Ground Loop Help

[lionel reed]

Hi
I am tearing my hair out in the studio trying to record some Audio.
I have a Mac Pro/Apogee ensemble with various hardware synths.
I am trying to record My 808. The apogee records on the quiet side.
When I boost the signal I can hear background hum in the audio.
I purchased a Berhinger Ultra DI Pro (I Know), When I use the ground lift it seems to make the hum worse.
I admit my studio isn't the tidiest but I have listened through the Apogee with the volume right up full and unplugged each piece of equipment in order to isolate where it is coming from but cannot locate it.
I am running out of Ideas. I got rid o my desk as I was getting too many audio problems through that.
Any thoughts?

[chris319]

Bad power supply?

[Black Shadow]

Try using separate power outlets: one for your audio equipment and one for your computer stuff.

Not just different sockets, but use one in the room itself and the other one coming from a different floor with an extension. Might do the trick.

[GotGear?]

Are there any flourescent lighting fixtures in the room or a light dimmer?

[lionel reed]

There Is no Dimmer in the room.
Don't how my girlfriend is gonna feel about extension running up the stairs but ill give it a try

[drBill]

Do a search for "star ground". Or buy an expensive balanced power unit. As someone else mentioned, it COULD be a bad PS, but most likely you do not have an appropriate "grounding scheme" for your studio. Generally, only ONE path to ground, all AC outlet grounds must not daisy chain and must all go to the same place. ANY gear - computers, console, outboard, amps, etc. go to the same ground and only have one path there. Simple, and possibly the most complex thing you will ever attempt.