T
he CM-150 is a ½-inch-diameter
(12.7-mm), omnidirectional electret-
condenser microphone. It is intended
for professional recording, free-field mea-
surement and sound-level measurement.
Because of its pre-aged titanium diaphragm,
the CM-150 is extremely stable over a wide
range of environmental conditions.
The CM-150 has a very flat, wide-range fre-
quency response. The mic is supplied with a
proof-of-performance sheet, which shows
frequency response and sensitivity. This
information can be used to calibrate the mi-
crophone. The mic capsule grille fits into a
Bruel & Kjaer 4220 pistonphone or similar
microphone calibrator.
When used for recording, the CM-150
sounds natural and accurate. It preserves
the delicate timbre of acoustic instruments,
yet can reproduce all the power of a pipe
organ. The off-axis response is also smooth,
so any leakage picked up has little colora-
tion.
Self-noise is low, permitting clean record-
ings — especially with close miking. The
mic can handle very loud sounds (127 dB
SPL) without distortion. It is protected
against static and RFI. The output is bal-
anced, low impedance, which allows long
cable runs without hum pickup or high-fre-
quency loss. Powering is by 18-48 volt
phantom power.
An included foam windscreen reduces wind
noise outdoors.
Architects’ and Engineers’ Specifications
The microphone shall be a Crown CM-150
or equivalent. It shall be an omnidirectional
electret-condenser type powered by 18-48
volt phantom power. Frequency response
shall be uniform from 20 Hz to 20,000 Hz.
Open-circuit sensitivity shall be 10.5 mV/Pa.
Maximum SPL for 3% THD shall be 127 dB
with 48-volt phantom power. Self-noise shall
be 19 dB SPL A-weighted. Impedance shall
be 240 ohms balanced. The mic shall be
compatible with ½-inch (12.7 mm) indus-
try standard calibration. The Crown CM-
150 is specified.
PROFESSIONAL OMNIDIRECTIONAL
CONDENSER MICROPHONE
CM-150
Specifications
Element:
Electret condenser.
Frequency response (typical):
20 Hz to 20 kHz
±1.5 dB (see Fig. 1).
Polar pattern:
Omnidirectional (see Fig. 2)
Impedance:
150 ohms, 240 ohms actual, bal-
anced. Recommended minimum load imped-
ance 1000 ohms.
Open circuit sensitivity (48 volt supply):
10.5
mV/Pa* (–39.5 dB re 1 volt/Pa) nominal.
Power sensitivity:
–39.5 dB re 1 mW/Pa.
Equivalent noise level (self-noise):
19 dB SPL
typical, A-weighted (0 dB = .0002 dyne/cm
2
).
S/N ratio:
75 dB at 94 dB SPL.
Maximum SPL for 3% THD:
127 dB with 48V
phantom power.
Output connector:
3-pin male XLR type.
Power:
18-48 volt phantom power, positive volt-
age on pins 2 and 3 with respect to pin 1.
Current drain:
2.7 mA.
Polarity:
Positive (inward) pressure on the dia-
phragm produces positive voltage on pin 2 with
respect to pin 3 of the output connector.
Materials:
Brass handle, stainless steel mic cap-
sule, titanium diaphragm.
Finish:
Satin black handle and chrome mic cap-
sule.
Dimensions:
See Fig. 3.
Weight:
4.48 ounces (127 grams).
Included accessories:
WS-15 foam wind-screen,
carrying pouch, ASA-4 stand adapter and vinyl
grille protector.
Optional accessories:
Crown PH-4B phantom
power supply (4 channels, AC powered). Crown
PH-1A phantom power supply (1 channel, bat-
tery or AC powered).
*1 pascal = 10 dynes/cm
2
= 10 microbars = 94 dB
SPL.
Fig. 1
5 kHz
10 kHz
FRONT
REAR
-20
-15
-10
-5
-0
60˚
90˚
120˚
150˚
180˚
210˚
240˚
270˚
300˚
0˚
30˚
330˚
20 kHz
OMNI 20 Hz-2 kHz
Frequency in Hz
Frequency Response
Fig. 2
