D
CM311 A
CM311 AESH
CM311 L
esigned for touring and live-sound
applications, the AKG/Crown CM311
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 CM311 is the latest version of the
AKG/Crown’s
proprietary
Differoid®
technology. Its cardioid pickup pattern
rejects sounds from the rear, such as floor
monitors. Its noise-cancelling ability rejects
sounds at a distance, such as instruments
on stage and crowd noise. This results in
the CM311 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. Because of the
boom’s unique behind-the-ear design, it
does not cover up the singer’s face.
Three models are available: CM311 A, CM311
AESH and CM311 L. The CM311 A is
powered by a 9 V battery or phantom power.
It has a battery belt pack with an on/off
switch, a programmable mic on/off switch,
and a “Mic On” LED. The CM311 AESH has
a T4AF connector, allowing you to connect with
Shure® wireless systems. The L version offers a
3-pin mini XLR output, which fits all AKG wireless
body-pack transmitters.
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 correctly.
For best results, the CM311 A 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.
DIFFEROID
®
HEAD-WORN
CONDENSER MICROPHONE
Specifications
Transducer type: Electret condenser.
Frequency response (typical): 50 Hz to 17,000 Hz
(see Fig. 1).
Polar pattern: Cardioid (see Fig. 2).
Impedance: CM311 A, 75 ohms balanced. CM311
AESH and CM311 L, 6 kilohms unbalanced.
Recommended load impedance: CM311 A,
1000 ohms or greater. CM311 AESH and
CM311 L, 10 kilohms.
Open-circuit sensitivity, typical, close-talking:
CM311 A, 4 mV/Pa* (–48 dB re 1V/Pa),
CM311 AESH and CM311 L, 1.25 mV/Pa
(–58 dB re 1V/Pa).
Power sensitivity, typical, close-talking:
CM311 A: – 42.5 dB re 1 mW/Pa*, CM311
AESH and CM311 L: –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: CM311 A, 148 dB SPL produces
3% THD. CM311 AESH and CM311 L, 140 dB
SPL with 3V DC, 148 dB SPL with 9V DC.
Operating voltage: CM311 A, 9 V DC internal
alkaline battery or 18-48 V phantom power.
CM311 AESH and CM311 L, 3-9 V DC from
the transmitter’s battery.
Polarity: Positive pressure on diaphragm
produces positive voltage on CM311 A XLR
pin 2 with respect to pin 3, and on CM 311
AESH and CM311 L shield with respect to
white lead.
Current drain: CM311 A, 6.5 mA nominal.
CM311 AESH and CM311 L, 0.27 mA
nominal.
Battery life: CM311 A, 85 hours. CM311 AESH
and CM311 L, approximately equal to
transmitter battery life.
Off-
Outpu
(XL
wireless systems
Materials
bras
impac
Finish
Net
CM311
Dimensions
diamete
7
See
Include
case
Optiona
suppl
phanto
AC
windscreen.
*1 pasca
-attenuation: 70 dB.
Output connectors: CM311 A, 3-pin pro audio
(XLR type). CM311 AESH, TA4F for Shure®
wireless systems. CM311 L, 3-pin mini XLR.
Materials: High-impact plastic mic housing,
brass boom, steel wire headband, high-
impact plastic and steel battery pack.
Finish: Satin black.
weight: Head-worn mic, 2.1 oz (61 g).
CM311 A belt pack and battery, 6.1 oz (173g).
Dimensions: Headband 5.5-inch (13.97 cm)
diameter, adjustable. Boom approximately
7-inch (17.78 cm) x 3-inch (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.
pascal = 10 dynes/cm
2
= 10 microbars = 94 dB SPL.