SCHOEPS CCM - Manual (Page 7)

SCHOEPS GmbH · Spitalstr. 20 · D-76227 Karlsruhe (Durlach) · Tel: +49 (0)721 943 20-0 · Fax: +49 (0)721 943 2050
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Block Diagram of the CCM Compact Microphones
7
Technology
microphone amplifier
acoustic transducer
Pin assignment of the XLR-3M output con-
nector of CCM microphone amplifiers:
Pin 1: screen (GND)
Pin 2: +phase
Pin 3: –phase
Bottom view
(as the pins are seen)
1 2
3
Impedance converter
Output stage
DC/DC converter
Regulator
EMI filter
3 1 Scr
een
-Phase +Phase
XLR-3 Connector
2
3 1 2
3 1 2
Microphone cable (adapter cable Lemo/ XLR-3M
Phantom powering
U
s
= +48 V
R
s
= 6.8 k
Ω
R
s
= 6.8 k
Ω
Preampli
-
fier
,
recorder or mixing desk
* *
**
**
∼ ∼
scr
een
-phase +phase
XLR-3 connector
XLR-3 connector
and between 15 and 21 mA DC for P12. Note: W
e
ll-designed phantom power supplies must
tolerate at least a
temporary short cir
cuit without damage; an unbalanced connection
(w
h
ic
h
i
s
o
cc
a
sionally necessary) would cause the same curr
ent to be
d
ra
w
n
.
To
be safe, however
, do not leave the short cir
cuit in place
longer than necessary
.
2) Measur
e the DC voltages on the modulation leads with a micr
o-
phone connected, e.g. by opening the connector shell of the cable. The tw
o
voltages (fr
o
m pin 2 and pin 3 to pin 1) must be identical. Th
e
y
should be about 34 V
olts (minimum = 30 V
olts). For P12 this is 8.3
V
olts (minimum 7.3 V
olts).
3) For P48, use a
SCHOEPS
PHS 48 tester
. Plug it in; if the LED glows and
stays lit, all is well.
+Phase: an excursion of the diaphragm towar
ds the back electr
ode (posi-
tive pr
essur
e phase) leads to a positive signal at this pin
*Matched (i.e. matching tolerance of only 0.7%), see page 5 ** Her
e ar
e thr
ee simple methods for verifying corr
ect phantom powering.
These measur
ements should be made at an unused input. Reduce the
channel gain to the minimum to pr
otect the loudspeakers, etc. If micr
o-
phones ar
e connected to other inputs at the same time, no substantial
dif
fer
e
nce should occur in the r
e
sults.
1. Measur
e the open-cir
cuit voltage between gr
ound (pin 1) and either pin
2 or pin 3 of the XLR input. Given the permitted tolerances, this voltage should be between 44 and 52 VDC for P48, and between 11 and 13 VDC for P12. Then, measur
e the short-cir
cuit curr
ent between gr
ound
(pin 1) and either pin 2 or pin 3 of the XLR input. Given the permitted tolerances, this curr
ent should be between 5.9 and 8.5 mA DC for P48,