Lectrosonics T187 - Manual (Page 8)

OPERATING INSTRUCTIONS
1) Install a fresh battery according to the instructions on page 7.
2) Move the internal bypass slide switches to the left-hand position so that the battery status LED and the bottom
panel switches will operate.
3) Move the “A” (audio) switch to “OFF” and the “P” (power) switch to ON (in that order). Observe that the battery
status LED is brightly lit. If the LED is dim, replace the battery.
4) Hold the microphone in the same position that will be used in actual operation.
5) While speaking or singing at the same voice level that will be actually used, observe the MOD LEVEL LEDs on
the PC board. Adjust the AUDIO LEVEL control knob until the LEDs begin to light. The first LED lights when the
audio level is about 10 dB below full modulation and limiting. The second LED (closest to the knob) lights when
the limiter begins to operate. There is 20 dB of headroom above the limiter LED and it is normal that it lights up
5% to 10% of the time during use.
5) Once the gain has been adjusted, the transmitter audio can be turned on to make sound system level adjust­
ments. Operate the “A” (audio) switch to ON position and adjust the receiver and/or sound system level as
required.
OPERATING NOTES
The AUDIO LEVEL control knob should not be used to control the volume of your sound system. This gain adjust­
ment matches the transmitter gain with the user’s voice level and microphone positioning.
If the mic level is too high both LEDs will light frequently or stay lit. This condition may cause distortion.
If the mic level is too low neither LED will light, or the LEVEL LED will light dimly. This condition will cause hiss and
noise along with the audio.
The first LED turns on at -10dB below full deviation. The limiting LED (closest to the knob) turns on at full deviation
and indicates that the input shunt compressor is operating. The input compressor operates over a full 20dB range
regardless of the gain control setting. The compressor uses a true absolute value circuit to detect both positive and
negative peaks. The attack time is 2 milliseconds and the release time is 80 milliseconds. Occasional limiting is
desirable, indicating that the gain is correctly set and the transmitter is fully modulated for optimum signal to noise
ratio.
Different voices will usually require different settings of the AUDIO LEVEL control, so check this adjustment fre­
quently. If several different people will be using the T187 and there is not time to make the adjustment for each
individual, adjust it for the loudest voice.
8