Eliminate or isolate excessive sources of electromagnetic, or EM, radiation. Common culprits are fluorescent lighting fixtures, CRT monitors and TV sets, or any device containing a transformer. Replace fluorescent lights with other types, and replace CRTs with flatscreen LCD or plasma monitors. Relocate equipment with transformers, if possible.
Address items that are susceptible to picking up induced hum. Single-coil guitars are a major source of background hum. Position the guitarist away from amplifiers or other EM sources, and have him adjust his position until the hum is at its lowest point. When power and audio cables are close together, adjust routing so they cross each other at right angles. This minimizes the cross-section of audio cable exposed to induction.
Treat unpreventable hum with signal processing. Noise gates are often used with guitars to block hum when no performance occurs. Use aggressive parametric equalization to remove 60 hertz content from any audio. Only a few bass instruments create notes this low, so notching this frequency has little effect on most audio signals, save for noise reduction.