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Atlona HDMI Multi-Channel to Two-Channel Audio Converter

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Model Number: AT-HD-M2C

The Atlona AT-HD-M2C is an audio converter used to extract multi-channel Dolby® and DTS® surround sound signals from HDMI sources for conversion to stereo analog or digital signals in residential environments. In multi-zone applications where multi-channel audio is distributed from an HDMI source, installers need an easy solution to extract stereo audio for two-channel zones while maintaining a surround sound experience for home theater, multi-channel zones.


  •   Overview
  •   Specifications
  •   Documentation
  •   Video
  •   FAQ
  •   Firmware

The AT-HD-M2C is integrated between an HDMI matrix switcher and a display. Multi-channel audio content up to Dolby TrueHD and DTS-HD Master Audio™ from Blu-ray Disc players, set-top boxes and game consoles is down-mixed for the two-channel zone. Audio signals are made available simultaneously on stereo RCA connectors as well as digital optical and coaxial ports. The HDMI output passes high resolution video signals up to 1080p, 1920x1200 and 3D to the display.

Comprehensive Audio Signal Format Conversion and Compatibility

In whole-home systems which include both surround sound rooms as well as rooms with conventional stereo audio, it’s not unusual for an HDMI source to be forced to provide a down-mixed, stereo signal due to the needs of the two-channel room, preventing multi-channel rooms from receiving the best possible signal. The AT-HD-M2C overcomes this limitation without adding system complexity or increasing costs while providing a number of features designed to simplify installation.

A front panel HDMI connector accepts all Dolby and DTS codecs from Blu-ray Disc players, set-top boxes, and game consoles. Data is sent back to the source to preserve the multi-channel signal for the surround sound zones while the AT-HD-M2C extracts two-channel audio. The front panel of the compact metal enclosure also includes LEDs for power and incoming signal format indication. A front panel USB connection allows for easy firmware updates.

The back panel provides simultaneous two-channel output on analog RCA connectors and digital optical and coaxial ports. Included on the back panel is an HDMI connector for routing high definition video to displays up to 1080p. Incoming multi-channel audio is down-mixed to two-channel audio for re-embedding onto the HDMI output. A free firmware update is available to preserve the original multi-channel audio on the HDMI signal’s embedded audio stream.

The AT-HD-M2C is HDCP compliant and is designed to integrate seamlessly with all Atlona HDMI switchers, matrix switchers, and the Atlona HDTX/HDRX family of HDMI Extenders as well as third-party HDMI matrix switchers.

The AT-HD-M2C is truly unique in the residential market offering plug and play setup, a compact enclosure, status indication, multiple audio outputs and compatibility with high definition multi-channel formats up to Dolby TrueHD and DTS-HD Master Audio.


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Sharing sources across mixed two-channel and multi-channel zones results in a degraded home theater audio experience. The multichannel zone, a high-end 5.1 home theater for example, is forced to accept the compatible low performance audio stream required for a two channel zone such as a flat panel TV.

The AT-HD-M2C solves this dilemma by allowing the distribution of full audio to each zone then seamlessly down-mixing from sources such as lossless HD audio for two-channel zones. No audio compromises required, enjoy the best HD audio for your home theater and simultaneously enjoy two channel audio in the kitchen or bedroom.

Atlona Advantage

  • Digital coaxial and optical ports plus analog stereo audio outputs for connection to legacy AVRs and systems without HDMI support
  • Reduces system complexity and costs by eliminating the need for separate, dedicated sources for each zone
  • 7.1 and 5.1 multi-channel to two-channel down-mixing and simultaneous audio conversion to all outputs
  • Comprehensive audio format signal compatibility: PCM, Dolby® Digital, Dolby® Digital Plus, Dolby® TrueHD, DTS Digital Surround™ and DTS-HD Master Audio™
  • Atlona’s Intelligent EDID Management guarantees the best audio performance and video signal pass-through
  • Plug and Play functionality eliminates the need for any setup, programming or configuration
  • Fully HDCP compliant allowing any protected content to be transmitted
  • Front panel LEDs for power and incoming audio signal format indication
  • Front panel mini USB port for easy firmware updates
  • CEC pass through support

Free Optional Upgrade: HD-M2C Multi-Channel HDMI Output

Firmware version 2.1.0 modifies the standard HD-M2C HDMI output behavior from two-channel down-mix to multi-channel pass-through preserving the original embedded audio signal. A 7.1 DTS HD-Master Audio stream from a Blu-Ray player will simply pass-through the HD-M2C completely intact. This allows a multi-channel signal to be transmitted to an AVR and a two-channel analog signal to a multi-zone audio amplifier simultaneously.


