Crown Audio Microphone CM 311A User Manual

POLAR  
PATTERN  
DIFFEROID HEAD-WORN  
CONDENSER MICROPHONE  
Features  
• Full, clear, distortion-free sound  
• Outstanding gain-before-feedback and isolation  
• CM-311A has battery/phantom belt pack  
• CM-311AE connects to most wireless transmitters  
CM-311A  
CM-311AE  
esigned for touring and live-sound applica-  
tions, the Crown® CM-311A is a rugged  
Specifications  
Transducer type: Electret condenser.  
D
head-worn microphone with unequalled  
performance. It sounds like the best handheld micro-  
phones—full, clear, and distortion-free, even with the  
loudest singers.  
Frequency response (typical): 50 Hz to 17,000 Hz  
(see Fig. 1).  
Polar pattern: Cardioid (see Fig. 2).  
Impedance: CM-311A, 75 ohms balanced. CM-311AE,  
6 kilohms unbalanced.  
Recommended load impedance: CM-311A, 1000  
ohms or greater. CM-311AE, 10 kilohms.  
Open-circuit sensitivity, typical, close-talking: CM-  
311A, 4 mV/Pa* (–48 dB re 1V/Pa), CM-311AE,  
1.25 mV/Pa (–58 dB re 1V/Pa).  
Power sensitivity, typical, close-talking: CM-311A:  
–42.5 dB re 1 mW/Pa*, CM-311AE: –71.5 dB re 1  
mW/Pa.  
Optional accessories: PH-1A phantom power  
supply (1 channel, AC-adapter powered). WS-  
14 accessory windscreen.  
The CM-311A is the latest version of the Crown’s  
proprietary Differoid® technology. Its cardioid pickup  
pattern rejects sounds from the rear, such as floor  
monitors. Its noise-canceling ability rejects sounds at  
a distance, such as instruments on stage and crowd  
noise. This results in the CM-311A having outstand-  
ing gain-before-feedback and isolation.  
*1 pascal = 10 dynes/cm2 = 10 microbars = 94 dB  
Fig. 1  
Frequency Response  
Lightweight and comfortable, the mic’s headband and  
boom adjust to fit any singer. An included pop filter  
greatly reduces breath noise and pops. Because of  
the boom’s unique behind-the-ear design, it does not  
cover up the singer’s face.  
Equivalent noise level (self noise): 26 dB SPL typi-  
cal (0 dB = 0.0002 dyne/cm2), A-weighted.  
S/N ratio: 68 dB at 94 dB SPL.  
Maximum SPL: CM-311A, 148 dB SPL produces 3%  
THD. CM-311AE, 140 dB SPL with 3V DC, 148 dB  
SPL with 9V DC.  
Operating voltage: CM-311A, 9V DC internal alkaline  
battery or 18-48V phantom power. CM-311AE,  
3–9V DC from the transmitter’s battery.  
Polarity: Positive pressure on diaphragm produces  
positive voltage on CM-311A XLR pin 2 with  
respect to pin 3, and on CM-311AE shield with  
respect to white lead.  
Current drain: CM-311A, 6.5 mA nominal.  
CM-311AE, 0.27 mA nominal.  
Battery life: CM-311A, 85 hours. CM-311AE, approxi-  
mately equal to transmitter battery life.  
Two models are available: CM-311A and CM-311AE.  
The CM-311A is powered by a 9V battery or phantom  
power. It has a battery belt pack with an on/off switch,  
a programmable mic on/off switch, and a “Mic On”  
LED. The CM-311AE is a pig-tail version allowing you  
to connect it to most wireless transmitters.  
Frequency in Hz  
Fig. 2  
Polar Response  
NOTE: Putting an XLR connector on the CM-311AE  
and connecting to a mic input with phantom power  
WILL damage the mic element. For wired applica-  
tions, use the CM-311A.  
How to adjust for best fit and to prevent boom  
bounce  
Operating temperature range: –10° to +50° C, or  
–14° to +122° F.  
Off-attenuation: 70 dB.  
Note: To get the maximum performance out of this  
microphone, take the time to adjust it to fit correctly.  
Output connectors: CM-311A, 3-pin pro audio (XLR  
type). CM-311AE, supply your own to match your  
transmitter.  
Cables (CM-311A): 2-conductor shielded, unbalanced  
cable, 42-inches (106.68 cm) from headband to  
battery pack. Use 2-conductor shielded mic cable  
(not included) between XLR connector and mixer  
mic input.  
Cable (CM-311AE): In-line with this cable is a small  
circuit module that equalizes the microphone  
signal. Cable is 42-inches (106.68 cm) long from  
headband to module, 12-inches (30.48 cm) from  
module to cable end. 2-conductor shielded unbal-  
anced cable, unterminated.  
Materials: High-impact plastic mic housing, brass  
boom, steel wire headband, high-impact plastic and  
steel battery pack.  
For best results, the CM-311A MUST be custom fitted  
to a single user’s head. This simple procedure takes  
only a few minutes. Please refer to Fig. 5 and locate  
the parts described.  
1. If the microphone is for yourself, we suggest that  
you use a mirror to double check the fit as you make  
adjustments.  
Fig. 3  
2. Loosen (just a little) the thumbscrew located on  
the outside of the foam block, part way back on the  
boom. This allows the boom to slide in and out, and  
to rotate left and right.  
MIC  
3. Now bend the headband wire to fit your head. Put  
the foam-block wire behind your ear. Then you can  
bend the earpieces to fit snugly around your ears.  
The back of the headband should fit firmly against the  
back of your neck.  
Finish: Satin black.  
Net weight: Head-worn mic, 2.1 oz (61 g). CM-311A  
belt pack and battery, 6.1 oz (173g).  
Dimensions: Headband 5.5-in. (13.97 cm) diameter,  
adjustable. Boom approximately 7 in. (17.78 cm) x  
3 in. (7.62 cm). See Figs. 3 and 4.  
Included accessories: Microphone carrying case,  
WS-6 foam pop filter, clothing clip.  
 

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