The HD measurements at distance 315 mm and voltage levels 2.83 - 11.2 Volt were carried out with High Pass Filter "on" (2nd order Butterworth type, 80 Hz cutoff, HPF2-80)
The HD measurements at distance 315 mm and voltage level 16 Volt were carried out with High Pass Filter "on" (2nd order Butterworth type, 150 Hz cutoff, HPF2-150)
The HD measurements at distance 20 mm and voltage 5.6 Volt were carried out with High Pass Filter "on" (2nd order Butterworth type, 30 Hz cutoff, HPF2-30)
Before taking the measurements the speaker had been very good boken-in