Crown DIFFEROID CM-311A User manual

CM-311A
CM-311AE
DIFFEROID HEAD-WORN
CONDENSER MICROPHONE
Designed for touring and live-sound applica-
tions, the Crown®CM-311A is a rugged
head-worn microphone with unequalled
performance. It sounds like the best handheld
microphones—full, clear, and distortion-free, even
with the loudest singers.
The CM-311A is the latest version of the Crown’s
proprietary Differoid®technology. Its cardioid
pickup pattern rejects sounds from the rear, such as
floor monitors. Its noise-canceling ability rejects
sounds at a distance, such as instruments on stage
and crowd noise. This results in the CM-311A
having outstanding gain-before-feedback and
isolation.
Lightweight and comfortable, the mic’s headband
and boom adjust to fit any singer. An included pop
filter greatly reduces breath noise and pops. Be-
cause of the boom’s unique behind-the-ear design,
it does not cover up the singer’s face.
Two models are available: CM-311A and CM-311AE.
The CM-311A is powered by a 9V battery or phan-
tom power. It has a battery belt pack with an on/off
switch, a programmable mic on/off switch, and a
“Mic On” LED. The CM-311AE is a pig-tail version
allowing you to connect it to the wireless transmit-
ter of your choice.
NOTE: Putting an XLR connector on the CM-311AE
and connecting to a mic input with phantom power
WILL damage the mic element. For wired applica-
tions, use the CM-311A.
How to adjust for best fit and to prevent boom
bounce
Note: To get the maximum performance out of this
microphone, take the time to adjust it to fit cor-
rectly.
For best results, the CM-311A MUST be custom
fitted to a single user’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 ear. Then you can
bend the earpieces to fit snugly around your ears.
The back of the headband should fit firmly against
the back of your neck.
CM-311A
CM-311AE
Specifications
Transducer type: Electret condenser.
Frequency response (typical): 50 Hz to 17,000 Hz
(see Fig. 1).
Polar pattern: Cardioid (see Fig. 2).
Impedance: CM-311A, 75 ohms balanced. CM-
311AE, 6 kilohms unbalanced.
Recommended load impedance: CM-311A, 1000
ohms or greater. CM-311AE, 10 kilohms.
Open-circuit sensitivity, typical, close-talking: CM-
311A, 4 mV/Pa* (–48 dB re 1V/Pa), CM-311AE,
1.25 mV/Pa (–58 dB re 1V/Pa).
Power sensitivity, typical, close-talking: CM-
311A: –42.5 dB re 1 mW/Pa*, CM-311AE: –71.5
dB re 1 mW/Pa.
Equivalent noise level (self noise): 26 dB SPL
typical (0 dB = 0.0002 dyne/cm2), A-weighted.
S/N ratio: 68 dB at 94 dB SPL.
Maximum SPL: CM-311A, 148 dB SPL produces 3%
THD. CM-311AE, 140 dB SPL with 3V DC, 148 dB
SPL with 9V DC.
Operating voltage: CM-311A, 9V DC internal
alkaline battery or 18-48V phantom power. CM-
311AE, 3–9V DC from the transmitter’s battery.
Polarity: Positive pressure on diaphragm produces
positive voltage on CM-311A XLR pin 2 with
respect to pin 3, and on CM-311AE shield with
respect to white lead.
Current drain: CM-311A, 6.5 mA nominal.
CM-311AE, 0.27 mA nominal.
Battery life: CM-311A, 85 hours. CM-311AE,
approximately equal to transmitter battery life.
Off-attenuation: 70 dB.
Output connectors: CM-311A, 3-pin pro audio (XLR
type). CM-311AE, supply your own to match your
transmitter.
Cables (CM-311A): 2-conductor shielded,
unbalanced cable, 42-inches (106.68 cm) from
headband to battery pack. Use 2-conductor
shielded mic cable (not included) between XLR
connector and mixer mic input.
Cable (CM-311AE): In-line with this cable is a small
circuit module that equalizes the microphone
signal. Cable is 42-inches (106.68 cm) long from
headband to module, 12-inches (30.48 cm) from
module to cable end. 2-conductor shielded
unbalanced cable, unterminated.
Materials: High-impact plastic mic housing, brass
boom, steel wire headband, high-impact plastic
and steel battery pack.
Finish: Satin black.
Net weight: Head-worn mic, 2.1 oz (61 g). CM-311A
belt pack and battery, 6.1 oz (173g).
Dimensions: Headband 5.5-in. (13.97 cm) diameter,
adjustable. Boom approximately 7 in. (17.78 cm)
x 3 in. (7.62 cm). See Figs. 3 and 4.
Included accessories: Microphone carrying case,
WS-6 foam pop filter, clothing clip.
Optional accessories: PH-4B phantom power
supply (4 channels, AC powered). PH-1A
phantom power supply (1 channel, battery or AC-
adapter powered). WS-14 accessory windscreen.
*1 pascal = 10 dynes/cm2= 10 microbars = 94 dB SPL.
Frequency in Hz
20 100 1K 10K
+15
+10
+5
dB 0
-5
-10
-15
-20
-25
-30
-35
0˚, 1.375"
0˚ 2'
120˚, 2'
20K
Frequency Response
Fig. 2
Fig. 1
MIC
Fig. 3
Polar Response
POLAR
PATTERN

Crown International, Inc.
P. O. Box 1000
Elkhart, IN 46515-1000
TEL: [phone]
FAX: [phone]FAX
www.crownaudio.com
TOURING
TOURING
©2003 Crown Audio, Inc. Specifications subject to
change without prior notice. Latest information
available at www.crownaudio.com. Crown and
Differoid are registered trademarks of Crown Interna-
tional.
9/03 102546-6
Fig. 5
Fig. 4 After several hours of use, the foam pop filter can
become clogged with moisture, giving a muffled
sound. Periodically wash it in mild detergent and
water. The foam pop filter is held in place by a
removable ring.
Additional WS-6 pop filters 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
MN9100 or equivalent) into the battery tray. The
battery 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 phantom 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
transmitter
1. Solder on a connector that mates with your
transmitter. 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
transmitter 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’ Specifications
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 electret-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 filter.
Model CM-311A shall include a battery belt pack.
Model CM-311AE shall be the head-worn micro-
phone alone. In the CM-311A, a 42-inch, perma-
nently attached, two-conductor shielded cable shall
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 fit 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 fit 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 filter should press firmly 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.
connect 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 specified.
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 de-
scribed 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. For further assistance or
technical support call 800-342-6939.
CM-311A
CM-311AE