10
LM
LECTROSONICS, INC.
The wiring diagrams shown in Wiring Hookups For Different Sources represent the basic wiring configurations
necessary for the most common types of microphones and other audio inputs. Some microphones may require extra
jumpers or a slight variation in the diagrams shown.
It’s virtually impossible to keep completely up to date on changes that other manufacturers make to their products. It
is possible that you may encounter a microphone that differs from those illustrated. If this occurs please call our toll-
free number listed in the back of this manual for assistance. Our Service Department can answer your questions
regarding microphone compatibility.
When used on a wireless transmitter, the microphone element is in the proximity of the RF coming from the transmit-
ter. The nature of electret microphones makes them sensitive to RF, which can cause problems with the microphone/
transmitter compatibility. If the electret microphone is not designed properly for use with wireless transmitters, it may
be necessary to install a chip capacitor in the mic capsule or connector to block the RF from entering the electret
capsule. (See RF Bypassing.)
PIN 1
Shield (ground) for positive biased electret lavalliere microphones. For the increasingly
rare negative biased electret lavalliere microphones, it is the bias voltage source. It is
also the shield (ground) for dynamic microphones and line level inputs.
PIN 2
Shield (ground) for negative biased electret lavalliere microphones. Bias voltage source
for positive biased electret lavalliere microphones.
PIN 3
Low impedance microphone level input for dynamic microphones. Also accepts hand-
held electret microphones that have their own battery or power supply.
PIN 4
4 k Ohm source load for non-Lectrosonics electret microphones. Use in conjunction with
other pins to provide attenuation of high level input signals.
PIN 5
40 k high impedance, line level input for tape decks, mixer outputs, musical instruments,
etc.
RF BYPASSING
Some mics require RF protection to keep the transmit-
ter signal from affecting the capsule, even though the
transmitter input circuitry is already RF bypassed (see
5-Pin Input Jack Wiring schematic diagram above).
If the mic is wired as directed, and you are having
difficulty with squealing, high noise, or poor frequency
response, RF is likely to be the cause.
The best RF protection is accomplished by installing
330 pF bypass capacitors at the mic capsule. If this is
not possible, or if you are still having problems,
3 WIRE MIC
2 WIRE MIC
CAPSULE
CAPSULE
SHIELD
AUDIO
SHIELD
AUDIO
BIAS
TA5F
CONNECTOR
TA5F
CONNECTOR
Preferred locations for bypass capacitors
Alternate locations for bypass capacitors
5-PIN INPUT JACK WIRING
4
3
2
1
5
LECTROSONICS
FB
40k
4k
5
100
4
3
2
1
+
5V Mic Bias
To Mic Amp
POS BIAS (OR GND)
MIC
SOURCE LOAD
LINE IN
NEG GND (OR BIAS)
+
1k
10uF
330pF
330pF
330pF
330pF
LM Front Panel
Input Jack
Input Circuit
