User Manual - RCVR
LR
LECTROSONICS, INC.
14
5) Set Up Transmitter to Matching Frequency 
 and Compatibility Mode
If you have not already set the frequency on the 
transmitter in the previous procedures, use IR Sync or 
complete the settings manually.
Lectrosonics transmitters with IR Sync:
On the LR receiver, navigate to IR Sync on the menu 
and press the MENU/SEL button. Hold the transmitter 
and receiver fairly close to each other (within two feet 
or so) and position them so the IR ports are facing one 
another. Press the UP arrow on the receiver to initiate 
the transfer of settings. The receiver will display a mes-
sage when the settings have been received.
Other transmitters: 
Frequency, input gain, etc, are set with the controls on 
the transmitter. The correct compatibility mode must 
also be selected on the receiver.
6) Adjust Transmitter Input Gain
NOTE: This adjustment is very important, since 
it will determine the signal to noise ratio and 
dynamic range that the system will deliver.
Lectrosonics transmitters with LCD interface:
The LEDs on the control panel provide an accurate 
indication of modulation level to assist in adjusting the 
input gain. The LEDs will glow either red or green to 
indicate modulation levels as shown in the following 
table. Full modulation is achieved at 0 dB, when the 
“-20” LED first turns red. The limiter can cleanly handle 
peaks up to 30 dB above this point.
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: It is best to go through the following 
procedure with the transmitter in the standby 
mode so that no audio will enter the sound 
system or recorder during adjustment.
1)  With fresh batteries in the transmitter and power 
the unit on in the standby mode (a brief press on 
the power switch with L-Series transmitters).
2)  Navigate to the Gain setup screen. 
Gain
LineIn
Freq.
ProgSw
-40
-20
0
Gain
25
3)  Prepare the signal source. Position a microphone 
the way it will be used in actual operation and have 
the user speak or sing at the loudest level that 
will occur during use, or set the output level of the 
instrument or audio device to the maximum level 
that will be used.
4)  Use the   and   arrow buttons to adjust the gain 
until the –10 dB glows green and the –20 dB LED 
starts to flicker red during the loudest peaks in the 
audio.
5)  Once the transmitter input gain has been set, the 
signal can be sent to the sound system or recorder 
for level adjustments, monitor settings, etc. 
6)  Do not use the transmitter input gain control to 
adjust the audio output level of the receiver.
Other Transmitters:
Earlier Lectrosonics transmitters provide LEDs to ac-
curately indicate full modulation, with continuously vari-
able gain controls for a precise adjustment. The LEDs 
operate in the same manner as those shown here for 
transmitters with an LCD interface.
The UM400A transmitter shown below is typical of 
many legacy Lectrosonics models.
LECTROSONICS
UM400a
OFF
ON
AUDIO
LEVEL
–10
–20
ANTENNA
Input gain 
control
Modulation 
level LEDs
Some transmitters from brands other than Lectroson-
ics can also be used if the appropriate compatibility 
mode set is set in the receiver. Observe the audio level 
meter on the LR receiver LCD as you adjust the input 
gain on the transmitter to see the modulation level. 
Some models may have limiters on the input to sup-
press overload distortion, and others may not. Monitor 
the audio, preferably with headphones, as you adjust 
the input gain to find the maximum level that can be 
set without audible limiting or overload distortion.










