PR’s Data (2009):

Fs = 27.31 Hz
Qms = 3.7880
Qes = 0.6929
Qts = 0.5856
Vas = 142.88 Liters
Cms = 4.073E-4 M/N
Re = 2.56 Ohms
BL = 7.27 N/A*
Sd = 0.0500 Sq. Meters
Mms = 0.08338 Kg
Ref Efficiency = 0.404 %
Predicted Output = 88.26 dB/1W/1M
Predicted Sensitivity =  93.21 dB/2.83v/1M
Xmax = 3.55 mm

*Notes say the BL crosscheck was close – will find
  and add, later.