User manual SENNHEISER UNIPOLAR 2000

[. . . ] This headphone has been developed lor the highest possible sound quality combined with excellent wearing comlort. The unit IS still easy to use while containing several special leatures. We are sure that you will immedlately appreciate these leatures and the unusual homogeneous and transparent sound reproduction when you start using this headphone. [. . . ] 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. 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. The headphone operation with such ampliflers is perlectly sale when during on-off or program switching the volume control is in a minimum position and the headphone's levells brought up after such operations. [. . . ] Delective housings, connecting cables and connectors are immediately to be taken out 01service and repaired by an authorized service techniclan I 3. Unauthorized opening of headphone shells or the supply unlt voids warranty and may Impair the performance Sound pressure level at 5 V Max. Maln support crreumaural vra acoustlcally and leatherette cushlon at the head Ear cushlon wrthout pressure N (460 p) 22000 Hz 4 8Q 103 dB (: 110 dB at 1 kHz (6. [. . . ]