Crown MINI-BOUNDARY MB-2 Datasheet

MB-2
T he Crown ® MB-2 is a miniature boundary
microphone for multi-miking applications
such as teleconferencing, distance learning,
boardrooms, and courtrooms. This tiny mic plugs
into a table-mounted jack.
A low-profi le 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.
Thanks to its supercardioid pickup pattern, the
MB-2 greatly reduces ambient noise and pickup of
room reverberation. The result is a clearer sound.
The MB-2 must be used with an MB-100 interface
(not included). The interface performs these
functions:
• Powers and equalizes up to four mics.
• Provides programmable switching to turn
the mic on or off if desired (switches not
provided).
• Plug-in microphone inputs.
• Provides balanced outputs from the interface.
MB-2 Advanced Features
• Paintable removable grille assembly.
• A common interface for up to four mics re-
duces the size and cost of the system.
• Low-Z balanced output prevents hum and
high-frequency loss.
• On/off switches can be added.
• Switches can be internally programmed for
touch-on/touch off, momentary on, or mo-
mentary off.
• Defeatable LED.
How to Paint the Microphone
1. Using a small screwdriver, pry open one side of
the base, then the other side (Fig. 5).
2. Remove foam liner.
3. Wearing a dust mask, spray-paint the grille as-
sembly. Be sure grille holes are not clogged.
4. Allow paint to completely dry.
5. Make sure the LED is properly aligned.
6. Carefully place the grille assembly over the LED
and snap in place.
POLAR
PATTERN
MINI-BOUNDARY
MICROPHONE
Features
• Ideal for teleconferencing, distance
learning, boardrooms and courtrooms
• Plugs into a table-mounted jack
Specifi cations
All specs apply to each output of the interface with a
mic connected.
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.
Equivalent noise level (self-noise): 22 dB SPL typi-
cal (0 dB=0.0002 dyne/cm
S/N ratio: 72 dB at 94 dB SPL.
Maximum SPL: 120 dB SPL at 3% THD.
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.
Operating voltage: Interface requires 18-48V phan-
tom power.
Current drain: 5 mA nominal with LED on, 4 mA
nominal with LED off.
Mic connector: Stereo phone plug. Mates with
Switchcraft 152B Thick Panel Phone Jack or
equivalent (not supplied). Order from Crown as an
MB-JK.
Cable connectors (supplied with MB-100 interface):
• 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.
• Two PTBs for remote switch sensing. Each PTB
connects to two remote switch sensors.
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.
™
• Half-supercardioid polar pattern reduces
• Clear, natural sound
• Small and inconspicuous
Safe operating temperature range: –10° to +50° C,
Materials: High-impact molded plastic and steel
Finish: Satin black.
Net weight: 0.7 ounce (20.1 grams).
Dimensions: See Fig. 4.
Required accessory: MB-100 interface.
*1 pascal = 10 dynes/cm
Fig. 1
2 ), A-weighted.
Fig. 2
feedback, room acoustics and background
noise
Use twisted-pair cable between each user switch
and interface.
or +14° to +122° F.
mesh mic grille, steel chassis.
2 = 10 microbars = 94 dB SPL.
Frequency Response
Frequency in Hz
Horizontal-Plane Polar Response