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Help debugging AVR related multi-channel upmix problem


Major Contributor
Forum Donor
Jan 23, 2020
AVR in question is a Denon X4400H

It's a 9.1(2 front height and 2 rear height) setup that I used to use for Auro-3D playback. Due to a recent move and just now recently getting set back up, it's been awhile(a year or so) since I've tried using one of the upmix algorithms on the AVR(almost always Auro-3D)

1. Stereo setting works fine and plays through the FR, FL and Subs properly
2. Any sort of upmix algorithm only plays through FR, FL and the two front height speakers. Center channel, both side surrounds, and both rear heights are silent. This is consistent amongst all upmix algorithms(Auro, Dolby, DTX, etc.).
3. Multi Channel Stereo Setting correctly plays through all 9 speakers

Manual Setting Config under the AVRs settings are attached

My thoughts so far in my attempts to debug the issue
1. The fact that all speakers play sound in the multi channel stereo setting means that everything is most likely properly connected
2. The fact that I'm able to select the Auro-3D setting at all means that the (silent) back height, center, and side surrounds channel speakers are being detected by the AVR
3. If I disconnect (for example) the rear height speakers, I lose the option to even select Auro-3D, which further confirms what I thought in #2
4. The fact that the front heights are being correctly upmixed means that the feature is working in some capacity. If the upmixer in the AVR were broken, I would expect the surround modes to not work at all.

Any ideas or avenues I should pursue in trying to debug this issue? Unfortunately, I don't have another 9.1 capable AVR. All suggestions are welcome.


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If you haven’t already factory reset. Then change your HDMI cable.

You didn’t mention your source, but it could also be that a wrong header bit is being generated in the stream
After more debugging it turns out to be the ATMOS4All implementation over the HDMI cable on the windows 11 machine I'm using as the source.

Not a surprise really, as a few years ago I tried to do some multichannel room correction with Mitch Barnett, but could never get ASIO4All to work without bugs.
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