A prototype of monolithic piezoelectric line ink jet printhead, which has 108 mm print width, was proposed at NIP21 by one of the authors. It enables variable volume drop ejection at 20 kHz frequency from 2,656 nozzles arranged in 108mm x 16.8mm area. And it achieved 600 dpi x 600 dpi single pass printing at 847 mm/s. Then, its' highest drive frequency was raised up to 24 kHz for faster printing (reported at NIP 23).Again, it is raised further up to 30 kHz by modifying ink viscosity as well as channel design. The latest model enables 600 dpi single pass printing at 1,269 mm/s with variable drop volumes between 5 and 12 pl. The drop velocity trend against firing frequency becomes more consistent up to 30 kHz. Also, drop deviation is improved for better image quality by modification with nozzle plane.