ART CleanBOX II 2-channel Hum Eliminator The safest way to eliminate unwanted noise in your live sound setup is with the ART CleanBOX II Hum in an audio system is often caused by loop effects which act like antennas Typically, these loops are connected via grounds, more commonly called "ground loops " These loops can easily pick up a 60Hz (or higher harmonics) hum transmitted by electrical wiring Here are some common examples of ground loops where the CleanBox II can eliminate the hum: The power ground of a synthesizer, connected to the signal ground of the synth, into a mixer's ground, then into a mixer's power ground