LG C9 + Arc + UB820 / Multichannel PCM for DTS Blu-Ray discs

Thank you @Silverthorn for explaining. So basically, there is no indication on the Sonos app as “confirmation” (like it is when you e.g. hear Dolby variants, etc.), you can only confirm by closely listening. That would also mean changing back and forth between “Downmix” → “Surround encoded” and “Downmix” → “Stereo” should make a difference when listening, correct? I will give this a try. Just out of curiosity: did you find this out yourself or was this documented somewhere?

To give you a little broader background on how I initially tried to achieve what I wanted to achieve: next to my Panasonic Blu-ray, I have a Media PC (an Intel NUC) which is running Kodi mediacenter. This streams my digital movies from a NAS drive in my home network. I have a lot of digital movies with DTS sound too and I only recently found out that Kodi is able to transform multichannel audio (like DTS) to AC3 in 5.1 sound - so despite these DTS encoded movies, I can watch them via my LG BX TV (no DTS passthrough) in Dolby Multichannel 5.1 sound, transcoded by Kodi and outputted on my Sonos Beam 2.

The discussion I had on this can be found here: https://forum.kodi.tv/showthread.php?tid=367120

Long story short: I was somehow hoping to solve this the same way with “tweaking” my settings on the Panasonic Blu-ray and have my DTS Blu-ray discs played on my Sonos Beam 2 with “Multichannel 5.1” sound. I don’t care if it’s not “native” DTS - anything better than this crap Stereo PCM sound would be considered a success for me.

As a lot of other users, I did not pay enough attention to DTS-passthrough capabilities when I initially bought this LG TV in 2021. I only added the Sonos Beam 2 in 2022 and the Panasonic Blu-ray in 2023.

Anything else with Dolby sounds absolutely great on the Beam 2, regardless if I play the source on Kodi with digital media or via Blu-ray discs on the Panasonic. It’s just that DTS on my discs are giving me a headache that I couldn’t figure out on my setup yet...😩

Thinking out loud - if people are getting multi channel LPCM using Switch/PS4 etc with the C9 and Arc, then doesn’t that mean the issue must be with UB820 or the type of PCM the UN820 is sending out?

If I get the chance I will try this using a Samsung tv in the other room. I think it has ARC (not eARC) but hoping I’ll at least be able to see if UB820 is sending 5.1 PCM or if it’s still 2.0

Wouldn't be surprised. Everyone is looking to streaming which has pretty much become Dolby ? Sony is still  supporting DTS I believe.

If the UB820 is set to convert the DTS audio to PCM before it passes through the LG to the Arc, then the DTS incompatibility problem with the LG TV shouldn’t be an issue.

@Parkerdip Secondary Audio needs to be turned OFF when watching Dolby Atmos-encoded discs.

No as I mentioned I only noticed it when I replayed Divergent and noticed I was getting a decent surround experience. It was a DTS-X track and for some reason they seem to get bit more volume in the surrounds so it was quite noticeable.

I’m not sure but I think they added support for LPCM around that time so they might have added support for this as well. If I remember people were surprised LPCM wasn’t already supported and agitated for it? Someone else might remember more. 

The UB820 can send 5.1/7.1 channel PCM. It’s more than likely a handshake issue with the LG and UB820 or the LG and the Arc.

still no difference when changing either of the above. I think I’m just going to wait until the new LG FW comes out now as there is no reason why this shouldn’t be working

i just played the disk on my Xbox series x and can get whatever audio format I want (was even displaying Atmos at one point on my “about my system” screen which I thought was a bit odd)

You've probably already checked this 100 times… but just in case something was reset at some point:

TV set to:  Sound = