Ground Loop / Hum

[skinnyj]

I'm having what I think are two separate issues...

I have a nasty hum coming though my monitors. At first I thought it was my AX8, but at my drummer's house it is dead quiet. I do notice that, if I turn my guitar away from my computer desk, the hum will fade a little. I've read there are all kinds of variables that can create hum, from outlets to computers to monitors (screen not speakers). Where is the best place to start to track this down?

The second problem is a high-pitched whine that is coming from my interface. I've read that the cause is usually because the USB cable is being used to pull power and creating some sort of loop in the PC power. It it time to find an interface with a power supply?

[surfnorthwest]

Its simply the circuit your plugged into, most likely not your gear.

Start by identifying the circuit your plugged in to. Then find out how many outlets are on that circuit and whats plugged in. If you were not getting that hum at your house but are there it is most likely something is plugged in the circuit your using that has issues.

[skinnyj]

I think I got it almost figured out...

1) The ground lift on my AX8 was engaged. I switched it off and 90% of the noise was gone.

2) I think the USB noise issue is just my desktop PC showing its age. I plugged into my new laptop and didn't notice the USB whine. The USB ports are probably picking up fan noise in my desktop.

I'm still getting some loose RF noise from somewhere. I still get a faint hum. If I turn my guitar 180 degrees from my desktop, it is almost completely gone.

[Alpeggio]

Yeah I have to turn away from the amp when using higher gain, it's a confined space.