Lectrosonics H175DC - Manual (Page 7)

Plug-On Transmitter
2) Turn on the receiver and adjust the output level to minimum.
3) Turn on the transmitter. The CODE LED on the receiver should come on.
4) Hold the microphone as you will when you will be using it.
5) Speak as loudly as you expect to speak in normal system use. Adjust the MIC LEVEL on the transmitter so that
the LEVEL LED on the receiver flickers or stays lit as you speak. The LIMIT LED on the receiver should light up
on loud “peaks.” (The Level LED may be labeled as “-20” and the Limit LED may be labeled as “0dB.”)
Occasional lighting of the LIMIT LED (about 10-15% of the time) indicates proper operation
and optimum signal-to-noise ratio.
Even when the transmitter is limiting, little distortion is produced because of the high linearity of the gain control
circuit in the H175.
6) Adjust the receiver output level as necessary.
It is possible for the system to appear to be “locked-up” and not working. This can happen if the transmitter is
turned on while out of range of the receiver or if the transmitter is turned on before the receiver. If this happens,
the receiver never gets the code that tells it to “turn on.” The cure is simple. Move the transmitter into range of the
receiver and turn it off then back on. You can always tell if the receiver is enabled by looking at the CODE LED. If
the LED is on, the receiver is enabled and ready for use.
NOTE:
The LEVEL control on the transmitter should not be used to control the volume of your sound system. This should be
done using the level control on the receiver, or a level control on the mixing console.
If the mic level is too high - the LIMIT LED on the receiver will light frequently or stay on. This condition may cause
distortion.
If the mic level is too low — neither LED will light, or the LEVEL LED (on the receiver) will light dimly. This condition
will cause hiss and noise. You may experience severe reduction in apparent range if the modulation level is too low. It
may sound as if you are getting dropouts. What is actually happening is that you are hitting your noise floor because
the S/N ratio has been reduced by the low modulation.
The input compressor operates over a full 30dB 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.
SETUP FOR OLDER RECEIVERS
This transmitter features the new Wide Range Limiting circuitry to prevent input overload during loud peaks. When
used with receivers that have not been adjusted for this limiter, the Modulation LEDs on the receiver control panel may
not function as indicated above. Audio peaks are indicated by an LED labeled “0dB” or “LIMIT” on the receiver (red
LED on the Long Ranger). If this LED on your receiver will not light even with loud audio peaks and the transmitter
gain set at maximum, use the instruction in the following paragraph to adjust the transmitter input gain.
Follow the procedure described in step 5 above except adjust the gain control so that the
“LEVEL” or “-20” LED on the receiver (green LED on the Long Ranger) lights up about 50%
of the time while you are speaking.
The net result of this adjustment will produce essentially the same results as the setup procedure described in the
manual. There is no loss of performance in the wireless system using this procedure.
Receivers can be adjusted at the factory to work with the new Wide Range Limiting circuitry. The adjustment to the
receiver is simply to set the “LIMIT” or “0dB” LED threshold slightly lower so that it will indicate peaks in the audio.
There is no difference in the audio quality whether or not the receiver LEDs are adjusted for the new limiting circuitry.
If you have questions, or would like to arrange for the factory to adjust your receiver, call (800) 821-1121 and ask for
the service department.
Rio Rancho, NM – USA 7