Crown Audio Microphone MB 3 User Manual

POLAR  
PATTERN  
MINI-BOUNDARY™  
MICROPHONE  
MB-3  
he Crown® MB-3 is a miniature boundary  
microphone for multi-miking applications  
such as teleconferencing, distance learn-  
T
ing, boardrooms, courtrooms, and security  
applications. This low-profile, circular mic per-  
manently installs into a hole drilled in a table,  
lectern, or ceiling.  
Features  
Ideal for teleconferencing, distance learning,  
boardrooms, courtrooms and security  
Half-supercardioid polar pattern reduces  
pickup of background noise, room acoustics  
and feedback  
Thanks to its supercardioid pickup pattern, the  
MB-3 greatly reduces ambient noise and pickup  
of room reverberation. The result is a clearer,  
more intelligible sound.  
Small and inconspicuous  
On-surface mounting eliminates phase  
interference from table sound reflections,  
giving a natural sound  
On the bottom of the mic is a tubular power  
module with a 3-pin XLR-type output connector.  
It is powered by 12-48V phantom power, and  
has a low-impedance balanced mic-level output.  
Installs permanently in a table top, wall or  
ceiling  
Specifications  
Type: Phase Coherent Cardioid.  
Element: Electret condenser.  
Frequency response (typical): 50 Hz to 15,000 Hz at  
30 degrees incidence to surface (see Fig. 1).  
Polar pattern: Half-supercardioid (supercardioid in  
the hemisphere above the primary boundary). See  
Figs. 2 and 3.  
Impedance: 150 ohms, balanced (recommended load  
impedance 1000 ohms or greater).  
Open-circuit sensitivity (typical): 22 mV/Pa* (–33  
dB re 1 volt/Pa).  
Power sensitivity: –30.5 dB re 1 mW/Pa*. EIA rating  
–125 dBm.  
How to Paint the Microphone  
Fig. 1  
Frequency Response  
1. See Fig. 5. Using a small screwdriver, pry  
open the FRONT side of the mic cover (grille  
assembly).  
+15  
+10  
+5  
dB 0  
–5  
0˚  
2. Remove the foam liner.  
–10  
–15  
–20  
–25  
–30  
–35  
3. Wearing a dust mask, spray-paint the grille  
assembly. Be sure grille holes are not clogged.  
130˚  
4. Allow to completely dry.  
5. Make sure the LED is properly aligned.  
10K  
20  
100  
1K  
6. Carefully place the grille assembly over the  
base, and snap in place.  
Frequency in Hz  
Fig. 2  
Installation  
Horizontal-Plane Polar Response  
Equivalent noise level (self-noise): 22 dB SPL typi-  
Tables: In a table, typical placement for each  
mic is an arm’s length from the user. Install one  
microphone in front of each person, or one be-  
tween every two people.  
cal (0 dB=0.0002 dyne/cm2), A-weighted.  
0˚  
330˚  
30˚  
FRONT  
S/N ratio: 72 dB at 94 dB SPL.  
Maximum SPL: 120 dB SPL at 3% THD.  
–0  
300˚  
270˚  
240˚  
Polarity: Positive (inward) pressure on the diaphragm  
produces positive voltage on pin 2 with respect  
to pin 3.  
Operating voltage: Phantom power, 12-48 volts DC  
on pins 2 and 3 with respect to pin 1 of output  
connector.  
Current drain: 4 mA nominal.  
Connector: 3-pin pro audio, XLR-M type.  
Cable: None supplied. Use two-conductor shielded  
mic cable.  
60˚  
90˚  
Lecterns: If the microphone will be used on  
a lectern, install it on an open surface. Do  
not install in a cavity or recessed area as the  
frequency response and polar pattern will be  
degraded.  
–5  
–10  
–15  
–20  
Ceilings: When mounting mics in the ceiling,  
use as few mics as possible, and put them  
in front of the people speaking—not directly  
overhead.  
120˚  
1 kHz  
Note: The system gain-before-feedback may  
not be adequate in ceiling mount applications  
because the mic is far from its user.  
Materials: High-impact molded plastic and steel mesh  
200 Hz  
5 kHz  
mic grille, steel chassis.  
REAR  
180˚  
210˚  
150˚  
Finish: Satin black.  
Net weight: 2.7 ounces (78 grams).  
Dimensions: See Fig. 4.  
1. Drill a 1.125-in. (2.858-cm) diameter hole for  
each mic.  
Fig. 3  
Vertical-Plane Polar Response  
Optional accessories: PH-1A phantom power supply  
2. Insert the mic tube through the hole. Orient  
the mic so the word “Crown” is readable by the  
user.  
60˚  
90˚  
120˚  
(1 channel, battery or DC-adapter powered).  
Operating temperature range: –10° to 50° C, or 14°  
to 122° F.  
1 kHz  
200 Hz  
5 kHz  
3. Compression of the gasket under the mic is  
essential to prevent rotation of the mic. Under  
the table, or behind the ceiling or wall panel,  
slide the ring over the tube and tighten the set  
screw.  
150˚  
180˚  
30˚  
*1 pascal = 10 dynes/cm2 = 10 microbars = 94 dB SPL.  
FRONT  
REAR  
0˚  
+
5
–0 –5 –10 15 20  
 

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