My Samson Q2U used to record cleanly on my Windows 10 desktop, but it recently developed a constant low hum or static in the background. The same microphone and USB cable work perfectly on another laptop, even when tested right beside the desktop. I've tried multiple USB 2.0 and 3.0 ports, several recording programs, disconnecting other USB devices, plugging the PC directly into the wall, switching to 48 kHz, reinstalling the microphone, and disabling USB power-saving features. None of that helped. I also recently cleaned the PC with a powerful electric air duster, including around the power supply, so I'm wondering whether that could be related. Could this be grounding or USB power noise from the motherboard or PSU, and would a USB isolator be a sensible fix?
3 Answers
A USB isolator may help if the hum is being carried through the USB ground, but compatibility matters. The Q2U uses USB Audio Class 1, and some isolators don’t support USB audio properly or can’t provide enough power. Check that the isolator explicitly supports USB audio and the microphone’s speed and power requirements. Borrowing one or buying from somewhere with easy returns would be safer than assuming it will solve the problem.
This sounds more like a grounding or electrical-noise problem than an issue with the recording software. As a quick test, disconnect the monitor, speakers, and other peripherals one at a time and listen for changes. Also try a different wall outlet or power strip, and temporarily disconnect any analog audio cables. The PC being on a wooden desk doesn’t affect grounding; the important part is the mains earth and the connections between the computer and other equipment. Don’t defeat the ground pin or open the PSU. If the noise changes when you touch the microphone or PC case, that’s another clue pointing toward grounding or shielding.
I was mainly wondering what I could safely test myself. I’ll try another outlet and disconnect the monitor and other audio connections without modifying the PC’s grounding.
The recent cleaning could be relevant if the air duster was powerful enough to spin fans excessively, push dust into a connector, or create static, although it doesn’t prove the PSU was damaged. Shut the PC down, unplug it, and inspect the USB ports and internal connections for debris or anything loose; avoid opening the power supply itself. Software and sample-rate changes are unlikely to remove a constant hum when the same mic works cleanly on another computer. If possible, test with a powered USB hub or a PCIe USB card. If the noise follows the desktop but not the mic, the motherboard or PSU is the likely area to investigate.
An isolator is a reasonable editing-focused workaround, but I’d first test the microphone on the desktop with every other cable removed. If the hum remains with only power, USB, and headphones disconnected, the PSU, motherboard USB power, or a damaged port becomes more likely.