GENERAL
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 applica-
tions.
FEATURES
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
MODEL VARIATIONS
MX391 and MX391W (white) models have an attached 4 meter
(12 ft) cable terminated with a 4-pin Tini Q-G
connector and a sepa-
rate preamplifier. A rubber strain relief is provided for applications
where you want to remove the Tini Q-G
connector and connect the
microphone cable directly to screw terminals in the preamplifier.
MX391LP and MX391WLP (white) models have an attached 4
meter (12 ft) cable terminated with a 4-pin Tini Q-G
connector, but
do not include a preamplifier. Instead, the microphone can be con-
nected directly to a Shure wireless body-pack transmitter.
Microflex
boundary microphones come with one of three inter-
changeable cartridges, as indicated by the model number (found on the
bottom of the microphone base).
MX391/C series
.
Cardioid pickup pattern for general sound rein-
forcement applications. Pickup angle (–3 dB) = 130
°
.
MX391/S series. Supercardioid pickup pattern for sound re-
inforcement applications requiring narrow or more distant cover-
age. Pickup angle (–3 dB) = 115
°
.
MX391/O series. Omnidirectional pickup pattern for recording
or remote monitoring applications. Pickup angle = 360
°
.
PERMANENT INSTALLATION
Screw holes in the microphone base and a bottom exit hole for
the microphone cable are provided for permanent installation of the
boundary microphone. To re-route the microphone cable through
the bottom exit hole, use the following steps (See Figure 1):
1.
Remove the grille from the microphone base by loosening the
single screw on top of the grille.
2.
Remove the Tini Q-G
connecter from the end of the cable by
cutting the cable just below the connector.
WARNING: Do not attempt to detach the cable from the micro-
phone interface.
3.
Secure the cable with your thumb or finger so that it does not
come loose from the strain-relief posts as you thread the cable
out from the rear exit hole.
4.
Re-route the cable through the bottom exit hole and pull snug.
IMPORTANT: Be sure the cable is pressed firmly down be-
tween the strain relief posts before replacing the grill.
5.
Set the grille back into place and thread the screw through the
perforated metal grille and into the microphone interface and
tighten.
6.
Use the supplied template (see Figure 5) to drill screw holes
and a bottom exit hole in the mounting surface.
7.
After threading the cable through the bottom exit hole in the
mounting surface, either re-attach the Tini Q-G
connector (see
Figure 2) or wire the cable to the screw terminals in the pream-
plifier (use the supplied rubber strain relief to secure the con-
nection).
NOTE: For detailed instructions on re-attaching the Tini Q-G
connector, contact the Shure Applications Group.
REPAINTING THE MX391 SERIES
Before applying paint to the MX391 series, remove the grille from
the base, remove the foam from the inside of the grill, and mask the
microphone cartridge and interface. Also mask the cable where
necessary.
Service Loop
Screw Hole
Screw Hole
Microphone Interface
Strain Relief Post
RE-ROUTING THE CABLE
FIGURE 1
Microflex
MX391 Series
Boundary Microphones User Guide
27B3027 (AD)
2001, Shure Incorporated
Printed in Mexico
