I have brought a Jl audio 12" W6v2 Sub:
Free Air Resonance (Fs): 25.0 Hz
Electrical “Q” (Qes): 0.480
Mechanical “Q” (Qms): 7.100
Total Speaker “Q” (Qts): 0.450
Equivalent Compliance (Vas): 2.82 cu. ft. / 79.9 liters
One-Way, Linear Excursion (Xmax)*: 0.65 in. / 16.5 mm
Reference...