User manual SENNHEISER UNIPOLAR 2000

[. . . ] Your loudspeaker cables are then simply connected to the rear of the plug 13. By means of the pushbutton 7 on the supply unit 6 you may now select either loudspeaker or headphone operation (see lig. This electrostatic headphone system contains two basic parts: the headphone "unipolar 2000" and the supply unit HER 2000. [. . . ] This way two listeners may enjoy headphone listen mg at different levels. Another leature of the supply unit is the pushbutton 7 wh ich allows to select between loudspeaker and headphone operation. In the down position the headphones are operative and, if the button is released, the connected loudspeakers are in the circui!The excellent sound quality 01 this electrostatic headphone system "unipolar 2000" allows to detect the li nest sound structures and nuances In order to maintain th, s high quality even at high listening levels the supply unit HER 2000 is litted with two indicator diodes to monitor the beginning 01an overload condition. the Indicator 10 monitors the left and 9 the right channel. These diodes start to light up when the laintest distortion appears which is still undetectable by ear. This startmg point is at approximately 113 dB peak sound pressure level. We would like to point out that volume levels 01that magnitude are already considered dangerous to the ear by hearing specialists when listenlng over an extended period of time. Therelore we recommend to set your peak volume level always to a value below the starting point 01the Indicator lights. This also eliminates the generation 01 any undesired additional distortion in the headphones. The transducers in the headphones are effectively protected against overload through electrical measures in the supply unlt and can thus hardly be destroyed even du ring Ionger lasting overload periods. The audible effect 01an overload ISthat the headphones become very weak m volume since the drive voltage ISreduced. The headphones resume normal operation after a lew seconds when the cause for the overload condition has been removed. For normal operation and maximum volume the "unipolar 2000" must be connected to apower amplifler 01at least 15 Watts at 8 n (30 Watts at 4 fl) per channel. HiFi ampilliers up to a power output 01150 Watts may be used without danger lor the driving cells 01the headphones slnce the protection circult mentioned above takes care 01extreme overload conditions. Caution should be exercised when high powered super ampliliers above 150 Watts per channel are used. [. . . ] Pushbutton 7 must then, 01course, be in the down position. Sound coupllng to the ear Electrostatlc headphones operate with high drive voltages Great care has been taken to manulacture a perlectly Never use any sharp pointed obJects to pierce headphone parts or connection cables or any part 01the supply unlt I 2. Delective housings, connecting cables and connectors are immediately to be taken out 01service and repaired by an authorized service techniclan I 3. [. . . ]