Patent ID: 8300874

Claim:
A loudspeaker comprising: a speaker body; a speaker cone disposed at least partially within the speaker body, the speaker cone having a narrow end and a wide end; a cylindrical magnet disposed adjacent to the narrow end of the speaker cone, the cylindrical magnet moveable from a first position to a second position; a piston connected to the narrow end of the speaker cone, the piston comprising: a permanent magnet; and a wire wrapped around the piston; a first portion of the piston being disposed within the cylindrical magnet when the cylindrical magnet is in the first position, and a second portion of the piston being disposed within the cylindrical magnet when the cylindrical magnet is in the second position, the first portion being larger than the second portion; and an indicator moveably connected to the cylindrical magnet, the indicator comprising: an indicator strip; and a moveable arm in physical communication with the cylindrical magnet; an end of the moveable arm being disposed in a first region of the indicator strip when the cylindrical magnet is in the first position, and in a second region of the indicator strip when the cylindrical magnet is in the second position, the indicator strip identifying the position of the cylindrical magnet relative to the piston.