Frequency Response
(switch set to “announcing”)
CM-310ASW
DIFFEROID
®
MICROPHONE
WITH ON/OFF SWITCH
T
he Crown CM-310ASW Differoid
®
is a
hand-held noise-canceling microphone
for sporting events or other applica-
tions with high ambient sound level. It
features a magnetic reed switch that turns
the mic on and off. The smooth-operating
switch operates silently.
The CM-310ASW uses Crown’s patented
Differoid technology. It is differential or
noise cancelling, so it rejects sounds that
are not close to the microphone. It has a
cardioid polar pattern, so it rejects sounds
from the rear.
These features give the CM-310ASW excep-
tional gain before feedback. It permits ex-
tremely loud P.A. levels before feedback
occurs. The mic also rejects unwanted
background noise. The announcer can sit in
the stands with the audience, with the P.A.
loudspeakers playing loudly, and not experi-
ence feedback.
Inside the mic handle, on the PC board is a
DIP switch that sets the frequency response.
It has two settings: music and announcing.
The music setting sounds warm and
smooth, while the announcing setting has
less bass and more highs for extra intelligi-
bility.
The frequency response is tailored for clear,
natural reproduction of the voice. A built-in
pop filter suppresses explosive breath
sounds. Handling noise is very low. The unit
can withstand repeated drops and abuse, as
well as extremely loud sounds without
distortion.
The output of the CM-310ASW is balanced,
low impedance, which allows long cable
runs without hum pickup or high-frequency
loss. The unit can be phantom powered from
a mixer or other remote power supply.
Included with the CM-310ASW is a conve-
nient carrying pouch, the ASA-2 mic stand
adapter, and a foam windscreen for outdoor
use.
Operating Instructions
Using a 2-conductor shielded microphone
cable, plug the microphone into a mixer mic
input with 12 to 48 volts phantom powering
or use a remote phantom power supply.
Crown makes an AC-powered model PH-4B
supply for powering up to four micro-
phones. Also available is a single-channel
Specifications
Transducer type: Electret condenser.
Frequency response (typical): 80 Hz to 15 kHz. See
Figs.1 and 2.
Polar pattern: Cardioid. See Fig. 3.
Impedance: 200 ohms balanced. Recommended
minimum load impedance 1000 ohms.
Open circuit sensitivity, typical, close talking:
1.7 mv/Pa* (–55.5 dBV/Pa).
Power sensitivity, typical, close talking: –54.5
re 1 mW/Pa*.
Equivalent noise level (self-noise): 21.5 dB SPL
typical (0 dB = .0002 dyne/cm
2
), A-weighted.
S/N ratio: 72.5 dB at 94 dB SPL.
Maximum SPL for 3% THD: 151 dB SPL with 48 V
phantom, 143 dB SPL with 12 V phantom.
Operating voltage: Phantom power, 12 to 48 volts
DC, positive voltage on pins 2 and 3 with respect to
pin 3 of output connector.
Polarity: Positive pressure on the diaphragm
produces a positive voltage on pin 2 with respect
to pin 3 of output connector.
Current drain: 1.5 milliamperes.
Cable: None supplied. Use 2-conductor shielded mic
cable.
Connector: 3-pin professional audio connector (XLR
type).
Switch: Magnetic reed on/off.
Materials: Rugged aluminum alloy housing, steel
grille.
Finish: Satin black.
Net weight: 7.1 oz. (200 g).
Dimensions: See Fig.4.
Included accessories: Carrying pouch, ASA-2 mic
stand adapter and WS-4 windscreen.
Optional accessories: Crown PH-1A phantom power
supply (1 channel, battery or AC adapter powered),
Crown PH-4B phantom power supply (4 channels,
AC powered).
Replacement parts: Field-replaceable CM-310ASW
grille screen is available from Crown’s Parts
Department.
*1 pascal = 10 dynes/cm
2
= 10 microbars = 94 dB
SPL.
Fig. 1
Frequency in Hz
Fig. 2
Polar Response
Fig. 3
FRONT
REAR
60˚
90˚
120˚
150˚
180˚
210˚
240˚
270˚
300˚
0˚
30˚
330˚
500-3500 Hz
250 Hz
10 kHz
–20
–15
–10
–5
–0
20
100
1K
10K
+15
+10
+5
dB 0
–5
–10
–15
–20
–25
–30
–35
0˚ 2 feet
20K
0˚ ¼ inch
1K
10K
20
100
+15
+10
+5
–5
–10
–15
–20
–25
–30
–35
dB 0
0˚, 0 Inches
0˚, 2 Feet
160˚, 2 Feet
20K
Frequency in Hz
Frequency Response
(switch set to “music”)
