Model 374A Intercom Beltpack User Guide Issue 3, August 2019 This User Guide is applicable for serial numbers M374A-02501 and later with application firmware 1.3 and later Copyright © 2019 by Studio Technologies, Inc., all rights reserved www.studio-tech.
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MODEL 374A INTERCOM BELTPACK Table of Contents Revision History ............................................................ 4 Introduction ................................................................... 5 Getting Started .............................................................. 8 Operation ...................................................................... 13 Technical Notes ............................................................. 18 Specifications .........................................
MODEL 374A INTERCOM BELTPACK Revision History Issue 3, August 2019: 1. Documents revision to STcontroller (version 2.02.00 and later) which separates microphone power and microphone gain configuration. Issue 2, April 2019: 1. Documents new receive and send call function. Issue 1, June 2018: 1. Initial release. Issue 3, August 2019 Page 4 Model 374A User Guide Studio Technologies, Inc.
MODEL 374A INTERCOM BELTPACK Introduction The Model 374A Intercom Beltpack begins with the features offered by traditional party-line intercom user devices and adds a range of new capabilities along with the advanced performance and flexibility that Dante® audio-over-Ethernet provides. With four independent talk and listen channels the Model 374A bridges the gap between typical single- and dualchannel party-line devices and permanently installed multi-channel intercom panels.
MODEL 374A INTERCOM BELTPACK The audio quality of the Model 374A’s four audio channels is excellent, with low distortion, low noise, and high headroom. Careful circuit design and rugged components ensure long, reliable operation. A wide range of applications can be supported, including sports and entertainment TV and radio events, streaming broadcasts, corporate and government AV installations, and post-production facilities.
MODEL 374A INTERCOM BELTPACK to indicate to users that they are needed “on headset” or should be actively listening to an intercom channel. The call function can also be used to provide realtime cues to production personnel during the running of live events. Call signals present on the four audio input (Dante receiver) channels can be detected and displayed. Pushbutton 4, on the Model 374A’s top panel, can be configured to serve as a call button.
MODEL 374A INTERCOM BELTPACK Future Capabilities and Firmware Updating The Model 374A was designed such that its capabilities and performance can be enhanced in the future. A USB connector, located on the unit’s main circuit board (underneath the unit’s cover), allows the application firmware (embedded software) to be updated using a USB flash drive. The Model 374A uses Audinate’s Ultimo™ integrated circuit to implement the Dante interface.
MODEL 374A INTERCOM BELTPACK left earpiece to pin 5 of the XLR connector and the right earpiece to pin 4. If this condition is present it will require reversing or “flipping” the two wires in a headset’s 5-pin male XLR connector such that the left earpiece connects to pin 4 and the right earpiece to pin 5. Dante Configuration Figure 2. Headset connection pinout chart connection. No support is provided for microphones that require P12 or P48 phantom power.
MODEL 374A INTERCOM BELTPACK The four Dante receiver (Rx) channels associated with the Model 374A’s audio inputs also need to be routed to the desired Dante transmitter (Tx) channels. These four audio signals can be sent to the Model 374A’s 2-channel headphone output. The Model 374A supports an audio sample rate of 48 kHz with no pull-up/pull-down values available.
MODEL 374A INTERCOM BELTPACK configuration menu to appear. Review the current configuration and make changes as required. Microphone Input – Electret Power Choices are Enabled or Disabled. If the headset has an electret microphone that requires a source of low-voltage DC power for operation enable the Electret Power check box. If the associated headset has a dynamic (non-powered) microphone do not enable the Electret Power check box.
MODEL 374A INTERCOM BELTPACK input sources to be routed to both the left and right channels. But the Model 374A’s flexibility allows each source to be independently configured for sending to the left only, right only, or both left and right headphone channels. When using a stereo headset sending all inputs to both channels is often referred to as a dual-channel mono output.
MODEL 374A INTERCOM BELTPACK instead control the on/off state of the audio being sent to the headphone output. In this mode talk audio will never be sent out the associated Dante transmitter channel. This is an interesting mode, allowing one or more Model 374A audio channels to serve in a “monitor mixer” function. The button will allow quick on/off control while the rotary level control can remain in its desired position.
