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Crown International, Inc.
1718 W. Mishawaka Rd.
Elkhart, IN 46517-9439
TEL: 574-294-8000
FAX: 574-294-8FAX
www.crownaudio.com
7/08 102546-9A
Fig. 5
Fig. 4
After several hours of use, the foam pop fi lter can be-
come clogged with moisture, giving a muffl ed sound.
Periodically wash it in mild detergent and water. The
foam pop fi lter is held in place by a removable ring.
Additional WS-6 pop fi lters can be ordered from
Crown’s Parts Department.
How to insert a battery in the CM-311A belt pack
1. Access the battery by sliding open the battery cover.
2. Insert a fresh 9V alkaline battery (Mallory Duracell
MN1604 or equivalent) into the battery tray. The bat-
tery cover shows the correct polarity.
3. Replace the battery cover. To prolong battery life,
turn off the battery switch when not in use.
If you’re using phantom power, and the battery switch
is on, the battery will take over automatically if phan-
tom power fails.
After 85 hours of use, or if the sound is distorted, it’s
time to replace the battery.
How to program the mic on/off switch
The mic on/off switch can be programmed to work in
three ways:
* Push-on/push-off.
* Momentary on.
* Momentary off (as supplied).
To change the switch operation, open the belt-pack
case by removing the three screws. Set the switch as
shown below:
How to connect the CM-311AE to a wireless trans-
mitter
1. Solder on a connector that mates with your trans-
mitter. Technical Bulletin #3 (included) shows the
correct wiring for various transmitters. A wireless
transmitter must have separate leads for ground,
audio and bias (3-9 volts).
2. Plug in the cable. Adjust the trim pot on the trans-
mitter input to prevent distortion.
Note: Crown has certain models available for wireless
transmitters from Shure, AKG, Audio-Technica and
Telex. Contact Technical Support for more information
at 800-342-6939.
Architects’ and Engineers’ Specifi cations
The microphone shall be the Crown Model CM-311A
or CM-311AE or equivalent. The microphone shall be
a head-worn, noise-cancelling, cardioid type of elec-
tret-condenser design. The microphone shall exhibit
excellent off-axis response and gain-before-feedback.
The microphone shall have an adjustable headband,
adjustable boom with locking thumbscrew, and foam
pop fi lter.
Model CM-311A shall include a battery belt pack.
Model CM-311AE shall be the head-worn micro-
The LED lights when the mic is on.
Note: For users with petite heads, extra headband
material may have to be cut off to get the headband to
fi t properly.
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.
5. Be sure that the thumbscrew is still loosened a
little. Move the boom in or out, and left or right, to
center the mic directly in front of your lips. The foam
pop fi lter should press fi rmly against the lips. This
is necessary because the mic cancels sounds that are
not close to it. Also, it keeps the boom from bouncing.
Tighten the thumbscrew and you’re done.
Once you’ve adjusted the headset, it should remain
in that position -- no further adjustments are needed.
You can still swing the mic up or down, away from
your lips, if you don’t want to be heard on the P.A.
— or use the mic on/off switch programmed for
“press off” operation.
phone alone. In the CM-311A, a 42-inch, permanently
attached, two-conductor shielded cable shall con-
nect the microphone to the belt pack. The belt pack
shall include a 3-pin pro audio (XLR type) connector.
In the CM-311AE, a 42-inch, permanently attached,
two-conductor shielded cable can be connected to a
transmitter.
Model CM-311A shall be powered by a 9V battery in
the belt pack, or by 18 to 48V phantom power. The
belt pack shall have a battery on/off switch, a pro-
grammable mic on/off switch, and a “Mic On” LED.
Model CM-311AE shall be powered by 3–9V DC from
a transmitter.
Nominal open-circuit sensitivity shall be 4 or 1.25
mV/Pa. Maximum SPL shall be 148 dB SPL for 3%
THD. Equivalent noise shall be 27 dBA nominal.
Frequency response shall be 50 Hz to 17,000 Hz with a
uniform off-axis response, over 20 dB down at the rear
null. The Crown models CM-311A and CM-311AE are
specifi ed.
Microphone Warranty
Crown professional microphones are guaranteed
against malfunction for a period of three years from
date of original purchase. See enclosed warranty sheet
for additional information.
Service
If the microphone does not function properly, check
that it is aimed correctly and is connected as
described in this datasheet. If the microphone is
defective, return it in the original packaging to: Crown
Factory Service, 1718 West Mishawaka Road,
Elkhart, IN 46517-9439.
A Service Return Authorization (SRA) is required
for product being sent to the factory for service. An
SRA can be completed on line at www.crownaudio.
com/support/factserv.htm. For further assistance or
technical support call 800-342-6939.
CM-311A
CM-311AE
© 2008 Crown Audio
®
, Inc. Specifi cations subject to
change without prior notice. Latest information avalable at
www.crownaudio.com. Crown, Crown Audio and Differoid
are registered trademarks of Crown International.