The HD measurements at voltage levels 2 - 5.6 V were carried out with High Pass Filter "on" (2nd order Butterworth type, 800 Hz cutoff, HPF2-800)
The voice coil current HD measurements at voltage levels 1.41 - 5.6 Volt were carried out with High Pass Filter "on" (2nd order Butterworth type, 800 Hz cutoff, HPF2-800)