  Video 480i@60Hz, 480p@59.94/60Hz, 576i@50Hz, 576p@50Hz, 720p@50/59.94/60Hz, 1080i@50/59.94/60Hz, 1080p@23.98/24/25/29.97/30/50/59.94/60Hz
  VESA 800x600@60/75Hz, 1024x768@60/75Hz, 1280x768@60/75Hz, 1280x800@60Hz, 1280x1024@60/75Hz, 1366x768@60Hz, 1440x900@60/75Hz, 1440x1050@60Hz, 1600x900@60Hz, 1600x1200@60Hz, 1680x1050@60Hz, 1920x1200@60Hz
  Colorspace RGB, YCbCr 4:4:4, YCbCr 4:2:2
  Color depth 8-bit, 10-bit, 12-bit
  Formats PCM 2Ch, LPCM 5.1, LPCM 7.1, Dolby Digital, DTS 5.1, Dolby Digital Plus, Dolby TrueHD, DTS-HD Master Audio
  Sample Rate 44.1kHz, 48kHz, 96kHz, 192kHz
  Total Harmonic Distortion 0.0025% (-92dB, sample frequency: 48kHz)
  Signal/Noise Ratio 106dB
  Gain 0
  Frequency Range 20Hz to 20kHz
  HDMI up to 10 meters up to 30 feet
  Bandwidth 6.75 Gbps
  CEC Pass through
  HDCP Compliant
  Operating 0°C to 40°C 32°F to 104°F
  Storage -20°C to 60°C -4°F to 140°F
  Humidity 20 to 90% non-condensing
  Consumption 2.6W
  Supply Input: AC100~240V 50/60Hz
Output: DC 5V/2.6A
  H x W x D 43.66 x 138.11 x 105.70 (mm) 1.72 x 5.44 x 4.16 (inch)
  Device 0.26kg 0.57lbs
  Shipping 0.67kg 1.48lbs
  Power Supply CE, FCC, cULus


  Features 3D, 1080p, 1920x1200, Dolby TrueHD, DTS-HD Master Audio
  Features 3D, 1080p, 1920x1200, PCM 2Ch @ 48kHz (up to Dolby TrueHD/DTS-HD Master Audio using firmware V2.1.0)
  Optical OUT
  Audio PCM 2Ch @ 48kHz
  Coaxial OUT
  Audio PCM 2Ch @ 48kHz
  Analog OUT
  Audio 2Ch (L/R) @ 48kHz
  Mini USB
  Use Firmware updating

Package Contents

QTY   Item
1   AT-HD-M2C
1   Locking 5V DC Adaptor
1   User manual

 Declaration of

 CAD files

AT-HD-M2C features
  Sometimes there is an audio delay when changing channels on my cable/satellite set top box, why is that?
  This audio delay occurs when there is an audio format change. An example would be if one channel was broadcasting a 2CH. PCM signal and was switched to another channel that is broadcasting a Dolby Digital signal. There will be a slight 1-2 second delay in audio to prevent any kind of audio distortion or popping.

  Does the AT-HD-M2C let me play Multi Channel through the HDMI and stereo through the other outputs?
  It depends on the firmware you have on your AT-HD-M2C. Only FW 2.1.0 and above support Multi Channel via HDMI output. See "Firmware Updates" tab to download the latest firmware.

  Can I use extenders to go into our come out of the AT-HD-M2C?
  It is possible to use extenders with this unit, we recommend using any HDBaseT extenders such as our AT-HD(TX/RX) family.

  Can the AT-HD-M2C be left on constantly?
  The AT-HD-M2C does not need to be powered off and can be permanently left on.

AT-HD-M2C Firmware

Download Firmware version 2.0.7 Download Firmware version 2.1.0
File Size 181 KB File Size 181 KB
Date 10.07.14 Date 06.27.14
Update 2.0.7 Includes:
      • Fixed compatibility with Dune HD and other HD products
Update 2.1.0 Includes
      • Modifies HDMI output behavior to multi-channel audio