An apparatus and method of operating a liquid drop emitter, such as an ink jet device, for emitting a series of liquid drops using reduced energy, is disclosed. The method is applicable to a drop emitter comprising a liquid-filled chamber having a nozzle and an actuator, such as a thermal actuator, for applying pressure to liquid at the nozzle. The actuator has a movable portion and exhibits damped resonant oscillation having a fundamental period, TR, and a damping time constant, TD. Apparatus adapted to cause rapid displacement of the movable portion of the actuator in response to electrical pulses causes drop ejection and damped resonant oscillation of the thermal actuator. The method of operating comprises applying electrical pulses having a nominal energy if the actuator is quiescent or applying reduced energy pulses to the actuator if it is usefully oscillating due to a previous drop emission. By advantageous use of resonant oscillations of the actuator, overall energy usage is reduced, and the productivity of the drop emitter is increased.