Isolated Ground causes ground hum.

What do you mean "isolated ground?"

I hammered three copper rods under the ground then linked them together with a solid 4 awg copper wire and through the exterior wall into my music room.

When i touched that wire to the ground post on the preamp, hum occurred. Thanks 

@dangcaonguyen

By law, you MUST bond them to the house ground.  You can't just create a new ground field, and run a copper wire to your outlets and call it ground.

Best,
E

@erik_squires 
Thank you,
and that was what I did. My outlet is still keeping as normal, 1 ot, 1 neutral, and 1 ground. I only added the extra isolated ground bond the the chassis of the preamp. Is it the same as I bond it to the common ground of the Edison?
Please let me know if what I an thinking is right?