Neumann.Berlin fet 80R (i) Owner's manual

Neumann-Information 1841
NOV. I 984
Operation of NEUMANN fet 80R(i) microphones in conjunction with unba-
lanced or Center tap grounded inputs
The microphones of the fet 80 R (i) series are Phantom powered from
48 Vdt according to IEC 268-15A/DIN 45, 596.
In Phantom powering both modulation conductors of the microphone cable as
-weil as the modulation leaving the power supply are at the powering voltage
potential of +48 Vdt.
For professional balanced and floating amplifiers and
console inputs this is of no consequence. However when such Phantom powered
microphones are
connected to inputs which have side or the Center tap
grounded, the powering voltage is shorted out and no Operation is possible.
For Center tap grounded equipment with an input transformer (e.g.some NAGRA
NAGRA recorders), this Center tap ground tan virtually always be discon-
nected without causing any negative operational results.
For connection af NEUMANN fet 80 R
microphones to unbalanced inputs,
there are the following possibilities:
1. Microphone and power supply may be operated without any alterations even
into unbalanced or Center tap grounded inputs, if a high quality cable
transformer (1 :l turns ratio) of the AT 8/1 (i) type is inserted into
the modulation line.
Since there are numerous types of microphone input connectors, this
transformer is supplied with stripped and tinned secondary leads only.
A specific connector will be attached to the secondary on special Order
and at additional price.
The maximum input Signal capability of the AT 8/1 (i) is 300 mV at 40 Hz;
frequency range is 30...16,000 Hz. Fig. 1
Bu 1 5u 1 +--20cm
4 b-- 30cm ---+
INTERNATIONAL DIN PRIMARV SEKUNDARV
i .
- MICROPHONE
(150.. 250a.h)
Bu 1 Bu 1
;NTEANATIONAL DIN
0
ty$ AT811 i
Soldering side vietq
Fiq. 1
GN7
CHARLOTTENSTRASSE 3 . D-l000 BERLIN 61 I POSTFACH 610469 . TELEGRAMM: NEUMANNACUSTIC
TELEFON: [phone] . TELEFAX: (030) 25993-108 . TELEX: 184595 NEUAK D Printed in Germany

2. Microphone and power supply may be converted to unbalanced Operation in
the field through a minor alteration. This Change is
recommebded if the
microphone is to be used exclusively with unbalanced inputs such as
semi-professional or home equipment. Fig. 2...5
Switchcraft
A3M
t- .-
(DIN L152t 1
Standard, balanced configuration of Neumann microphone Outputs. Fiq* 2
Switchcroft
A3M I DIN L 152t)
1 f-*-
(2)
Fiq. 3 Unbalanced connections.
1. Wire heretofore connected to pin 2 (+), remains connected to pin 2
(now modulation alone).
2. Wire heretofore connected to pin 3 (-> is to be resoldered to pin 1
without removing the wire already connected there.
3. Remove the Phantom powering resistors (2 x 6.8 kohm).
4. Move the wire previously connected to the junction of these resistors
to pin 3.
The circuit then conforms to IEC 268-12.

Far microphones equipped with connectors per DIN 41524 (Binder, Mini-
Tuchel), the following changes are necessary:
1. Wire heretofore soldered to pin 3 (-1 is to be resoldered to pin. 2
without removing the wire already connected there.
2. Wire heretofore connected to pin 1 (+> is to bt-: resoldered to pin 3.
3. Remove the Phantom pawering resistors.
4. Install a new wire from the junction of these resistors to pin 1.
The circuit then corresponds to DIN 45594 Type L.
The IC 3, IC 4, KT 1 tiicrophone Cables require no changes.
Conversion of the N 452 i, BS 945 i etc. Power Supplies:
+L8V-
.-
+4--
6k8
J
Switchcraft
A3F
1-
6k8 T
I
1
x
/
-t:
I
ov
T
1
i’-
A3M
.-
#
.
3 ov
.
+ 2 w Modulation
-&=l OV, Schirm
L,-
Shield
i
Fig. 4
11)
121
11)
131
(2)
1. Remove and discard the 6.8 kohm resistor soldered to pin 2.
2. Remove and discard the wire heretofore connected to pin 3 (output
side).
3. Strap pin 1 and pin 3 together (output side).
For microphones equipped with connectors per DIN 41524, the following
applies :
The pin numbers of Figs, 1, 2, 3 correspond to the pin numbers 2, 3, 1
in this order (sec also the schematic supplied with your equipment) .

Audio Modulation cable to the amplifier, tape recorder etc. equipped
with unbalanced input:
i DIN‘L152L 1 Switchcraft
w Modulation
Schirm
Shield
Fig. 5
3. Should the use of a transformer as recommeded in example #l not be desi-
rable or the microphone put out’modulation voltages beyond those permis-
sable for the AT 8/‘l (i) transformer, then you may block the 48 Vdt phan-
tom power from your input through the use of blocking capacitors:
Switchcroft
-iz3L-dbfF
‘6k86k8 II
‘< 2‘< 2
6k86k8 ..
11
2x +2x + ;;
+L8V-+L8V- lOOp163VlOOp163V
T
T I
Fig. 6
( DIN L152L 1
(3)
11)
(2)
;
(3)
Pin numbers in parentheses refer to microphones equipped with connectors
according to DIN 41524 (Binder or Amphenol-Tuchel).
Errors excepted.
Subject to changes.