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Biamp Systems

Connecting a Shure MX396 to a Logic Box

One popular application for the Logic Box or Voltage Control Box is to interface with conferencing microphones that feature mute switches and LED indicators, and Shure is a leading manufacturer of such microphones. This article describes how to physically connect a Shure MX396 microphone to a Biamp Logic Box.

Goal

After completing the steps in this article, you will be able to connect a Shure MX396 to a Biamp Logic Box.  This will allow your Audia or Nexia configuration to control the LED's on the MX396, and it will also allow the mic's mute switch to control functions within your Audia or Nexia configuration (like mic muting).

Note that Shure MX series microphones use phantom power to power its LED's.  Therefore, no external power supply is required for this application.

Conductor colors

The Shure MX396 is a multi-element boundary microphone with a mute switch and a bi-color LED.  The MX396 comes with a unterminated cable containing all audio and logic conductors.  The conductor color code for this cable is as follows:

Conductor Color Function
White Audio 1 +
Green Audio 1 -
Orange Audio 2 +
Blue Audio 2 -
Yellow Audio 3 + (TRI models only)
Gray Audio 3 - (TRI models only)
Shield Audio ground
Black LED In
Red Switch contact
Silver (non-insulated) Logic ground

Wiring

The audio conductors on the microphone will connect to audio inputs on the Audia/Nexia like a typical microphone.  Note that each capsule on the microphone requires its own dedicated input, so the MX396 will use two or three inputs per microphone (depending on whether the mic is a DUAL or TRI model).  The LED and switch conductors will connect to the Logic Box.  The LED In (black) conductor connects to a logic output, and the Switch Contact (red) connects to a logic input.

Each MX396 uses two I/O terminals on the Logic Box, meaning that a maximum of 10 MX396's can be connected to a single Logic Box.  The diagram below shows a typical wiring scheme for a single MX396.  The wiring shown is for a TRI model microphone, a DUAL model would omit the yellow and gray conductors.

mx396.jpg

DIP switches

DIP switch 3 should always be in the UP position to ensure that the mic is not locally muted when the mute switch is pressed.  

If DIP switch 1 is in the UP position, the mute switch will behave like a toggle switch.  If DIP switch 1 is in the DOWN position, the mute switch will behave like a momentary switch.

LED control

The LED ring will light up green when there is less than 1V across the black and silver conductors (i.e., logic output in the low state), and it will light up red when there is 5V across the black and silver conductors (i.e., logic output in the high state).

Further reading

Once the device is physically connected to the Logic Box, you'll need to program it.  See Logic Box Programming for more information.

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