Shure MX391/C

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.

The MX391 includes an attached 4 meter (12 ft) cable terminated with a 4-pin mini connector and separate preamplifier. A rubber strain relief is provided for applications that require removing the 4-pin mini connector and connecting the mic cable directly to screw terminals in the preamplifier.

Environmental Requirements
Operating Temperature Range: -18 to 57 degrees C (0 to 135 degrees F)
Relative Humidity: 0 to 95%

All measurements taken with the microphone mounted on a 76.2 cm x 76.2 cm (30 in. x 30 in.) wooden surface and with the sound source incident at 30 degrees with respect to the surface plane.

Frequency Response
50 to 17,000 Hz

Output Impedance (at 1000 Hz)
180 ohms actual (rated at 150 ohms)

Open Circuit Sensitivity 1 kHz ref. 1 V per Pascal *
Cardioid: -29.6 dB (33.5 mV)
All settings -12 dB at 0 gain; *1 Pascal = 94 dB SPL

Maximum Sound Pressure Level (1 kHz at 1% Total Harmonic Distortion, 1 k ohm load)
Cardioid: 118.8 dB
All settings +6 dB at 0 gain

Signal to Noise Ratio (referenced at 94 dB SPL)
Cardioid: 71.4 dB

Equivalent Output Noise (A-weighted)
Cardioid: 22.6 dB SPL

Dynamic Range at 1 k ohm Load
96.2 dB
100 dB at 0 gain

Common Mode Rejection
45 dB minimum, 10 Hz to 100 kHz

Preamplifier Output Clipping Level
-6 dBV (0.5 V)
12 dB at 0 gain

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