Crown Audio CM-311AHS Merkblatt

esigned for broadcasters, the Crown

®

 

    CM-311AHS  is  a  rugged  head-worn 
    microphone that mounts on a Sony MDR-

7506 or MDR-V6 headphone. The mic rejects 
background noise extremely well and is ideal for 
use in sporting events. For background noise 
that is extremely high, as in traffi c-copters and 
car races, you may need the extra isolation of a 
David Clark headset. Crown makes an adapter for 
the boom on the David Clark headset. You can 
special-order the adapter from Crown.

The CM-311AHS is the latest version of Crown’s 
patented Differoid

®

 technology. Its cardioid 

pickup pattern rejects noise from behind the 
microphone and its noise-canceling ability rejects 
ambient noise at a distance.

Lightweight and comfortable, the microphone 
adjusts to fi t any user. It mounts securely on 
either earpiece of the popular Sony MDR-7506 
or MDR-V6 headphone. Two included foam pop 
fi lters reduce breath noise, and the windscreen 
reduces wind noise.

Supplied with the microphone is a belt pack. It 
includes a male 3-pin XLR-type output connec-
tor, a battery on/off switch, a programmable 
mic on/off switch, and a “Mic On” LED. The belt 
clip has been designed extra strong to prevent 
breakage and to keep it securely on your belt. 
The microphone is an electret condenser type, 
powered by phantom power or by the 9V battery 
in the belt pack.

Please see Fig. 1. As supplied from the factory, 
the microphone is ready to mount on the right 
earpiece of the Sony headphone. To do this, slip 
the mount over the yoke above the right earpiece 
and tighten the screws. You may want to route 
the mic cable along the headband and along the 
headphone’s coiled cable.

If you want to mount the microphone on the left 
earpiece, please refer to Fig. 6 and follow this 
procedure:

1. Remove thumbscrew that holds boom in block.

2. Pull block off pin.

3. Slide block outer half off to the right.

4. Reverse boom direction; place boom in block 
inner half.

5. Slide block outer half on from the right.  

6. Insert pin into block.

7. Insert thumbscrew and tighten it.

8. Attach mount to left earpiece yoke.

Transducer type: Electret condenser.

Frequency response (typical): 

50 Hz to 15 kHz (see Fig. 2).

Polar pattern: Cardioid (see Fig.3).

Impedance: 75 ohms balanced. 

Open-circuit sensitivity, typical, close-talking: 

4 mV/Pa* (–48 dB re 1 V/Pa*).

Power sensitivity, typical, close-talking:      

 –42.5 dB re 1 mW/Pa.

Equivalent noise level (self-noise):  26 dB SPL typi-

cal (0 dB=.0002 dyne/cm

2

),  A-weighted.

S/N ratio: 68 dB at 94 dB SPL.

Maximum SPL: 148 dB SPL produces 3% THD.

Operating voltage: 9V DC internal alkaline battery (not 

supplied) or 18-48V phantom power.

Polarity: Positive pressure on diaphragm produces 

positive voltage on pin 2 with respect to pin 3 of 
output connector.

Current drain:  5 mA.

Battery life:  110 hours.

Output connector:  3-pin pro audio (XLR type).

Cables:  2-conductor shielded, unbalanced cable, 

4-feet (1.219-m) from mic capsule to battery pack. 
Use 2-conductor shielded mic cable (not included) 
between XLR-type connector and mixer mic input.

Materials:  High-impact plastic mic housing and 

headphone mount, steel mesh grille screen, brass 
boom, steel wire headband, high-impact plastic and 
steel battery pack.

Finish:  Satin black.

Net weight:  Headworn mic and mount, 2.3 oz. 

(64 g). Belt pack and battery, 6.1 oz. (173 g).

Dimensions: See Figs. 4 and 5.

Included accessories: Microphone carrying case, 

WS-6 foam pop fi lter, WS-13 two-stage pop fi lter 
and WS-14 windscreen.

Optional accessories:  PH-1A phantom power supply 

(1 channel, battery or AC/DC adapter powered).

Replacement parts:  WS-6 foam pop fi lter, WS-13 

two-stage pop fi lter, and WS-14 windscreen.

*1 pascal = 10 dynes/cm

2

 = 10 microbars = 94 dB SPL.

The CM-311AHS can be adjusted to fi t any user. 
Please refer to Fig. 1 and follow these steps:

1. Loosen the thumbscrew so the boom moves 
freely.

2. Put on the Sony headphones with the micro-
phone attached.

3. You can move the microphone toward and 
away from your mouth, and also left, right, up and 
down. Position the mic in front of your mouth, 
with lips touching the foam windscreen (Fig. 1). 
This is necessary because the mic cancels sounds 
that are not close to it. To prevent boom bounce, 
the foam pop fi lter should press fi rmly against  the 
lips.

1. Access the battery by sliding open the battery 
cover. 

2. Insert a fresh 9V alkaline battery (Mallory Dura-
cell MN9100 or equivalent) into the  battery clip. 
The battery cover shows the correct polarity.

3. Replace the battery cover.

Connect the belt pack to the mixer using a 2-con-
ductor shielded mic cable with XLR-type connec-
tors. If your mixer lacks phantom power, either 
turn on the battery switch on the  belt pack, or use 
a separate phantom-power supply (such as the 
Crown PH-1A).

If you’re using phantom power and the battery 
switch is on, the battery will automatically take 
over if phantom power fails. Turn off the battery 
switch when not in use to prolong battery life.

After 110 hours of use, or if the sound is distorted, 
it’s time to replace the battery.

The Sony headphones might invert the polarity of 
your voice signal, making it sound weak or colored 
through the headphones. If this happens, you 
might want to invert the polarity of your mixer mic 
channel.

After several hours of use, the foam pop fi lter can 
become clogged with moisture, giving a muffl ed 
sound. You might want to remove the pop fi lter 
periodically and let it dry. It can be washed in mild 
detergent and water. Additional WS-6 and WS-13 
fi lters for yourself or different users can be ordered 
from Crown’s Parts Department.

MOUNT

BOOM

MIC

YOKE

BLOCK

THUMBSCREW