Schoeps M? Series User Manual page 6

Phantom Powering
Fig. 1
Input with transformer
(or balanced, floating trans-
formerless input)
Fig. 2
To add phantom powering
to a balanced, grounded,
transformerless input, capa -
citors must be inserted into
the signal lines and polariza-
tion resistors provided as
shown.
Fig. 3
Parallel powering;
with parallel powering there is low-impedance
DC across pins 2 and 3. This can damage
dynamic microphones, especially ribbons.
be checked to verify its suitability for profes-
sional work with SCHOEPS microphones. On
page 8 a method is described for checking a
phantom supply quickly and easily.
For P12 the standard allows a current of
15 mA. A SCHOEPS CMC 3 will draw 11 mA
while a CMC 6 needs 8 mA at 12 Volts.
Fig. 2 shows a bal an ced but groun ded am -
pli fier in put. In this case eit her a trans for mer
(see fig. 1) or ad di tio nal ca pa ci tors ha ve to be
in ser ted in the au dio li ne.
Unbalanced Operation
Unbalanced operation of CMC microphone
amplifiers is not recommended; both noise and
vulnerability to interference will be increased.
6 SCHOEPS GmbH · Spitalstr. 20 · D-76227 Karlsruhe (Durlach) · Tel: +49 721 943 20-0 · Fax: +49 721 943 2050
2 (4)
+ phase
XLR-3-
microphone
connector
- phase 3 (5)
1
with XLR-5
(stereo microphones)
2 (4)
+ phase
XLR-3-
microphone
connector
- phase 3 (5)
1
XLR-3
connector
screen
shield
powering
I
/2
R
S
I
R
S
I
/2
cable
P48: U = 48 V ± 4 V; R = 6,8 kW*,
S S
P12: U = 12V ± 1V; R = 680 W*,
S S
* see note in the text concerning tolerances
R
S
screen
shield
U
R
S
cable
powering
shield
cable
** Tolerance ca. 5%; precise
matching is not critical.
If possible, an unbalanced input should be bal-
anced with a high-quality microphone input
transformer. That will also allow the signal leads
from the microphone to be balanced, for best
rejection of interference.
If such an arrangement is not possible, how-
ever, a CMC microphone may be operated in
unbalanced mode by taking the signal from
pin 2 via a coupling condenser with a value as
shown in Figure 2 above. The signal from pin 3
must be left unconnected; do not short it to
ground. This "unbalancing act" must occur
between the power supply and the preamplifier
input, however, since naturally all three pins
of the microphone must still connect to its
phantom or parallel power supply.
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U
S
input
I
= 10 mA
max.
I
= 15 mA
max.
*
C
S
* *
R R
R
*
C
input
* recommended values:
C: 100 μ F, 63V; R: 22k Ω , 1%
**
Ohms
**
Ohms
z.B.
10 kOhm