Lectrosonics MM400b - Manual (Page 12)

POWER
LED
Modulation
LEDs
Power On/Off
Switch
positioning.
Antenna
Connector
Microphone Jack
Audio
Level
Control
MM400B
NOTE: All 400 Series (and a number of earlier
receivers) offer a front panel LCDs that indicate
the correct transmitter switch settings when
locating clear channels. Use the scanning
functions on these receivers to find a clear
channel, then switch both the receiver and
transmitter to the Frequency Select Switch settings
indicated in the receiver’s display.
If you are using a 100 Series receiver, turn off the
transmitter and observe the RF LED on the front panel
of the UCR100 receiver. If it flickers, or glows red, then
adjust the UCR100’s Frequency Select Switches up or
down in 100 kHz increments until the RF LED extin­
guishes. Set the MM400B transmitter’s Frequency
Select Switches to the same settings. Turn on the
transmitter and observe that the RF LED on the re­
ceiver glows brightly.
Attaching a Microphone and
Adjusting Audio Levels
The front panel Modulation LEDs indicate limiter activity.
(See chart.) Since the distortion introduced by the
limiter is minimal and full modulation is assured, occa­
sional forays into the red by the -10 LED is acceptable.
1) Install a fresh battery.
2) Insert the watertight microphone plug into the Mic
Jack and screw it in snugly.
WARNING: Do not overtighten as this will
distort the “O-ring” and allow moisture to enter
the unit.
3) Mute the main sound system and rotate the Audio
Level Control on the MM400B to maximum counter­
clockwise (Off).
4) Set the Power ON/OFF switch to the ON position.
5) Position the microphone in the location where it will
be used during in actual operation.
6) Observe the MM400B Modulation LEDS while
speaking or singing into the microphone at the
same voice level that will be used during the
program. Gradually rotate the Audio Level
Control control clockwise until both LEDs glow
green with the -20 dB occasional blinking red.
This indicates full modulation and is the
optimum setting for the transmitter’s gain.
Signal Level -20 LED -10 LED
Less than -20 dB Off Off
-20 dB to -10 dB Green Off
-10 dB to +0 dB Green Green
+0 dB to +10 dB Red Green
Greater than +10 db Red Red
NOTE: Different voices will usually require different
settings of the Audio Level Control, so check this
adjustment as each new person uses the system.
If several different people will be using the
transmitter and there is not time to make the
adjustment for each individual, adjust it for the
loudest voice.
7) Once the MM400B’s audio gain has been set, the
remaining components of the audio system can be
energized and adjusted.
WARNING: The AUDIO LEVEL control should
not be used to control the volume of your
sound system or recorder levels. This gain
adjustment matches the transmitter gain with
the user’s voice level and microphone
LECTROSONICS, INC. 12