AKG MB3 Manuals

T MB3 MINI-BOUNDARY ™ MICROPHONE he AKG/Crown® MB3 is a miniature boundary microphone for multi-miking applications such as teleconferencing, distance learning, boardrooms, courtrooms, and security applications. This low-profile, circular mic permanently installs into a hole drilled in a table, lectern, or ceiling. 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. On the bottom of the mic is a tubular power module with a 3-pin XLR-type output connec- tor. It is powered by 12-48V phantom power, and has a low-impedance balanced mic-level output. Features • Small, inconspicuous. • Installs permanently in table top, wall or ceiling. • Clean, clear, natural sound. • Low-Z balanced mic-level output prevents hum and high-frequency loss. 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). Fig. 1 +15 +10 +5 dB 0 –5 –10 –15 –20 –25 –30 Frequency Response 0˚ 130˚ • Removable grille assembly can be painted. How to Paint the Microphone 1. Using a small screwdriver, pry open one side of the base, then the other side (Fig. 5). 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 –35 20 100 1K 10K Frequency in Hz Fig. 2 Horizontal-Plane Polar Response 2. Remove the foam liner. 3. Wearing a dust mask, spray-paint the grille assembly. Be sure grille holes are not clogged. 4. Allow to completely dry. 5. Make sure the LED is properly aligned. 6. Carefully place the grille assembly over the base, and snap in place. Installation 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 between every two people. Lecterns: If the microphone will be used on a typical (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 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. Materials: High-impact molded plastic and steel mesh mic grille, steel chassis. 300˚ 270˚ 240˚ 330˚ 0˚ 30˚ FRONT –0 –5 –10 –15 –20 REAR 1 kHz 200 Hz 5 kHz 60˚ 90˚ 120˚ lectern, install it on an open surface. Do not install in a cavity or recessed area as the fre- quency response and polar pattern will be degraded. Finish: Satin black. Net weight: 2.7 ounces (78 grams). Dimensions: See Fig. 4. Fig. 3 210˚ 180˚ 150˚ 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. Note: The system gain-before-feedback may not be adequate in ceiling mount applications because the mic is far from its user. Optional accessories: PH1A phantom power supply (1 channel, battery or DC-adapter powered). PH4A phantom power supply (4 channels, AC powered). *1 pascal = 10 dynes/cm2 = 10 microbars = 94 dB SPL. 30˚ 0˚ Vertical-Plane Polar Response 60˚ 90˚ 120˚ 1 kHz 200 Hz 5 kHz FRONT REAR +5 –0 –5 –10 –15 –20 150˚ 180˚