Abstract: In an ink jet recorder, a ferrofluid ink is supplied under pressure to a nozzle to form a continuous ink jet stream. The jet stream is subjected to two or more perturbation forces out-of-phase with each other causing the satellites and drops to fast merge. Plural electromagnetic transducers are located at spaced locations along the stream and energized to produce out-of-phase perturbations on the stream. The spacing of the transducers is differentially related to spacing of varicosities or ink drops produced by first transducer. The out-of-phase perturbations can also be obtained using an electromechanical transducer and electromagnetic transducers located out-of-phase or energized out-of-phase with each other.