MX391
Surface Mount Microphones
The Shure small, surface-mounted electret condenser microphone series, MX391, user guide.
Version: 5 (2019-J)
Table of Contents
MX391Surface Mount Microphones 3
General Description 3
Model Variations 3
Interchangeable Cartridges 3
RFI Filtering 4
Shure Incorporated
Microphone Placement 4
Permanent Installation 4
Preamp Gain 5
Specifications 5
Furnished Accessories 7
Certifications 7
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MX391 Surface Mount Microphones
General Description
Shure Microflex MX391 Series microphones are small, surface-mounted electret condenser microphones designed for mount-
ing on conference tables, stage floors, and lecterns. Their high sensitivity and wide frequency range make them especially suit-
able for picking up speech and vocals in sound reinforcement and recording applications.
•
Flat frequency response across the vocal range for uncolored sound
•
Interchangeable cartridges that provide a choice of polar pattern for each application
•
Sleek, low-profile design for unobtrusive appearance
•
RF filtering
®
Model Variations
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
Interchangeable Cartridges
Microflex microphones use interchangeable cartridges that allow you to choose the polar pattern for different installations.
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RFI Filtering
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Cartridge Polar Patterns
Important: Microphones must be used with the RK100PK or RK202PK plate-mounted preamp to optimize RF immunity.
Microphone Placement
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.
Permanent Installation
1.
Remove grille.
2.
Place housing in position and mark location of screw holes and bottom cable exit hole.
3.
Drill starter hole for each screw and a 1/2 in. bottom exit hole for the mic cable.
4.
Insert 4-pin mini-connector and cable through cable hole.
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5. Replace grille with screw. Do not overtighten.
Do not attempt to detach the cable from the microphone, as damage may result.
Preamp Gain
If necessary, the preamplifier gain can be reduced by 12 dB. Contact an authorized Shure service center for information.
Specifications
All measurements taken with microphone mounted on a wooden surface (76 x 76 cm)
Type
Electret Condenser
Frequency Response
50–17000 Hz
Polar Pattern
MX391/C Cardioid
MX391/S Supercardioid
MX391/O Omnidirectional
Output Impedance
180 Ω
Output Configuration
Active Balanced
Sensitivity
@ 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
Maximum SPL
1 kHz at 1% THD, 1 kΩ load
Cardioid 119 dB
Supercardioid 118 dB
Omnidirectional 111 dB
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Self Noise
A-weighted
Cardioid 23 dB SPL
Omnidirectional 15 dB SPL
Supercardioid 21 dB
Signal-to-Noise Ratio
Ref. 94 dB SPL at 1 kHz
Cardioid 71 dB
Omnidirectional 80 dB
Supercardioid 73 dB
Dynamic Range
1 kΩ load, @ 1 kHz
96 dB
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Common Mode Rejection
45 dB, minimum
Clipping Level
at 1% THD
–6 dBV (0.5 V)
Polarity
Positive sound pressure on diaphragm produces positive voltage on pin 2 relative to pin 3 of output XLR
connector
Environmental Conditions
Operating Temperature –18–57°C (0–135°F)
Storage Temperature –29–74°C (–20–165°F)
Relative Humidity 0–95%
Power Requirements
11–52 V DC, 2.0 mA
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Microphone Wiring Diagram
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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.
Furnished Accessories
Carrying/Storage Bag 95A2313
RFI Resistant, Inline Preamp for all MX Models (Black) RK100PK
Allen wrench (No. 4) 80A67
Certifications
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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