changing my monitor refresh rate from 144hz to 60hz. Sad
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