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POLAR
PATTERN
CM-312AE
HYPERCARDIOID HEADWORN
CONDENSER MICROPHONE
T
he Crown
®
CM-312AE is a rugged, lightweight
headworn microphone designed for aerobics,
live entertainment, and sports broadcasting. It is
intended for wireless-mic applications that require a
light, inconspicuous mic.
The CM-312AE has no connector; you solder on a
connector that mates with a wireless transmitter of
your choice. Technical Bulletin #3 (included) shows
the correct wiring for various transmitters.
Because the microphone is to the side of the mouth,
breath pops are eliminated. The sound of the
CM-312AE can be tailored to taste by moving the
microphone closer or farther from the corner of the
mouth.
The CM-312AE sounds like the best handheld mi-
crophones. Its hypercardioid pickup pattern reduces
feedback and aids isolation. In diffi cult situations, the
Crown CM-311AE headworn mic is recommended
because it picks up even less feedback and leakage
than the CM-312AE.
Designed for comfort, the headband fi ts behind the
head and disappears in use. Both the headband and
boom adjust to fi t any head. Because of the boom’s
unique behind-the-ear design, it does not cover up the
user’s face.
How to adjust for best fi t
For best results, the CM-312AE MUST be custom fi t-
ted to one wearer’s head. This simple procedure takes
only a few minutes. Please refer to Fig. 3 and locate
the parts described.
1. If the microphone is for yourself, we suggest that
you use a mirror to double check the fi t as you make
adjustments.
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.
3. Now adjust the headband to fi t your head. Put the
foam block wire behind your ear.
Start bending the headband wire from the boom
side, moving around to the other ear. The back of the
headband should fi t fi rmly against the back of the
neck. If you can slide a fi nger between the headband
and the back of your neck, then the headband is not
fi tted correctly. For users with smaller or petite heads,
you may have to re-bend the earpiece around the ear,
and cut off extra headband material.
4. Next, adjust the foam pad snug against your head
or neck. To do this, bend the wire that goes into the
foam block. CAUTION! Do not bend the boom itself
– just the foam-block wire. A snug fi t of the foam pad
prevents boom bounce when you move around.
Specifi cations
Transducer type: Electret condenser.
Frequency response (typical): 50 Hz to 17,000 Hz (see
Fig. 1).
Polar pattern: Hypercardioid (see Fig. 2).
Impedance: 6 kilohms unbalanced.
Recommended load impedance: 10 kilohms.
Open-circuit sensitivity, typical, close-talking:
2.9 mV/Pa* (–51 dB re 1V/Pa*).
Power sensitivity, typical, close-talking:
–65 dB re 1 mW/Pa*.
Equivalent noise level (self noise): 31 dB SPL typical
(0 dB = 0.0002 dyne/cm
2
), A-weighted.
S/N ratio: 63 dB at 94 dB SPL.
Maximum SPL: 148 dB SPL produces 3% THD.
Operating voltage: 3–9V DC from the transmitter’s battery.
Polarity: Positive pressure on diaphragm produces posi-
tive voltage on white lead with respect to shield.
Current drain: 0.27 mA nominal.
Battery life: Approximately equal to transmitter battery
life.
Operating temperature range: –18° to +57° C, or 0° to
+135° F.
Off-attenuation: 70 dB @ 1kHz.
Output connectors: Supply your own to match your
transmitter.
Cable: 45-inches long (1.14-m), 2-conductor shielded
unbalanced cable, unterminated. In-line with this cable
is a small circuit module that equalizes the microphone
signal. White lead is audio, red lead is DC bias, and
shield is ground.
Materials: High-impact plastic and PVC mic housing,
brass boom, steel wire headband.
Finish: Satin black.
Net weight: 1.5 oz (43 g).
Dimensions: Headband 5.5 in. (13.97 cm) diameter,
adjustable. Boom approximately 5.75 in. (14.61 cm).
See Fig. 6.
Included accessories: Microphone carrying case, WS-7
foam pop fi lter and clothing clip for aerobics.
*1 pascal = 10 dynes/cm
2
= 10 microbars = 94 dB SPL.
Frequency in Hz
Frequency Response
Fig. 1
Fig. 3 Parts
Fig. 2
20 100
1K
10K
+15
+10
+5
0
-5
-10
-15
-20
-25
-30
-35
0°, 1.375 in.
0°, 2 ft.
120°, 2 ft.
20K
dB
FRONT
REAR
-20
-15
-10
-5
-0
60°
90°
120°
150°180°
210°
240°
270°
300°
0°
30°
330°
1000 Hz
300 Hz
6000 Hz
Polar Response
TO MOVE MIC
UP OR DOWN
TO MOVE MIC
IN OR OUT
TO MOVE MIC
LEFT OR RIGHT
THUMBSCREW
FOAM BLOCK
EARPIECE
MIC
HEADBAND
WIRE
DETAIL
BOOM
FOAM BLOCK
WIRE