POLAR
PATTERN
™
MINI-BOUNDARY
MICROPHONE
MB-2
•
Half-supercardioid polar pattern reduces
feedback, room acoustics and background
noise
Features
•
Ideal for teleconferencing, distance
learning, boardrooms and courtrooms
•
•
Clear, natural sound
he Crown® MB-2 is a miniature boundary
microphone for multi-miking applications
such as teleconferencing, distance learning,
•
Plugs into a table-mounted jack
Small and inconspicuous
T
boardrooms, and courtrooms. This tiny mic plugs
into a table-mounted jack.
A low-profile rectangular microphone, the MB-2
has a bottom-mounted phone plug. It plugs into a
stereo phone jack previously installed in the table.
The contractor supplies the phone jack, which is
a Switchcraft 152B Thick Panel Phone Jack or
equivalent. A locating pin (removable) prevents the
microphone from being rotated.
Use twisted-pair cable between each user switch
and interface.
Specifications
All specs apply to each output of the interface with a
mic connected.
Safe operating temperature range: –10° to +50° C,
or +14° to +122° F.
Type: Phase Coherent Cardioid.
Element: Electret condenser.
Materials: High-impact molded plastic and steel
mesh mic grille, steel chassis.
Frequency response (typical): 50 Hz to 15,000 Hz at
30 degrees incidence to surface (see Fig. 1).
Finish: Satin black.
Thanks to its supercardioid pickup pattern, the
MB-2 greatly reduces ambient noise and pickup of
room reverberation. The result is a clearer sound.
Net weight: 0.7 ounce (20.1 grams).
Dimensions: See Fig. 4.
Polar pattern: Half-supercardioid (supercardioid in
the hemisphere above the primary boundary). See
Figs. 2 and 3.
Required accessory: MB-100 interface.
The MB-2 must be used with an MB-100 interface
(not included). The interface performs these
functions:
Impedance: 150 ohms, balanced. Recommended
load impedance 1000 ohms or greater.
*1 pascal = 10 dynes/cm2 = 10 microbars = 94 dB SPL.
Open-circuit sensitivity (typical): 22 mV/Pa* (–33
dB re 1 volt/Pa).
• Powers and equalizes up to four mics.
Power sensitivity: –30.5 dB re 1 mW/Pa*. EIA rating
–125 dBm.
• Provides programmable switching to turn
the mic on or off if desired (switches not
provided).
Fig. 1
Frequency Response
Equivalent noise level (self-noise): 22 dB SPL typi-
cal (0 dB=0.0002 dyne/cm2), A-weighted.
• Plug-in microphone inputs.
S/N ratio: 72 dB at 94 dB SPL.
• Provides balanced outputs from the interface.
Maximum SPL: 120 dB SPL at 3% THD.
MB-2 Advanced Features
• Paintable removable grille assembly.
Polarity: Positive (inward) pressure on the diaphragm
produces positive voltage on interface output ter-
minal 1 with respect to terminal 3, and on terminal
4 with respect to terminal 6.
• A common interface for up to four mics re-
duces the size and cost of the system.
Operating voltage: Interface requires 18-48V phan-
tom power.
• Low-Z balanced output prevents hum and
high-frequency loss.
Frequency in Hz
Current drain: 5 mA nominal with LED on, 4 mA
nominal with LED off.
Fig. 2
• On/off switches can be added.
Horizontal-Plane Polar Response
Mic connector: Stereo phone plug. Mates with
Switchcraft 152B Thick Panel Phone Jack or
equivalent (not supplied). Order from Crown as an
MB-JK.
• Switches can be internally programmed for
touch-on/touch off, momentary on, or mo-
mentary off.
• Defeatable LED.
Cable connectors (supplied with MB-100 interface):
How to Paint the Microphone
1. Using a small screwdriver, pry open one side of
the base, then the other side (Fig. 5).
• Two pluggable terminal blocks (PTBs) in line with
the microphones. Each input connector handles
up to two mics.
• Two PTBs for output connectors to your mixer.
Each output connector feeds two mixer mic
inputs.
2. Remove foam liner.
3. Wearing a dust mask, spray-paint the grille as-
sembly. Be sure grille holes are not clogged.
• Two PTBs for remote switch sensing. Each PTB
connects to two remote switch sensors.
4. Allow paint to completely dry.
Cable: None supplied. Use two-conductor shielded
mic cable between phone jack and pluggable
terminal block. Use two-conductor shielded mic
cable between interface output and mixer input.
5. Make sure the LED is properly aligned.
6. Carefully place the grille assembly over the LED
and snap in place.
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