Wire or cable conductor used to establish an electrical connection between a power amplifier and a loudspeaker also behaves as an antenna that can pick up radio frequencies (RF). Voice coils inside loudspeaker drivers are similar.
These high frequencies are fed to amplifier's input via feedback line, and cause distortions that can be heard and are often described as graininess or coarseness of sound. The common way to minimise this high frequency smear is to apply filters that reduce the amount of radio frequencies being passed into the amplifier. but, filters can only progressively reduce this RF interference, not eliminate it. A lot better way is to eliminate antenna effect by covering the cables and the voice coils with a ground shield.
Incorporating the ground shield end eliminating RF influence is more effective if power amplifiers are close to loudspeaker drivers, as in our active loudspeakers.
Foundation #10: Active Loudspeaker design must eliminate radio frequencies being fed to the amplifier's input, which is caused by antenna effect of the loudspeaker connecting cables and the driver voice coil; a ground shield applied to the driver voice coils and to the cables connecting drivers to power amplifiers is the most effective way of achieving that.