drivers are selected specifically for the system goals and compatibility with all other parts
from 3.3 manual
"Lower Midrange: 6.5" polymer cone in 10-liter anti-modal enclosure Long-throw 2-layer voice coil 42hfz free-air resonance Fc = 67Hz, OK; = 0.66 12dB/octave high-pass at 100Hz; 12dB/octave low-pass at 320Hz"