Handbook for Sound Engineers

Microphones 575

nates a compandor to increase audio quality and expand
the applications to test and measurement and musical
instrument applications.
Audio is sampled at 88.2 kHz and converted to a
24 bit digital stream. The DSP applies an encoding
algorithm that creates what might be likened to an
instruction set that is sent to the receiver via an FM
carrier. The DSP in the receiver then applies an inverse
of the encoding algorithm and regenerates the 24-bit
digital audio stream.
An additional benefit of the FM radio link is the
ability of the DSP to emulate a compandor for compati-
bility with analog receivers from Lectrosonics and two
other manufacturers.

In the native hybrid mode, the FM deviation is
±75 kHz to provide a wide dynamic range. This wide
deviation combined with 100 mW of output power
provides a significant improvement in the audio SNR
and the suppression of RF noise and interference.

Used with a microphone, the antenna is a dipole
formed between the transmitter housing and the micro-
phone body. When plugged into a console or mixer
output, the housing of the transmitter is similar to the
radiator of a ground plane antenna, with the console or
mixer chassis functioning as the ground.

Phantom power can be set to 5, 15,or 48 V or turned
off. The transmitter can provide up to 15 mA of current
in 5 and 15 V settings, and up to 7 mA in the 48 V

setting, allowing it to be used with any type of micro-

phone, including high-end studio condenser models.

The transmitter is available on 9 different frequency

blocks in the UHF band between 470 and 692 MHz.

Each block provides 256 frequencies in 100 kHz steps.

16.12.1.5 MXL Mic Mate™ USB Adapter

The Mic Mate™, Fig. 16-160, is a USB adapter used to

connect a microphone to a Macintosh or PC computer.

It uses a 16 bit Delta Sigma A/D converter with

THD+N= 0.01% at sampling rates of 44.1 and

48.0 kHz and includes a three-position analog gain

control. It includes a studio-quality USB microphone

preamp with a balanced low noise analog input,

supplies 48 Vdc phantom power to the microphone, and

includes MXL USB Recorder Software for two track

recording. There are three different Mic Mates, one for

condenser microphones, one for dynamic microphones,

and one for news line feeds, video cameras, etc.

Figure 16-159. Block diagram of the Lectrosonics UH400A transmitter. Courtesy Lectrosonics, Inc.

Figure 16-160. MXL Mic Mate USB adapter. Courtesy

Marshall Electronics.