A jet break-off length control apparatus for a continuous liquid drop emission system is provided. The jet break-off length control apparatus comprises a liquid drop emitter containing a positively pressurized liquid in flow communication with at least one nozzle for emitting a continuous stream of liquid. Resistive heater apparatus is adapted to transfer pulses of thermal energy to the liquid in flow communication with the at least one nozzle sufficient to cause the break-off of the at least one continuous stream of liquid into a stream of drops of predetermined volumes. A sensing apparatus adapted to detect the stream of drops of predetermined volumes is provided. The jet break-off length control apparatus further comprises a control apparatus adapted to calculate a characteristic of the stream of drops of predetermined volumes and adapted to provide a break-off length calibration signal to the resistive heater apparatus wherein the break-off length calibration signal is determined at least by the characteristic of the stream of drops of predetermined volumes. Further apparatus is adapted to inductively charge at least one drop and to cause electric field deflection of charged drops. The present inventions are additionally configured to control break-off lengths for a plurality of streams of drops of predetermined volumes by determining a break-off length calibration signal that contains information specific to the plurality of streams of drops of predetermined volumes. Jet stimulation apparatus comprised of a plurality of thermomechanical or electromechanical transducer devices that transfer mechanical energy to the fluid are claimed. Methods of controlling the jet break-off length are also disclosed.