PR’s Data (2008):

Fs = 38.75 Hz
Qms = 8.3150
Qes = 0.3024
Qts = 0.2918
Vas = 48.41 Liters
Cms = 2.792E-4 M/N
Re = 3.67 Ohms
BL = 13.36 N/A*
Sd = 0.0351 Sq. Meters
Mms = 0.06041 Kg
Ref Efficiency = 0.896 %
Predicted Output = 91.72 dB/1W/1M
Predicted Sensitivity =  95.10 dB/2.83v/1M
Xmax = 3.51 mm

*Notes say the Direct BL crosscheck was close, but PR does not have
 the exact number…