Shure Microflex® MX391 Series microphones are small, surface-mounted electret condenser microphones designed for mounting on conference tables, stage floors, and lecterns. Their high sensitivity and wide frequency range make them especially suitable for picking up speech and vocals in sound reinforcement and recording applications.
Microflex MX391 microphones are available in black or white.
The polar pattern of the included cartridge is indicated by a model number suffix:
/C Cardioid
/S Supercardioid
/O Omnidirectional
/N Cartridge not included
Microflex microphones use interchangeable cartridges that allow you to choose the polar pattern for different installations.
Cartridge Polar Patterns
Important: Microphones must be used with the RK100PK or RK202PK plate-mounted preamp to optimize RF immunity.
For best low-frequency response and rejection of background noise, place the microphone on a large, flat surface, such as a floor, table, or lectern.
To reduce reverberance, avoid reflective surfaces above or to the side of the microphone, such as beveled sides of pulpits or overhanging shelves.
Do not attempt to detach the cable from the microphone, as damage may result.
If necessary, the preamplifier gain can be reduced by 12 dB. Contact an authorized Shure service center for information.
All measurements taken with microphone mounted on a wooden surface (76 x 76 cm)
Electret Condenser
50–17000 Hz
| MX391/C | Cardioid |
| MX391/S | Supercardioid |
| MX391/O | Omnidirectional |
180 Ω
Active Balanced
@ 1 kHz, open circuit voltage
| Cardioid | –30 dBV/Pa(33.5 mV) |
| Supercardioid | –28 dBV/Pa(38.5 mV) |
| Omnidirectional | –22 dBV/Pa(81.4 mV) |
1 Pa=94 dB SPL
1 kHz at 1% THD, 1 kΩ load
| Cardioid | 119 dB |
| Supercardioid | 118 dB |
| Omnidirectional | 111 dB |
A-weighted
| Cardioid | 23 dB SPL |
| Omnidirectional | 15 dB SPL |
| Supercardioid | 21 dB |
Ref. 94 dB SPL at 1 kHz
| Cardioid | 71 dB |
| Omnidirectional | 80 dB |
| Supercardioid | 73 dB |
1 kΩ load, @ 1 kHz
96 dB
45 dB, minimum
at 1% THD
–6 dBV (0.5 V)
Positive sound pressure on diaphragm produces positive voltage on pin 2 relative to pin 3 of output XLR connector
| Operating Temperature | –18–57°C (0–135°F) |
| Storage Temperature | –29–74°C (–20–165°F) |
| Relative Humidity | 0–95% |
11–52 V DC, 2.0 mA
Microphone Wiring Diagram
Note: Yellowing of any plastic material can be caused from cigarette smoke, ultra violet rays, and other chemical interactions. Once plastic has yellowed, there typically is no cleaning method that will restore the whiteness.
| Carrying/Storage Bag | 95A2313 |
| RFI Resistant, Inline Preamp for all MX Models (Black) | RK100PK |
| Allen wrench (No. 4) | 80A67 |
Meets essential requirements of all applicable European Directives.
Eligible for CE marking.
The CE Declaration of Conformity can be obtained from Shure Incorporated or any of its European representatives. For contact information please visit www.shure.com
The CE Declaration of Conformity can be obtained from: www.shure.com/europe/compliance
Authorized European representative:
Shure Europe GmbH
Headquarters Europe, Middle East & Africa
Department: EMEA Approval
Jakob-Dieffenbacher-Str. 12
75031 Eppingen, Germany
Phone: +49-7262-92 49 0
Fax: +49-7262-92 49 11 4
Email: info@shure.de
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