General
The "unipolar 2000" is an "open-alre@" electrostatic stereo-headphone with electret transducer. 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.
Description
This electrostatic headphone system contains two basic parts: the headphone "unipolar 2000" and the supply unit
HER 2000. The supply unit delivers the necessary stepped-up audlo voltage to operate the transducers in the
headphone. Without this supply unit the headphone cannot be used. The headphone must never be connected to
any other source.
Headphone: The headband 1 is litted wlth an adjustable headcushion 2 and can be easily set to a comlortable
position lor the listener by means 01the cushion adjustment 3 The two headphones shells are colorcoded by cable
sleeves 4 and 5: red = right channel, yellow = lelt channel. The connector 15 is to be Inserted into the sockets 11or
12 on the. supply uni!.
Supply unit: The headphone unit HER 2000 6 can leed two headphones "unipolar 2000" The headphone plug 15
may be connected to either 01the two output sockets 11 of12 I1aheadphone is inserted into the socket 12then its
volume only depends upon the setting of the volume control 01the Ieeding amplilier. I1the headphone - or a
second headphone - is connected to socket 11 the loudness 01this output may be pushbutton attenuated by
means 01the three buttons 8 When the button "0 dB" is pressed down both headphones are equally loud. I1you
push "- 6 dB"- 12 dB" the volume at the output 11 is reduced by the selected value. This way two listeners may
enjoy headphone listenmg at different levels.
Another leature of the supply unit is the pushbutton 7which allows to select between loudspeaker and headphone
operation. In the down position the headphones are operative and, if the button is released, the connected loud-
speakers are in the circui!.
The excellent sound quality 01this electrostatic headphone system "unipolar 2000" allows to detect the linest
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 inthe headphones are effectively protect-
ed against overload through electrical measures in the supply unlt and can thus hardly be destroyed even during
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 4fl) per channel. HiFi ampilliers upto apower 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. Very high transient
voltages are capable to activate the protection circuit irreversibly This protective condition can only becorrected by
an authorized service technlcian.
Important notice:
Electrostatlc headphones operate with high drive voltages Great care has been taken to manulacture a perlectly
sale headphoneandconnectioncables.PleaseobservethelollowingIn ordertoalwayskeepyourequipmentIn
this safe condltlon.
1. Never use any sharp pointed obJectsto 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. Unauthorized opening of headphone shells or the supply unlt voids warranty and may Impair the performance
and salety01the equipmentI
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Connection to your HiFi-system
1. Connection to DIN-Ioudspeaker sockets
Plug the connectors 13 into the loudspeaker outlets 01your amplilier or receiver. Red = right channel, yellow = lelt
channel. Your loudspeaker cables are then simply connected to the rear of the plug 13. By means of the push-
button 7 on the supply unit 6 you may now select either loudspeaker or headphone operation (see lig.1)
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2. Connection to loudspeaker screw-on terminals
The connection cable 14 01the "unipolar 2000 Set X" supply unit is litted with cable lugs and insulated clip-on
connectors. 11your amplilier is litted with such terminals connect as shown In lig 2 or fig. 3 as lollows
a) Amplifiers with several switchable output groups:
This connection scheme (Iig. 2) can be optimally used lor the headphone only ilthe secondary outputs 01the ampli-
lier have no internal series resistors I1your resistors are inthe amplilier's output circuit slight roll-off atthe very low
and very high end may result, which may not be noticeable by ear. 11this is undisered the headphone should be
connected as indicated in the lollowing scheme b). This means that loudspeaker and headphones should be con-
nected to one 01the outputs and the switching facilities 01the supply unit
are used.
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b) Amplifiers with single stereo screw-on terminals:
When the supply unit and the loudspeakers are connected asshown in lig.3 the mode 01operation -Ioudspeaker
or headphone - may be selected by the pushbutton 7. If only the "unipolar 2000" is connected to the ampillier
the black and the grey leads are not used and remain unconnected. Pushbutton 7 must then, 01course, be in the
down position.
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eleetrostatie HI FI-stereo-headphone
Sound coupllng to the ear
maln support crreumaural vra acoustlcally
and leatherette cushlon at the head Ear
cushlon wrthout pressure
N (460 p)
22000 Hz
4 8 Q
103 dB (:
110 dB at 1 kHz (6.3 Pa)
25 VRMS to 156 Watts at 4 Q) !ransient eondition
35 VRMS to 306 Watts at 4 Q) contlnuous
,0;01 %
3m
15 m
75 x 65 x 184 mm
appx 345 9
appx 1600 9
Headband pressure
Sound pressure level at 5 V
Max. sound
Max
THD at 1000 Hz/110dB
Cable length headphone
Cable length supply uni!
DimenSions HER 2000
Welght headphone
Welght supply unr!
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