Crown Audio specifications Specifications, MB-2 Advanced Features, Mini-Boundary Microphone

POLAR

PATTERN

MB-2

he Crown® MB-2 is a miniature boundary Tmicrophone for multi-miking applications

such as teleconferencing, distance learning, boardrooms, and courtrooms. This tiny mic plugs into a table-mounted jack.

MINI-BOUNDARY™

MICROPHONE

Features	•	Half-supercardioid polar pattern reduces
• Ideal for teleconferencing, distance		feedback, room acoustics and background
		noise
learning, boardrooms and courtrooms
• Plugs into a table-mounted jack	•	Clear, natural sound
	•	Small and inconspicuous

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.

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

Specifications

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.

Use twisted-pair cable between each user switch and interface.

Safe operating temperature range: –10° to +50° C, or +14° to +122° F.

Materials: High-impact molded plastic and steel mesh mic grille, steel chassis.

Finish: Satin black.

Net weight: 0.7 ounce (20.1 grams).

Dimensions: See Fig. 4.

Required accessory: MB-100 interface.

*1 pascal = 10 dynes/cm2 = 10 microbars = 94 dB SPL.

Fig. 1

Frequency Response

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.

Equivalent noise level (self-noise): 22 dB SPL typi- cal (0 dB=0.0002 dyne/cm2), A-weighted.

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.		Frequency in Hz
Current drain: 5 mA nominal with LED on, 4 mA	Fig. 2
nominal with LED off.
Mic connector: Stereo phone plug. Mates with		Horizontal-Plane Polar Response
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.