How Speakers Work

The key working components of a loudspeaker are shown in the diagram below. When an electrical current passes through a wire coil (the voice coil) in a magnetic field, it produces a force which varies with the current applied. The cone, connected to the voice coil, moves in and out, creating waves of high and low air pressure. The coil and magnet assembly are the 'motor structure' of the loudspeaker. The movement is controlled by the loudspeaker's suspension which comprises the cone surround and the 'spider'. The surround and spider allow the coil to move freely along the axis of the magnet's core (or 'pole') without touching the sides of the magnetic gap.