Read-write head flying height controlled through micro-actuator assembly. Flying height controlled using DC line and ground line. Lateral position controlled using them and AC line. Micro-actuator assembly operates through three terminals coupled with these lines. Head gimbal assembly contains micro-actuator assembly mechanically coupling to slider with read-write head. Actuator arm includes at least one head gimbal assembly. Actuator arm assembly includes at least one actuator arm. Voice coil actuator includes actuator assembly. Hard disk drive containing voice coil actuator. Electrical interface circuit includes ground port, DC port, and AC port, for micro-actuator assembly. Servo controller drives micro-actuator assembly to control flying height and lateral position, preferably including electrical interface circuit. Manufacturing head gimbal assembly, actuator arm, actuator assembly, voice coil actuator, and hard disk drive, and products of these manufacturing processes.