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Peer Review: Lectrosonics TM400

Peer Reviews: Lectrosonics TM400; Price: $1,890 MSRP

Lectrosonics TM400 digital hybrid wireless system

Price: $1,890 (MSRP)


Plus: Convenient, compact, and durable transmitter and receiver package; frequency selectable RF; includes compandor-free audio path and phantom power for test microphones

Minus: Some signal degradation compared to a standard mic cable; questionable durability of external power supply connector

AT SIA Acoustics, we use measurement microphones in a number of applications: measuring loudspeakers both in our lab and on job sites, setting up sound systems, and measuring room acoustics issues such as reverberation and ambient noise conditions. There are several issues that present problems for using standard wireless systems in critical measurement applications such as increased self noise, distortion, and noise artifacts due to companding deviations of frequency and phase response and range. However, the Lectronsonics unit successfully addresses most of these issues for all but the most extremely demanding situations.


The TM400 system consists of a UH400TM transmitter and R400 receiver. The receiver chassis design is compact, functional, and durable. The complete package, along with a measurement microphone, notebook computer, miscellaneous cables, adapters, etc. easily fits in a backpack or briefcase-type kit.

The UH400TM transmitter features the same type of “plug-on” design Lectrosonics is known for. It's small and durable, and includes a protective cordura case. It includes frequency, audio level, phantom, and power controls. Phantom power is selectable at 5, 18 or 48 V. The operating frequency is selected by turning two small pots with a miniature screwdriver.

The receiver is also small at about 5 1/2 inches wide, 6 1/4 inches deep, and 1 RU high. Two removable whip antennas are provided. The balanced XLR audio output level is variable from -50 to + 5 dBu. The receiver uses an external wall wart power supply and incorporates a locking-type chassis connector. Although the locking power connector is a good idea, this design's durability could be an issue because the locking features aren't obvious and lock into a fragile plastic receptacle.


The SmartTuning feature for finding clear frequencies is particularly quick and easy, especially because no external computer software is required. The Lectrosonics unit provides 256 different frequency options for its RF transmission — an increasingly important concern as HD television and other telecom applications crowd the wireless microphone system RF operating range. The SmartTuning feature uses the unit's receiver as a spectrum analyzer so users can quickly locate a clear band for operation and easily set up the receiver and transmitter for trouble-free use.

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