Lectrosonics WM Watertight Belt-Pack Transmitter with Lavalier Mic (Block 21: 537.600 - 563.100 MHz)

Lectrosonics WM Watertight Belt-Pack Transmitter with Lavalier Mic (Block 21: 537.600 - 563.100 MHz)

Lectrosonics WM Watertight Belt-Pack Transmitter with Lavalier Mic (Block 21: 537.600 - 563.100 MHz)

Lectrosonics WM Watertight Belt-Pack Transmitter with Lavalier Mic (Block 21: 537.600 - 563.100 MHz)

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Expected availability: 7-10 business days

Product Highlights

  • For Broadcast, EFP and ENG Applications
  • Water-Resistant Seals
  • Selectable 50, 100 & 250 mW Output Power
  • LCD Interface with Lockout Option
  • Servo Bias Input Circuitry
  • Machined-Aluminum Housing
  • O-Ring Sealed Battery Compartment
  • Includes M152/WP Lavalier Mic
  • 2 x AA Batteries Included
  • Belt Clip
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Frequency Block: 21: 537-563 MHz

19: 486-511 MHz

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20: 512-537 MHz

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21: 537-563 MHz 22: 563-588 MHz

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23: 588-607, 614 MHz

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470: 470-495 MHz

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This item is noncancelable and nonreturnable.

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Lectrosonics WM/VT500WATER-21 overview

  • 1Description

The WM Watertight Belt-Pack Transmitter with Lavalier Mic from Lectrosonics is designed for wet or dusty environments. It features an O-ring sealed battery compartment and input jack, a compression sealed antenna port, and a gasket sealed control panel and back cover. It can be used when paired with a wireless receiver for capturing audio in broadcast TV, ENG (Electronic Field Productions), and EFP (Electronic Field Production) applications, and more.

Dual AA batteries provide twice the operating time of earlier watertight transmitter designs and the larger membrane switches and control panel have a highly visible backlit LCD, which enhances the user interface. In addition, there are 50, 100, or 200 mW selectable-output power switches to maximize battery life and operating range.

Some other features include servo bias input circuitry with selectable voltage for compatibility with other microphones, and programmable compatibility mode for use with a wide variety of different receivers. The transmitter is enclosed in a machined-aluminum corrosion resistant housing and includes a Lectrosonics M152/WP omnidirectional lavalier mic, a belt clip, an O-Ring kit, and two AA lithium batteries.

Servo Bias Input
The voltage and current requirements of the wide variety of electret microphones used in professional applications has caused confusion and compromises in the wiring needed for wireless transmitters. To address this problem, the Servo Bias input circuit provides an automatically regulated voltage over a very wide range of current for compatibility with all microphones
Digital Hybrid Wireless 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 companders for enhanced dynamic range, at the cost of subtle artifacts (typically “pumping” and “breathing”). 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

Digital Hybrid systems overcome channel noise by 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 compander but a technique that can be accomplished only in the digital domain, even though the inputs and outputs are analog

No Pre-Emphasis/De-Emphasis
The Digital Hybrid design results in a signal-to-noise ratio high enough to preclude the need for conventional pre-emphasis (HF boost) in the transmitter and de-emphasis (HF roll off) in the receiver. This eliminates the potential for distortion of signals with abundant high-frequency information
Low Frequency Roll-Off
The low frequency roll-off can be set for a 3 dB down point at 35, 50, 70, 100, 120 and 150 Hz to control subsonic and very low frequency audio content in the audio. The actual roll-off frequency will vary slightly depending upon the low frequency response of the microphone.
Excessive low frequency content can drive the transmitter into limiting, or in the case of high output sound systems, it can even cause damage to loudspeaker systems. The roll-off is normally adjusted by ear while listening as the system is operating
Input Limiter
A DSP-controlled analog audio limiter is employed before the A-D converter. The limiter has a range of more than 30 dB for excellent overload protection. A dual release envelope makes the limiter acoustically transparent while maintaining low distortion. It can be thought of as two limiters in series, a fast attack and release limiter followed by a slow attack and release limiter. The limiter recovers quickly from brief transients, with no audible side effects, and also recovers slowly from sustained high levels to keep audio distortion low while preserving short term dynamics
In the Box
Lectrosonics WM Watertight Belt-Pack Transmitter with Lavalier Mic (Block 21: 537.600 - 563.100 MHz)
  • M152/WP - Omnidirectional Lavalier Microphone with Watertight Connection
  • WMBCSL Spring-Loaded Machined Aluminum Clip for WM Transmitter
  • O-Ring Kit
  • 2 x AA Lithium Batteries
  • Limited 1-Year Warranty
  • Table of Contents
    • 1Description

    Lectrosonics WM/VT500WATER-21 specs

    Operating Frequency 537.600 - 563.100 MHz
    Channel Spacing 100 kHz
    Frequency Selection Control panel mounted membrane switches
    RF Power Output Switchable; 50, 100 or 250 mW
    Compatibility Modes Digital Hybrid Wireless (400 Series), 200 Series, 100 Series, Mode 3, Mode 6, IFB
    Pilot Tone 25 to 32 kHz; 5 kHz deviation (in 400 Series Mode)
    Frequency Stability ± 0.002%
    Deviation ± 75 kHz max. (In 400 Series Mode)
    Spurious Radiation 60 dB below carrier
    Equivalent Input Noise -125 dBV, A-weighted
    Input Level
    • If set for dynamic mic: 0.5 mV to 50 mV before limiting; greater than 1 V with limiting
    • If set for electret lavalier mic: 1.7 uA to 170 uA before limiting; greater than 5000 uA (5 mA) with limiting
    • Line level input: 17 mV to 1.7 V before limiting; greater than 5 V with limiting
    Input Impedance
    • Dynamic mic: 300 Ohms
    • Electret lavalier: input is virtual ground with servo adjusted constant current bias
    • Line level: >2.7 kOhms
    Limiter Soft limiter, 30 dB range
    Bias Voltage(s) Selectable 2 V, 4 V, and off
    Gain Range 44 dB; panel mounted membrane switches
    Modulation Dual bicolor LEDs indicate modulation of -20, -10, 0, +10 dB referenced to full modulation
    Controls Control panel with LCD and four membrane switches
    Low Frequency Roll-Off Adjustable from 35 to 150 Hz
    Audio Frequency Response 35 Hz to 20 kHz, +/-1 dB
    Signal to Noise Ratio SmartNR Off:
    • No Limiting: 103.5 dB
    • Limiting: 108 dB
    SmartNR Normal:
    • No Limiting: 107 dB
    • Limiting: 111.5 dB
    SmartNR Full:
    • 108.5 dB
    • 113 dB


    Total Harmonic Distortion 0.2% typical (400 Series mode)
    Audio Input Jack 0.1" (2.5 mm) locking micro; threaded for stainless sleeve on WP connector
    Antenna Flexible, unbreakable steel cable
    Batteries Two 1.5 Volt AA lithium recommended
    Battery Life
    • 50 mW: Lithium: 13 hours
    • 100 mW: Lithium: 10:45 hours
    • 250 mW: Lithium: 5:45 hours



    Emission Standard 180KF3E
    Dimensions 2.98 x 2.55 x 0.77" (75.7 x 64.8 x 19.6 mm)
    Weight 5.33 oz (151 g) with lithium batteries
    Packaging Info
    Package Weight 1.35 lb
    Box Dimensions (LxWxH) 9.9 x 7.8 x 2.9"

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