daddyopapa

It's not just a ground loop hum, it's the actual signals coming off the computer. Beeps, blips, morse code sounds, oscillations.

Trouble shooters listen up. I normally run my HD500 into a powered monitor via XLR cable. My home set up is in front of my laptop I use for recording. Always quiet with no interefernce. I also have tube amps that I play when the laptop is on. No interference. The other day I wanted to experiment with running the HD into a tube amp via 1/4" instrument cable. Got this weird interference like a UFO command centre. Didn't matter if the guitar was even plugged in so it's not the pickups. Turned off the computer and the sound went away. OK - it's the computer. Then I turned the computer back on - sound came back. Then I unpluuged the USB cable from the computer to the HD - sound went away. So the only time the interference happens is when I run 1'4 cable to a tube amp and have the computer on and the USB connected. Why?