Coils of copper wires tend to pick up radio waves and other interference which will in turn be amplified through your loudspeaker. Radio interference can also be a sign of a bad ground signal, if your speakers have the option to be grounded and you have not yet done so we would recommend first doing this.

Your user manual will provide instruction on the best way to carry this out, however, as a general rule of thumb you will want to ground your speakers to your amplifier and any other equipment within your setup.

if you have an amplifier without a grounding pin and still wish to use this feature then you can run a length of cable from the earthing pin on the loudspeaker and connect it to one of the screws holding the amplifier chassis in place as this will have the same effect.