Lectrosonics UH400 User Manual download pdf (Page 6)

UH400

INPUT LIMITER

The 400 series transmitters employ a digitally-controlled analog

audio limiter just before the analog-to-digital converter. The

limiter has a range of more than 30dB for excellent overload

protection. A dual release envelope makes the limiter acousti-

cally transparent while maintaining low distortion. It can be

thought of as two limiters in series, connected as a fast attack

and release limiter followed by a slow attack and release limiter.

The limiter recovers quickly from brief transients, so that its

action is hidden from the listener, but recovers slowly from sus-

tained high levels, to both keep audio distortion low and preserve

short term dynamic changes.

The audio level LEDs indicate limiter activity. The first red LED

indicates that the limiter is active and that the transmitter is fully

modulated (audio level is between +0 and +10 dB). The second

red LED indicates that the level is 10dB or more into limiting.

Occasional forays into the red are desirable for most applica-

tions, since the distortion introduced by the limiter is so minimal,

and full modulation is thus assured. We strongly recommend

setting the gain of the transmitter high enough so that the first red

LED occasionally lights.

Generally speaking, some limiting is desirable in normal opera-

tion to improve the signal to noise ratio of the system. The

limiting action is not audible and does not create distortion. A

highly trained ear would hear only the compression of the peaks

in the audio signal, which is desirable with most recorders and

many sound reinforcement systems.

OPERATING MODE INDICATORS

The modulation LEDS will blink at power up to indicate the

selected operating mode. Immediately after powering up, all

LEDS will blink together red, then green, followed by the audio

level LEDs (-20 and -10) blinking to indicate the mode.

The –20 and –10 LEDs will blink:

• Once for 100 mode

• Two times for 200 mode

• Three times for mode 3

• Four times for 400 mode

MIC LEVEL

Used to adjust the audio input level for the proper modulation.

OPERATING INSTRUCTIONS

TO ATTACH

Press firmly, listen for click.

Depress collar fully.

Hold the

transmitter

case and

rotate the

collar in the

direction

shown. Do

this over a

soft surface

as the

microphone

may pop off

suddenly

Click!

Pull on mic to insure locking.

TO REMOVE

Attaching the Microphone

1. Insert the UH400 into the selected microphone. Listen for the

“click” that indicates the transmitter has locked on to the

microphone. Pull on the mic to insure proper locking has

occurred.

2. Turn the power switch on and, if necessary, enable phantom

power and select the proper voltage for your microphone.

3. Hold the microphone as you will when you will be using it.

4. Position the microphone in the location you will use in actual

operation.

5. While speaking or singing at the same voice level that will

actually be used, observe the MODULATION LEDs. Adjust

the MIC LEVEL control knob until the LEDs begin to light. At

too low a setting neither LED will light as you speak. Gradually,

turn the gain up until the –20 dB LED lights green and then the

-10 dB lights green. We strongly recommend setting the gain

of the transmitter even higher so that the first red LED

occasionally lights.

6. Once the gain has been adjusted, the audio system audio can

be turned on to make level adjustments in the main audio

system.

LECTROSONICS, INC.

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Lectrosonics UH400 User Manual Page 6

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