Inkjet developments move towards higher productivity and quality, requiring adjustable small droplet sizes fired at high repetition rates. Normally, maximum jetting efficiency is achieved by tuning the slopes of the driving waveform to the travel times of acoustic waves inside the channel. Important parameters are channel length, compliance of channel cross-section (through its impact on the effective speed of sound in the ink) and the inlet geometry (through its impact on the phase shift of reflected acoustic waves). In addition, nozzle size and drop speed are the main factors determining the default drop size. The shape of the nozzle is important for the acoustic impedance and thus for efficiency and damping (enabling high drop-on-demand frequencies).