Shure MX391 Cardioid Boundary Microphone - Black

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  • Shure MX391 Cardioid Boundary Microphone - Black
  • Shure MX391 Cardioid Boundary Microphone - Black


Equipped with features like programmable, silent membrane switches, logic inputs and outputs, and LED indicators, Microflex Boundary Microphones are the high-quality solution for a range of applications such as altars, boardrooms and distance learning centers. Every Microflex Boundary microphone features a choice of interchangeable condenser cartridges. Their high sensitivity and wide frequency range make them especially suitable for picking up speech and vocals in sound reinforcement and recording applications.


  • Cardioid polar pattern
  • Flat frequency response across the vocal range for uncolored sound
  • Interchangeable cardioid, supercardioid, and omnidirectional cartridges that provide optimal choice for each application
  • Sleek, low-profile design for unobtrusive appearance
  • Balanced, transformerless output for increased immunity to noise over long cable runs
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Frequency Response 50 to 17,000 Hz
Output Impedance (at 1000 Hz) Rated at 150Ω (180Ω actual)
Open Circuit Sensitivity –29.6 dB (33.5 mV)
Maximum Sound Pressure Level 118.8 dB
(1 kHz at 1% Total Harmonic Distortion, 1 kΩ load)
Signal to Noise Ratio (referenced at 94 dB SPL) 71.4 dB
Equivalent Output Noise (A-weighted) 22.6 dB SPL
Dynamic Range at 1 kΩ Load 96.2 dB
Common Mode Rejection 45 dB minimum, 10 Hz to 100 kHz
Preamplifier Output Clipping Level –6 dBV (0.5 V)
Polarity Positive sound pressure on diaphragm produces positive voltage on pin 2 relative to pin 3 of the preamplifier XLR output connector.
Power Requirements 11 to 52 Vdc phantom; 2.0 mA current consumption
Operating Temperature Range –18° C to 57° C (0° F to 135° F)
Relative Humidity 0 to 95%

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