Dolby Atmos Test Tones Video - LFE Channel

  • 31 July 2023
  • 3 replies
  • 795 views

Userlevel 7

I need some help figuring this out.

 

My setup:

Arc + Sub (Gen 3) + Era 300s

TV: Panasonic plasma (2013) with HDMI ARC

Because of the older TV, I use an HDFury Arcana with a Panasonic UB820 UHD player, Apple TV 4K, and Roku Ultra connected to it with a ROOFULL HDMI switch.

 

I have a Dolby Atmos demo Blu-ray disc that includes a 7.1.4 Test Tones video both in Dolby TrueHD and Dolby Digital Plus. When the video gets to the LFE channel test, the bass tone plays from the Sub like it should, but the pink noise test tones also play from the Arc’s drivers at the same time. The surround speakers remain silent. The combination of tones playing from both the Sub and Arc is much louder compared to when the individual pink noise tones are played through the other channels during the rest of the test video. I get the same result with both the Dolby TrueHD and Dolby Digital Plus settings on the disc.

 

When I play the same 7.1.4 Dolby Atmos test tones video (MP4 file with Dolby Digital Plus audio) from my iPhone (from Safari) via AirPlay to the Apple TV or Roku Ultra, the LFE channel only plays from the Sub while the Arc remains silent. This seems like how the LFE test tone is supposed to play rather than the result I get with the Blu-ray disc above.

 

When I play a DTS-HD Master Audio 7.1 Sound Check video on Blu-ray disc, the LFE channel also plays only from the Sub while the Arc remains silent.

 

So what exactly is happening here? When I play movies on Blu-ray disc in Dolby Atmos, everything seems to sound fine. Why is the pink noise playing on the Arc during the LFE channel test on the Dolby Atmos test tones Blu-ray disc?

 

For reference, this is the test tones video I am using:

https://download.dolby.com/us/en/test-tones/dolby-test-tones_7_1_4.mp4


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3 replies

Userlevel 7

I would assume the Test Disc you are using was designed for a system consisting of multiple speakers (separates) such as:

  • Left Front
  • Center Front 
  • Right Front
  • Sub
  • Left Surround 
  • Right Surround

The above is the basic configuration that does not include Left/Right side speakers and/or overheads. My point being is that the Arc combines the L/C/R channels which you can’t control as separates. Also the test disc is probably looking for additional speakers to send a tone other than the sub and two rears.

IMO (assuming you have or can borrow an iOS device) you are better off using TruePlay to adjust the sound parameters of the Arc, sub and surrounds to your space. 

Userlevel 7

I would assume the Test Disc you are using was designed for a system consisting of multiple speakers (separates) such as:

  • Left Front
  • Center Front 
  • Right Front
  • Sub
  • Left Surround 
  • Right Surround

The above is the basic configuration that does not include Left/Right side speakers and/or overheads. My point being is that the Arc combines the L/C/R channels which you can’t control as separates. Also the test disc is probably looking for additional speakers to send a tone other than the sub and two rears.

If this is the case, why do the left front, right front, and center channel test tones play separately out of the proper drivers on the Arc? And how would this explain the same test tones video playing correctly via AirPlay to the Apple TV or Roku Ultra?

Userlevel 4
Badge +3

The test tones played from a Nvidia Shield are also coming from the correct speakers. I’m wondering if the BD Player has some kind of bass boost function or so that will send the LFE also to the front channels. That or a function similar would be the only explanation I could think of (besides a defect being it software or hardware of course).