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Sennheiser Orpheus HE90

Sennheiser Orpheus HE90 made their initial debut in 1991 and was immediately recognized in audiophile circles as the most innovative headphone system ever made. The Orpheus system comes in two parts, the electrostatic headphone (HE 90) and the headphone amplifier (HEV 90).
From Sennheiser:

“With the boldly ambitious mission to build the best headphones in the world, Sennheiser developers once again set to work – and once again exceeded all expectations of the audio sector with these electrostatic headphones and their impressive tube pre-amplifier. Two platinum-coated diaphragms vibrate between gold-coated glass electrodes. A 500 volt tube amplifier provides enough power to allow the Orpheus to fully unleash its sound. Due to the extremely complex technology involved, the Orpheus was produced in a limited edition of just 300 units.”

These legendary headphones still remain the ultimate benchmark for audiophile listening and it’s something you would want prominently displayed in your living room, because it’s a work of art. The Orpheus originally carried a retail pricetag of $16,000 that price increased somewhat over time. A more detailed review can be read on Stereophile.


Sennheiser Orpheus HE90 Headphone Specifications:

Frequency response: 7-100,000 Hz (-10 dB); 14-85,000 Hz (- 6 dB); 25-75,000 Hz (- 3 dB)
Frequency range: diffuse field equalized
Transducer principle: electrostatic
Ear coupling: circumaural
Contact pressure: 4.6 N
THD at SPL of 110 dB (94 dB) < 0.1 % (< 0.01 %)
Nominal sensitivity: (V = 100 V) ≥ 98 dB/1 kHz
Polarisation voltage: 500 V
Weight (without cable): 365 g
Connector: 5-pin HV plug
Connection cable: 3 m, 6-core; OFC copper cable with gold-plated contacts
Dimensions: 19 x 10 x 21.5 cm

Sennheiser Orpheus HEV-90 Amplifier Specifications:

Frequency response: 10 – 20,000 Hz (- 0.25 dB)
THD (1 kHz) < 0.01 %
Unweighted S/N ratio ≥ 80 dB
Sensitivity/impedance: 10 kΩ
Talk-over muting: (1 kHz) ≥ 80 dB
Output voltage :400 Veff
Line inputs:
– (switchable) optical, digital (Toslink)
– co-axial, digital (RCA phono)(automatic recognition of incoming sampling frequency)
– co-axial, analogue(RCA phono)
Outputs for 2 HE 90 headphones
Weight approximately: 13 kg
Dimensions: 53 x 34 x 15.5 cm