MODEL 374A INTERCOM BELTPACK has started. Once the entire sequence has completed and the Dante connection has been established full operation will begin. Ethernet and Dante Status LEDs Three status LEDs are located below the etherCON RJ45 receptacle on the Model 374A’s bottom panel. The LINK ACT LED will light green whenever an active connection to a 100 Mb/s Ethernet network has been established. It will flash in response to Ethernet data packet activity.
MODEL 374A INTERCOM BELTPACK the four talk channels does not impact the headphone output. However, one button configuration setting (Talk Disabled/Phone Tap to Latch) assigns the associated button to function as a channel listen audio on/off selector. Button Operation Four pushbutton switches are associated with the Model 374A’s four channels. How they function will depend on the configuration of the unit. Each button can be configured independently.
MODEL 374A INTERCOM BELTPACK will always be sent to both headphone channels and is not a configurable choice. This is because the function is trying to simulate what a user would hear if they didn’t have a headset covering their ears. It is not intended to indicate to the user which Dante audio output (transmitter) channel or channels are actively sending audio. The exact sidetone level is configured from among five values within the STcontroller application.
MODEL 374A INTERCOM BELTPACK Whenever a Model 374A audio input channel receives a call signal (20 kHz audio tone) the orange LED on its companion talk button will first flash and then light continually. The only exception is if button 4 has been set to the Call mode. (In this mode button 4 will allow call signals to be generated on talk channels 1, 2, and 3.) It will not light in response to a call signal being present on audio input channel 4.
MODEL 374A INTERCOM BELTPACK Model 374A is identified using the Identify command within Dante Controller or STcontroller all enabled talk channels will be forced to their disabled state. If the Global Kill Command method is enabled the Model 374A will respond to any such request and force all talk channels to their disabled state.
MODEL 374A INTERCOM BELTPACK Optimizing Network Performance For best Dante audio-over-Ethernet performance a network that supports VoIP Quality-of-service (QoS) capability is recommended. This can be implemented on virtually all contemporary managed Ethernet switches. There are even specialized switches that are optimized for entertainment-associated applications. Refer to the Audinate website (www.audinate.com) for details on optimizing networks for Dante applications.
MODEL 374A INTERCOM BELTPACK flash memory by way of a USB interface. The Model 374A implements a USB host function that directly supports connection of a USB flash drive. The Model 374A’s MCU updates its application firmware using a file named M374A.bin. The update process begins by preparing a USB flash drive. The flash drive doesn’t have to be empty (blank) but must be in the personal-computer-standard FAT32 format. Save the new application firmware file in the root directory with a name of M374A.bin.
MODEL 374A INTERCOM BELTPACK the channel 1 button’s LED and then observing the channel 2 button’s LED. Alternately, the STcontroller software application can be used to identify the application firmware version number. Whatever method you use, ensure that the desired version is present. 8. Once the update process has been completed reverse the steps and reattached the cover using the four machine screws.
MODEL 374A INTERCOM BELTPACK • The Model 374A offers a second method of activating the mic kill function. This allows a data signal, in additional to the Device ID command, to activate mic kill. • The STcontroller software application now offers the ability to configure the mic kill function, including allowing it to be disabled. • The Model 374A allows button 4 to be used as a call button function.
MODEL 374A INTERCOM BELTPACK Specifications Power Source: Power-over-Ethernet (PoE): class 1 (very low power, ≤3.84 watts) per IEEE® 802.
MODEL 374A INTERCOM BELTPACK Appendix A STcontroller default Model 374A configuration values: Microphone Input – Electret Power: Off Microphone Input – Gain: 42 dB Headphone Output – Channel 1 Input Routes to: Left Headphone Output – Channel 2 Input Routes to: Right Headphone Output – Channel 3 Input Routes to: Left Headphone Output – Channel 4 Input Routes to: Right Sidetone – Level: Medium Button Operation – Channels 1 through 4: Push to Talk/Tap to Latch System – Mic Kill: Global Kill Command Issue 3, A
