Lectrosonics UM450L, UM450M, UM450H, UM450V User Manual
UM450
Frequency-Agile UHF Belt-Pack Transmitter
INSTRUCTION MANUAL
Featuring
Digital Hybrid Wireless™ Technology
(US Patent Pending)
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Rio Rancho, NM, USA
www.lectrosonics.com
UM450
LECTROSONICS, INC.2
Frequency-Agile UHF Belt-Pack Transmitter
Thank you for selecting the Lectrosonics UM450 frequency agile, belt-pack transmitter. The UM450 combines over 80
years of engineering experience with the very latest components, in a design that addresses the most demanding
professional applications.
The design of the UM450 was the direct result of numerous conversations with users, staging and touring companies
and dealers across the US. The specific concerns and needs brought up in these conversations led directly to the
development of the operational features offered on the UM450. Two hundred fifty six frequencies are user selectable in
100kHz steps to alleviate interference problems in traveling venues, and the low frequency roll-off is user adjustable to
adapt to varying acoustic environments and preferences.
The UM450 is a rugged, machined aluminum package with a removable, spring loaded belt clip. The input section
provides a correct input tap for virtually any microphone or line level audio source. Five volts of bias voltage is available to power electret mics with either positive or negative bias. Level indicating LEDs are provided on the control
panel to make level settings quick and accurate, without having to view the receiver. The battery compartment accepts any 9 Volt alkaline battery and makes a positive connection via self-adjusting contacts. The antenna is a detachable, locking 1/4 wavelength flexible galvanized steel cable that connects to a 50 Ohm SMA port on the transmitter.
Only the UM450 transmitter is covered in this manual. Companion receivers are covered in separate manuals. The
UM450 will operate with any 400 Series Lectrosonics receiver and a variety of analog receivers in the same frequency
group.
Rio Rancho, NM 3
UM450
LECTROSONICS, INC.4
Frequency-Agile UHF Belt-Pack Transmitter
Table of Contents
General Technical Description ..............................................................................................................................................................6
Introduction ...........................................................................................................................................................................................6
Digital Hybrid Technology .....................................................................................................................................................................6
UM450 Block Diagram.......................................................................................................................................................................... 6
No Pre-Emphasis/De-Emphasis ........................................................................................................................................................... 7
Pilot Tone Squelch ................................................................................................................................................................................ 7
Input Limiter .......................................................................................................................................................................................... 7
Wide-Band Deviation ............................................................................................................................................................................7
Long Battery life ...................................................................................................................................................................................7
Frequency Agility .................................................................................................................................................................................. 7
Antenna ................................................................................................................................................................................................7
Controls and Functions .........................................................................................................................................................................8
Input Jack .............................................................................................................................................................................................8
Power ON/OFF Switch ......................................................................................................................................................................... 8
Power On LED ...................................................................................................................................................................................... 8
Audio Level Control ..............................................................................................................................................................................8
Audio Level ...........................................................................................................................................................................................8
Modulation LEDs ..................................................................................................................................................................................9
Antenna ................................................................................................................................................................................................9
Frequency Select Switches ..................................................................................................................................................................9
Adjustable Low Frequency Roll-Off ......................................................................................................................................................9
Belt Clip ................................................................................................................................................................................................9
Battery Installation ............................................................................................................................................................................... 10
Operating Instructions ........................................................................................................................................................................10
Selecting the Compatibility Mode .......................................................................................................................................................10
Attaching a Microphone and Adjusting Gain ...................................................................................................................................... 11
Operating Notes ................................................................................................................................................................................. 11
Adjusting the Transmitter Frequency .................................................................................................................................................. 11
Microphone Cord Termination ............................................................................................................................................................ 12
TA5F Connector Assembly .................................................................................................................................................................12
Mic Cord Stripping Instructions ..........................................................................................................................................................12
5-Pin Input Jack Wiring ........................................................................................................................................................................ 13
Input Jack Wiring Diagram.................................................................................................................................................................. 13
RF Bypassing .....................................................................................................................................................................................13
Line Level Signals .............................................................................................................................................................................. 14
Wiring Hookups for Different Sources ...............................................................................................................................................15
Replacement Parts and Accessories ................................................................................................................................................. 16
UHF Transmitter Antenna Specifications ............................................................................................................................................16
Troubleshooting ...................................................................................................................................................................................17
Specifications and Features ............................................................................................................................................................... 18
Service and Repair ...............................................................................................................................................................................19
Returning Units for Repair ..................................................................................................................................................................19
Rio Rancho, NM 5
UM450
General Technical Description
Introduction
The 400 system uses 75 kHz wide deviation for an
extremely high signal to noise ratio. The switching
power supplies provide constant voltages to the transmitter circuits from the beginning (9.3 Volts) to the end
(5.5 Volts) of battery life. The input amplifier uses an
ultra low noise op amp for quiet operation. It is gain
controlled with a wide range dual envelope input
compressor which cleanly limits input signal peaks over
30 dB above full modulation.
Digital Hybrid Technology
All wireless links suffer from channel noise to some
degree, and all wireless microphone systems seek to
minimize the impact of that noise on the desired signal.
Conventional analog systems use compandors to
improve the signal to noise ratio, at the cost of subtle
artifacts (known as “pumping” and “breathing”). Wholly
digital systems defeat the noise by sending the audio
information in digital form, at the cost of some combination of power, bandwidth and resistance to interference.
The Lectrosonics Digital Hybrid system overcomes
channel noise in a dramatically new way, digitally
encoding the audio in the transmitter and decoding it in
the receiver, yet still sending the encoded information
via an analog FM wireless link. This proprietary algorithm is not a digital implementation of an analog
compandor but a technique which can be accomplished
only in the digital domain, even though the inputs and
outputs are analog signals. (As of this writing, the
patent is still pending, so we cannot reveal detailed
information about the algorithm at this time.)
Channel noise still has an impact on received signal
quality and will eventually overwhelm the receiver. The
Digital Hybrid simply encodes the signal to use a noisy
channel as efficiently and robustly as possible, yielding
audio performance that rivals that of wholly digital
systems, without the power and bandwidth problems
inherent in digital transmission. As always, these
advantages come at a cost. The Digital Hybrid system
requires fairly intensive digital processing in both the
transmitter and the receiver. These processors cost
money, take up space and consume power. The Digital
Hybrid system also requires that the underlying RF link
be of excellent quality, with better frequency response
and distortion characteristics than that required by
conventional systems.
Because it uses an analog FM link, the Digital Hybrid
enjoys all the benefits of conventional FM wireless
systems, such as excellent range, efficient use of RF
spectrum, and long battery life. However, unlike conventional FM systems, the Digital Hybrid has done away
with the analog compandor and its artifacts.
UM450 Block Diagram
<--See
5-Pin Input Jack Wiring
for details.
LECTROSONICS, INC.6
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