Getting Started: Transmitter Mic Closure Configuration

This article will cover Mic Closures, what they are, why they are necessary and the typical types.  The Futuri POST transmitters require a dry latched closure to ensure proper talk break segmentation.

What is a "Mic Closure"? - A mic closure is a trigger that signals the Futuri Encoder that the microphone is live. (Mic Closures can be a physical connection to the station's  "On-Air" light.)

Why is it necessary to have "Mic Closures"? - Mic closures are important for POST to determine when the mic is live. By sending the mic closure to the encoder, POST is able to accurately break the audio into correct segments, allowing the end user to more efficiently create postable content.

What is a "GPIO"? - You will occasionally hear Mic Closures referred to as GPIOs. A GPIO or (General Purpose Inputs and Outputs) are physical hardware connections that allow computers to interact on a software level. (The Futuri Encoder in this instance.)

Types of Mic Closures:

Types of Mic Closures
Description of Closure

Gen4 Single Stream Boxes:
The Gen4 Single stream boxes have their GPIO connection incorporated into the DB15HD connector that also connect analog audio to the encoder.
  • The engineer will connect wires from pins 6 and 5 (GND) to an open pair on the electrical relay that switches the "On-Air" lights to the "ON" position.

DB15HD Connector
Gen4 Multi-Stream Boxes: 

The Gen4 Multi-stream Encoder or (MSE), has a DB15 connector on the back of the box.  The MSE is unique,  in that each station, or slot on the box may have two separate GPIO connections.  This will allow for the "On-Air" lights from two different studios to trigger a Mic Closure from within the POST System.

  • Station 1 or "Slot 1" uses Pin 1 through Pin 15 (GND) for the first GPIO and, Pin 2 through Pin 15 for the second. 
  • Station 2 uses Pin 3 through Pin 15 for the first GPIO and, Pin 4 through Pin 15 for the second.
  • Station 3 uses Pin 5 and, 6 through Pin 15.
  • Station 4 uses Pins 7 and, 8 through Pin 15.

DB15 connector


1Station 1Closure 1

Station 1 

Closure 2

Station 2

Closure 1
4Station 2Closure 2
5Station 3Closure 1
6Station 3Closure 2

Station 4 

Closure 1
8Station 4Closure 2

Axia Closures:

Axia closures work by listening to a Port and Pin on an xnode device. For the Axia closure to work properly, we will need:

  • The IP address of the xnode device, and 
  • The Port and Pin numbers.

Axia Closer
"Stop Block" Closures:

"Stop Block" closures are basically inverted closures. Instead of sending a signal when the mic is in the "ON" or "Off" position, the system sends a signal before and after a commercial break occurs.  For this reason "Stop Block" closures are generally on used on Talk radio stations.

Serial Closures - Gen3 Boxes:
The serial connections on a Gen3 box are made by connecting a female DB9 adapter to a 9 pin serial port on the back of the unit.
  • These adapters have a 4.7 resistor between pins 1 and 4. The engineer will connect wires from pins 1 and 5 to an open pair on the electrical relay that switches the "On-Air" lights to the "ON" position.
  • An electrical relay is a device that allows a low voltage circuit to trigger a high voltage circuit. For example, unmuting a microphone on a console is a low voltage circuit. The On-Air light turning on is a high voltage circuit. 
  • The relay allows the low voltage circuit to trigger the high voltage circuit, while keeping the sides electrically separated. The connection must be made on the low voltage side of the relay.

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