The HD measurements at distance 315 mm and voltage levels 2.83 - 11.2 Volt were carried out with digital High Pass Filter (2nd order Butterworth type, 1500 Hz cutoff, HPF2-1500)
"+FP" in the button names means that the measurements were carried out with the additional faceplate
"no FP" in the button names means that the measurements were carried out without the additional faceplate
The detailed review of the AT60NC-4 speaker