CM-312A
CM-312AE
HYPERCARDIOID HEAD-WORN
CONDENSER MICROPHONE
The Crown CM-312A is a rugged,
ightweight head-worn microphone
designed for aerobics, ive entertain-
ment, and sports broadcasting. It is in-
tended for app ications that require a
ight, inconspicuous mic.
Because the microphone is to the side of
the mouth, breath pops are e iminated. The
sound of the CM-312A can be tai ored to
taste by moving the microphone c oser or
farther from the corner of the mouth.
The CM-312A sounds ike the best handhe d
microphones. Its hypercardioid pickup
pattern reduces feedback and aids iso ation.
In difficu t situations, the Crown CM-311A
headworn mic is recommended because it
picks up even ess feedback and eakage
than the CM-312A.
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 be-
hind-the-ear design, it does not cover up the
user’s face.
Two mode s are avai ab e: CM-312A and
CM-312AE. The CM-312A is powered by a
9V battery or phantom power. It has a
battery be t pack with a battery on/off
switch, a programmab e mic on/off switch,
and a “Mic On” LED. The CM-312AE has no
connector; you connect it to a wire ess
transmitter of your choice.
How to adjust for best fit
For best resu ts, the CM-312A MUST be
custom fitted to one wearer’s head. This
simp e procedure takes on y a few minutes.
P ease refer to Fig. 5 and ocate the parts
described.
1. If the microphone is for yourse f, we
suggest that you use a mirror to doub e
check the fit as you make adjustments.
2. Loosen (just a itt e) the thumbscrew
ocated on the outside of the foam b ock,
part way back on the boom. This a ows the
boom to s ide in and out, and to rotate eft
and right.
3. Now bend the headband wire to fit your
head. Put the foam-b ock wire behind your
Specifications
Transducer type: E ectret condenser.
Frequency response (typical): 50 Hz to
17,000 Hz (see Fig. 1).
Polar pattern: Hypercardioid (see Fig. 2).
Impedance: CM-312A, 75 ohms ba anced.
CM-312AE, 6 ki ohms unba anced.
Recommended load impedance: CM-312A,
1000 ohms or greater. CM-312AE, 10
ki ohms.
Open-circuit sensiti ity, typical, close-
talking: CM-312A, 3.8 mV/Pa* (–48.5 dB re
1V/Pa), CM-312AE, 2.9 mV/Pa (–51 dB re
1V/Pa).
Power sensiti ity, typical, close-talking:
CM-312A: –43 dB re 1 mW/Pa*.
CM-312AE: –65 dB re 1 mW/Pa.
Equi alent noise le el (self noise): 31 dB
SPL typica (0 dB = 0.0002 dyne/cm2),
A-weighted.
S/N ratio: 63 dB at 94 dB SPL.
Maximum SPL: 148 dB SPL produces 3%
THD.
Operating oltage: CM-312A, 9V DC interna
a ka ine battery or 18-48V phantom power.
CM-312AE, 3–9V DC from the transmitter’s
battery.
Polarity: Positive pressure on diaphragm
produces positive vo tage on pin 2 with
respect to pin 3, and on CM-312AE white
ead with respect to shie d.
Current drain: CM-312A, 6 mA nomina .
CM-312AE, 0.27 mA nomina .
Battery life: CM-312A, 90 hours. CM-312AE,
approximate y equa to transmitter battery
ife.
Off-attenuation: 70 dB @ 1kHz.
Output connectors: CM-312A, 3-pin pro audio
(XLR type). CM-312AE, supp y your own to
match your transmitter.
Cables (CM-312A): 2-conductor shie ded,
unba anced cab e, 3-feet (0.915-m) from
mic capsu e to battery pack. Use 2-
conductor shie ded mic cab e (not inc uded)
between XLR connector and mixer mic
input.
Cable (CM-312AE): 45-inches ong (1.144-m),
2-conductor shie ded unba anced cab e,
unterminated. In- ine with this cab e is a
sma circuit modu e that equa izes the
microphone signa .
Materials: High-impact p astic and PVC mic
housing, brass boom, stee wire headband,
high-impact p astic and stee battery pack.
Finish: Satin b ack.
Net weight: Head-worn mic, 1.5 oz (43 g).
CM-312A be t pack and battery, 6.1 oz
(173 g).
Dimensions: Headband 5.5 in. (13.97 cm)
diameter, adjustab e. Boom approximate y
5.75 in. (14.61 cm). See Figs. 3 and 4.
Included accessories: Microphone carrying
case, WS-7 foam pop fi ter and c othing c ip
for aerobics.
Optional accessories: PH-4B phantom power
supp y (4 channe s, AC powered). PH-1A
phantom power supp y (1 channe , battery
or AC-adapter powered).
*1 pasca = 10 dynes/cm2 = 10 microbars = 94 dB SPL.
