POLAR
PATTERN
HYPERCARDIOID HEADWORN
CONDENSER MICROPHONE
CM-312AE
Fig. 1
Frequency Response
+15
+10
+5
0°, 1.375 in.
he Crown® CM-312AE is a rugged, lightweight
headworn microphone designed for aerobics,
live entertainment, and sports broadcasting. It is
0
dB
-5
-10
-15
-20
-25
-30
-35
T
0°, 2 ft.
120°, 2 ft.
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.
20
100
1K
Frequency in Hz
10K 20K
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.
Fig. 2
Polar Response
Specifications
Transducer type: Electret condenser.
330°
0°
30°
FRONT
Frequency response (typical): 50 Hz to 17,000 Hz (see
Fig. 1).
The CM-312AE sounds like the best handheld mi-
crophones. Its hypercardioid pickup pattern reduces
feedback and aids isolation. In difficult situations, the
Crown CM-311AE headworn mic is recommended
because it picks up even less feedback and leakage
than the CM-312AE.
-0
-5
300°
270°
60°
90°
Polar pattern: Hypercardioid (see Fig. 2).
Impedance: 6 kilohms unbalanced.
-10
-15
-20
Recommended load impedance: 10 kilohms.
Open-circuit sensitivity, typical, close-talking:
2.9 mV/Pa* (–51 dB re 1V/Pa*).
Designed for comfort, the headband fits behind the
head and disappears in use. Both the headband and
boom adjust to fit any head. Because of the boom’s
unique behind-the-ear design, it does not cover up the
user’s face.
Power sensitivity, typical, close-talking:
–65 dB re 1 mW/Pa*.
Equivalent noise level (self noise): 31 dB SPL typical
120°
240°
1000 Hz
300 Hz
6000 Hz
(0 dB = 0.0002 dyne/cm2), A-weighted.
S/N ratio: 63 dB at 94 dB SPL.
REAR
180°
How to adjust for best fit
Maximum SPL: 148 dB SPL produces 3% THD.
Operating voltage: 3–9V DC from the transmitter’s battery.
210°
150°
For best results, the CM-312AE MUST be custom fit-
ted to one wearer’s head. This simple procedure takes
only a few minutes. Please refer to Fig. 3 and locate
the parts described.
Polarity: Positive pressure on diaphragm produces posi-
tive voltage on white lead with respect to shield.
Current drain: 0.27 mA nominal.
Fig. 3 Parts
1. If the microphone is for yourself, we suggest that
you use a mirror to double check the fit as you make
adjustments.
Battery life: Approximately equal to transmitter battery
life.
EARPIECE
Operating temperature range: –18° to +57° C, or 0° to
+135° F.
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.
HEADBAND
WIRE
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.
FOAM BLOCK
WIRE
3. Now adjust the headband to fit your head. Put the
foam block wire behind your ear.
MIC
BOOM
FOAM BLOCK
Start bending the headband wire from the boom
side, moving around to the other ear. The back of the
headband should fit firmly against the back of the
neck. If you can slide a finger between the headband
and the back of your neck, then the headband is not
fitted 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.
Materials: High-impact plastic and PVC mic housing,
brass boom, steel wire headband.
THUMBSCREW
DETAIL
Finish: Satin black.
Net weight: 1.5 oz (43 g).
TO MOVE MIC
Dimensions: Headband 5.5 in. (13.97 cm) diameter,
adjustable. Boom approximately 5.75 in. (14.61 cm).
See Fig. 6.
UP OR DOWN
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 fit of the foam pad
prevents boom bounce when you move around.
Included accessories: Microphone carrying case, WS-7
foam pop filter and clothing clip for aerobics.
TO MOVE MIC
IN OR OUT
*1 pascal = 10 dynes/cm2 = 10 microbars = 94 dB SPL.
TO MOVE MIC
LEFT OR RIGHT
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