Crown CM-312A Quick Start Manual

CM-312A
CM-312AE
T
he Crown CM-312A is a rugged,
lightweight head-worn microphone
designed for aerobics, live entertain-
ment, and sports broadcasting. It is in-
tended for applications that require a
light, inconspicuous mic.
Because the microphone is to the side of
the mouth, breath pops are eliminated. The
sound of the CM-312A can be tailored to
taste by moving the microphone closer or
farther from the corner of the mouth.
The CM-312A sounds like the best handheld
microphones. Its hypercardioid pickup
pattern reduces feedback and aids isolation.
In difficult situations, the Crown CM-311A
headworn mic is recommended because it
picks up even less feedback and leakage
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 models are available: CM-312A and
CM-312AE. The CM-312A is powered by a
9V battery or phantom power. It has a
battery belt pack with a battery on/off
switch, a programmable mic on/off switch,
and a "Mic On" LED. The CM-312AE has no
connector; you connect it to a wireless
transmitter of your choice.
How to adjust for best fit
For best results, the CM-312A MUST be
custom fitted to one wearer'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.
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 bend the headband wire to fit your
head. Put the foam-block wire behind your
HYPERCARDIOID HEAD-WORN
CONDENSER MICROPHONE
Specifications
Transducer type: Electret condenser.
Frequency response (typical): 50 Hz to
17,000 Hz (see Fig. 1).
Polar pattern: Hypercardioid (see Fig. 2).
Impedance: CM-312A, 75 ohms balanced.
CM-312AE, 6 kilohms unbalanced.
Recommended load impedance: CM-312A,
1000 ohms or greater. CM-312AE, 10
kilohms.
Open-circuit sensitivity, 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 sensitivity, typical, close-talking:
CM-312A: –43 dB re 1 mW/Pa*.
CM-312AE: –65 dB re 1 mW/Pa.
Equivalent noise level (self noise): 31 dB
SPL typical (0 dB = 0.0002 dyne/cm
A-weighted.
S/N ratio: 63 dB at 94 dB SPL.
Maximum SPL: 148 dB SPL produces 3%
THD.
Operating voltage: CM-312A, 9V DC internal
alkaline battery or 18-48V phantom power.
CM-312AE, 3–9V DC from the transmitter's
battery.
Polarity: Positive pressure on diaphragm
produces positive voltage on pin 2 with
respect to pin 3, and on CM-312AE white
lead with respect to shield.
Current drain: CM-312A, 6 mA nominal.
CM-312AE, 0.27 mA nominal.
Battery life: CM-312A, 90 hours. CM-312AE,
approximately equal to transmitter battery
life.
Off-attenuation: 70 dB @ 1kHz.
Output connectors: CM-312A, 3-pin pro audio
(XLR type). CM-312AE, supply your own to
match your transmitter.
Cables (CM-312A): 2-conductor shielded,
unbalanced cable, 3-feet (0.915-m) from
mic capsule to battery pack. Use 2-
conductor shielded mic cable (not included)
between XLR connector and mixer mic
input.
Cable (CM-312AE): 45-inches long (1.144-m),
2-conductor shielded unbalanced cable,
unterminated. In-line with this cable is a
small circuit module that equalizes the
microphone signal.
Materials: High-impact plastic and PVC mic
housing, brass boom, steel wire headband,
high-impact plastic and steel battery pack.
2 ),
Finish: Satin black.
Net weight: Head-worn mic, 1.5 oz (43 g).
CM-312A belt pack and battery, 6.1 oz
(173 g).
Dimensions: Headband 5.5 in. (13.97 cm)
diameter, adjustable. Boom approximately
5.75 in. (14.61 cm). See Figs. 3 and 4.
Included accessories: Microphone carrying
case, WS-7 foam pop filter and clothing clip
for aerobics.
Optional accessories: PH-4B phantom power
supply (4 channels, AC powered). PH-1A
phantom power supply (1 channel, battery
or AC-adapter powered).
*1 pascal = 10 dynes/cm 2 = 10 microbars = 94 dB SPL.