USB Ground Isolator

[Smash54]

Hello All


I have a question maybe someone can help me out with about a Ground Loop hum I am experiencing. I have a Scarlett Solo Guitar Interface connected to my PC via USB cable outputted to a Tube amp. With the Amp grounded I get a 60 cycle hum if I lift the Ground on the Amp it goes away but don't want to leave it that way. I have tried those small dongle USB Ground loop isolators on Amazon but they won't allow the PC to power the Scarlett. What I was thinking was to do something with the ground wire on the USB Cable seen somewhere someone using 2 Diodes and a Resistor to isolate the ground looks like it would work any Ideas.

[0xdeadbeef]

You need one with a 5V/5V isolated DC/DC. Made some myself some time ago, but you can also buy something like that:
http://lemmini.de/USB%20Isolator/USB%20Isolator.html

[fourfathom]

Or look into a 1:1 audio coupling transformer between the amp and the interface.  This will break any ground loop.

[Smash54]

Thank you