I'm new to recording (just got Sonar), but not buzz. Broadly speaking, you probably have one of two problems:
- Single-coil pickup buzz
- Ground-loop
If your location seems to affect the amount of buzz (relative to location of amp/computer), that's single-coils.
More likely, you've got a ground-loop/problem. Common causes:
- Stomp-boxes plugged into A/C outlets - try batteries
- Other A/C units in your device-chain (like a mixer) - try plugging-in to a common outlet, eliminating anything you don't need (like a mixer), just for process-of-elimination
- Use of a laptop (horrible for buzzing/ground problems!) - Issolation transformer?
- Bad connection (bad ground) - use good contact cleaner like Caig "DeOxit"
I sometimes use an Ebtech "Hum Eliminator" (an issolation transforer).