When your band plays in different locations on a regular basis, noise in your P.A. system is a very common, and sometimes a very difficult problem to solve. Noise comes from many sources. Some of the most common ones are:
1. Poor cables on the inputs
2. Fluorescent lights
3. Dimmers
4. Poor design, particularly shielding and location of the mixer and power amps power transformers
5. Poor A/C wiring in the location where the P.A. is being used
6. Radio stations or othe…