NdRL 41 MkII Technical Data
 Frequency response (-3dB, ripples less than 2dB)
 2.8 - 40kHz
 Sensitivity (1W (2.0V), 1 meter)
 89 db (+/- 1dB)
 THD (DIN 45500)
 </= 1%
 Handling Power capacity with crossover 3.15kHz, 12dB/oct  
 60W
 Short term power (10mS)
 220W
 Znom (Electrical Impedance)
 4 ohm
 Re (DC resistance)
 0.07 ohm
 Le (Voice coil inductance @ 1kHz)
 85 H
 Ribbon thickness
 9.5 m overall
 Magnetic induction in the gap
 0.42 T
 Mmd (Mass of the ribbon)
 15 mg
 Sd (Radiating surface)
 6 cm^2
 Max. undistorted power through  the matching transformer 
 39W at 2.5kHz
 Lowest recomended cutoff frequency of the crossover 
 3.15 kHz
 Weight
 0.78 kg
 NdRL 81 MkII Technical Data
 Frequency response (-3dB, ripples less than 2dB)
 2.8 - 40kHz
 Sensitivity (1W (2.83V), 1 meter)
 89 db (+/- 1dB)
 THD (DIN 45500)
 </= 1%
 Handling Power capacity with crossover 3.15kHz, 12dB/oct  
 60W
 Short term power (10mS)
 220W
 Znom (Electrical Impedance)
 8 ohm
 Re (DC resistance)
 0.22 ohm
 Le (Voice coil inductance @ 1kHz)
 200 H
 Ribbon thickness
 9.5 m overall
 Magnetic induction in the gap
 0.42 T
 Mmd (Mass of the ribbon)
 15 mg
 Sd (Radiating surface)
 6 cm^2
 Max. undistorted power through  the matching transformer 
 39W at 2.5kHz
 Lowest recomended cutoff frequency of the crossover 
 3.15 kHz
 Weight
 0.78 kg
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