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General
The "unipolar 2002" is the world's lirst electrostatic headphone with a 2-way system without diplexer. Through
the concentrically arrangement 01 both systems in one plane the distortlonless reproduction 01 an unusual wide
Irequency range is achieved.
Another leature 01the headphone is the exceptional high efficiency, so that a high reproduction volume can be
adjusted easily.
Description
This electrostatic headphone system contains two basic parts: the headphone "unipolar 2002" and the supply unit
HER 2000. The supply unit delivers the necessary stepped-up audio 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 fitted with an adjustable headcushion 2 and can be easily set to a comfortable
position for the listener by means 01the cushion adjustment 3 .The two headphone shells are colorcoded by cable
sleeves 4 and 5 : red = right channel, yellow = left channel. The connector15 is to be inserted into the sockets 11or
12 on the supply unit.
Supply unit: The headphone unit HER2000 6 can leed two headphones "unipolar 2002". The headphone plug 15
may be connected to either of the two output sockets 11 or 12 If a headphone is inserted into the socket 12 then its
volume only depends upon the setting 01the volume controlaI the Ieeding amplilier. If the headphone - or a
second headphone - is connected to socket 11 the loudness 01 this output may be pushbutton attenuated by
means of the three buttons 8 When the button "0 dB" is pressed down both headphones are equally loud. II you
push "-6 dB" "-12 dB" the volume atthe output 11iis reduced by the selected value. This way two listeners may
enjoy headphone listening at different output levels.
Another feature of the supply unit is the pushbutton 7 which allows to select between loudspeaker and headphone
operation. In the down position the headphones are operative and, il the button is released, the connected loud-
speakers are in the circuit.
The excellent sound quality of this electrostatic headphone system "unipolar 2002" allows to detect the finest
sound structures and nuances. In order to maintain this high quality even at high sound pressure levels the supply
unit HER 2000 is litted wlth two LEDs to monitor the beginning of an overload condition. The indicator 10
monitors the left and 9 the right channel. These diodes start to light up when the laintest distortlon appears which
is still undetectable by ear. This starting point is at approximately 117 dB peak sound pressure level.
We would like to point out that volume levels of that magnitude are already considered dangeraus to the ear by
hearing specialists when listening over an extended period of time. Therefore we recommend to set your peak
volume level always to a value below the point where the
LEDs light up. This also eliminates the generation of
any undesired additional distortion in the headphones The transducers in the headphones are effectively protect-
ed against overload through electrical measures in the supply unit and can thus hardly be destroyed even during
langer lasting overload periods. The audible effect of an overload is that the headphones reproduction volume is
reduced to avery low value. The headphones resume normal operation after a few seconds when the cause for the
overload condition has been removed.
For normal operation and maximum volume the "unipolar 2002" must be connected to apower amplifier of at least
15 Watts at 8 Q (30 Watts at4 Q) per channel. HiFiampliliers up to a power output of 150 Watts may be used without
danger for the headphone systems of the headphones since the protection Clrcuit mentioned above becomes
effective at extreme overload conditions.
Caution should be exercised when high powered super ampliliers above 150 Watts per channel are used. The
headphone operation with such amplifiers is perfectly safe when during on-off or programs switching the volume
control is in a minimum position and the headphone's level is brougt up after such operations. Very high transient
voltages are capable to activate the protection circuit irreversibly. This protective condition can only be corrected by
an authorized service technician.
Important notice:
Electrostatic headphones operate with high drive voltages. Great care has been taken to manulacture a perfectly
sale headphone and connection cables. Please observe the following in order to always keep your equipment in
this safe condition:
1. Never use any sharp pointed objects to pierce headphone parts or connection cables or any part of the supply
unit!
2. Defective housings, connecting cables and connectors are immediately to be taken out 01service and repaired
by an authorized service technician!
3. Unauthorized opening of headphone shells or the supply unit voids warranty and may impair the performance
and safety of the equipmentl
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Connection to your HiFi-system
1. Connection to DIN-Ioudspeaker sockets
Plug the connectors 13 into the loudspeaker outlets 01your amplifier or receiver. Red = right channel, yellow = left
channel. Your loudspeaker cables are then simply connected to the rear 01the plug 13 . By means of the push-
button 7 on the supply unit 6 you may now select either loudspeaker or headphone operation (see fig. 1)
1
\
2. Connection to loudspeaker screw-on terminals
The connection cable 14 of the "unipolar 2002 Set X" supply unit is fitted with cable lugs and insulated clip-on
connectors Ifyour amplifier is fitted with such terminals connect the supply unit as shown in fig 2 or Iig 3 as lollows:
a) Amplifiers with several switchable loudspeaker output groups:
This connection scheme (Iig. 2) can be optimally used for the headphone only if the secondary outputs 01the ampli-
lier have no internal series resistors. If resistors are in the amplifier's output circuit slight roll-off at the very low
and very high end may result, wh ich may not be noticeable by ear. If this is undisered the headphone should be
connected as Indlcated in the lollowing scheme b). This means that loudspeaker and headphones should be con-
nected to one of the outputs and the switching facillty of the supply unit is used.
b) Amplifiers with single stereo screw-on terminals:
When the supply unit and the loudspeakers are connected as shown In fig. 3 the mode of operation - loudspeaker
or headphone- maybeselectedby the pushbutton7 . II onlythe "unipolar2002" is connectedtothe amplifier
the black and the grey leads are not used and remain unconnected. Pushbutton 7 must then, of course, be in the
down position.
1
)
Transducer
Frequency response
Matchlng Impedance
Sound pressure level at 5 V
Max. sound pressure level
Max tolerable voltage applled
THDat 1000 Hz/110 dB
Sound coupling to the ear
electrostatlc
16 22000 Hz
4 - 8 Q (Ioudspeaker output)
109 dB
117 dB 8t 1 kHz
~5 VRt;!S
~ 0,1 m
ClrcumaLJra!, via acoLJstically closed leatherette cushlon
wlthout ear contact
appx. 4,5 N (460 pi
3m
1,510
75x65x184mm
appx. 345 9
appx. 1600 9
Headband pressure
Cable length headphone
Cable length supply unlt
Dimensions HER 2000
Welght headphone
Welght supply unlt
We reservethe right to alter specitications, in partlcular with regard 10technicallmprovements.