The voice - coil is driven by a low - frequency audio signal from an amplifier ; common shakers typically handle 25 to 50 watts of amplifier power .
The shaker houses a small weight which is driven by a voice coil similar to those found in dynamic loudspeakers .
The voice coil     is driven by a low - frequency audio signal from an amplifier ; common shakers typically handle 25 to 50 watts of amplifier power .
The shaker houses a small weight which is driven by a voice coil similar to those found in dynamic loudspeakers .