Low profile, professional boundary microphone with interchangeable cartridges. In-line preamp.

Available Options

MX391/C Cardioid, Black
MX391/S Supercardioid, Black
MX391/O Omnidirectional, Black
MX391W/C Cardioid, Off-White
MX391W/S Supercardioid, Off-White
MX391W/O Omnidirectional, Off-White

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.

MX391: Includes 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.




Microphone Type


Lightweight, sensitive diaphragm. Precisely and smoothly captures sound nuances. Powered by battery or phantom power supply.

Polar Pattern


Picks up the most sound in front of the microphone and some from the sides. Less susceptible to feedback in high volume environments.


Equally sensitive to sound from all directions, but cannot be "aimed" to isolate one area.


Screens unwanted sound sources. Ideal for individual instruments in a multi-microphone setting, or single sources in noisy environments.

Frequency Response


Smooth, extended response. Tuned to accentuate specific types of instruments or voices.

Form Factor


Model Line


Microflex Microphones Product Brochure (PDF)
MX391 CAD Drawing (ZIP)
MX391 Specification Sheet (PDF)
MX391 User Guide (PDF)
Related Links
FAQ's for MX391, MX392, MX393
CommShield® Technology White Paper
RF and GSM Resistance
  • 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
  • Programmable on/off switch and LED on/off indicator (MX392/MX393 models only)
  • LED logic input and switch logic output terminals for remote control or use with automatic mixers (MX392 models only)


Polar Pattern
Cardioid (MX391/C, MX391W/C) Supercardioid (MX391/S, MX391W/S) Omnidirectional (MX391/O, MX391W/O)
Frequency Response
50 to 17,000 Hz (Preamp Only)
180 ohms actual (rated at 150 ohms) (Preamp Only)
Output Level
-6 dBV (0.5 V), 12 dB at 0 gain (Preamp Only)
Phantom power required?
11 to 52 Vdc phantom, 2.0 mA current consumption (Preamp Only)

    C129 Cable for Microflex MX393 Microphone

    Cable with CommShield® Technology, 3-Pin female mini-connector to male XLR, 12-foot (3.6 m), used with MX393 Microflex microphones.

    from $32.00

    R183 R183B and R183W Omnidirectional Cartridge

    Omnidirectional cartridge for all Microflex® MX183, MX202, MX391, MX392, MX393, MX405, MX410, MX415, MX412, MX418, and WL183 microphones. White or Black.

    from $39.00

    R184 R184B and R184W Supercardioid Cartridges

    Supercardioid cartridge for WL183, WL184, WL185 and all Microflex® MX183, MX202, MX391, MX392, MX393, MX405, MX410, MX415, MX412, and MX418 Microphones. White or Black.

    from $62.00

    RK100PK In-Line Preamplifier

    In-Line Preamplifier for Microflex Microphones. Boosts resistance to Radio Frequency Interference (RFI).

    from $119.00