The 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.
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/cm2).
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/cm2 = 10 microbars = 94 dB SPL.
