Unipolar 2000


Main Details
Maker Sennheiser Brand
Form Factor Headphone - Circumaural
Signal Path Analog Hardware
Made In Germany
Date Produced 1977-19??
Weight 345 g (headphone only)
Frequency Response 16-22000 Hz
Notes Supply unit's model no.: HER 2000

Sennheiser's retrospective appraisal of their product:
"A further milestone followed when Sennheiser engineers for the first time combined the principle of open headphones with that of electrostatic transducer technology. Sennheiser’s launch of the unipolar 2000 model in 1977 caused a sensation in the audio world. Its principle was once again an innovation in audio technology. In the electrostatic transducer, a high voltage is applied to two mesh-like electrodes. As in a loudspeaker, this voltage causes a coated foil diaphragm to vibrate in time with the audio signal. This results in an extremely fine resolution and low total harmonic distortion. “Its frequency curve has a relatively deep curvature from 2 to 4 kHz. This is one of the reasons why these headphones generate an extremely spacious, detailed, transparent, airy and nevertheless powerful sound image in unprecedented quality," was how one audio magazine ‘Hifi-Stereofonie’, sang the praises of the new headphones."
Additional Specifications
Principle open electrostatic Hi-Fi-stereo-headphone
Transducer electrostatic
Sound coupling to the ear "open-aire" principle, main support circumaural via acoustically open supporting ring and leatherette cushion at the head. Ear touching foam cushion without pressure.
Headband pressure appx. 4.5 N (460 p)
Matching impedance 4-8 Ω loudspeaker output
Sound pressure level at 5V 103 dB (2.8 Pa)
Max. sound pressure level 110 dB at 1 kHz (6.3 Pa)
Max. tolerable voltage applied 25 VRMS corresponding to 156 W at 4 Ω, transient condition
Max. tolerable voltage applied 35 VRMS corresponding to 306 W at 4 Ω, continuous
THD at 1000 Hz/110 dB ≦ 0.1 %
Cable length headphone 3 m
Cable length supply unit 1.5 m
Dimensions HER 2000 75x65x184 mm supply unit
Weight supply unit appx. 1600 g


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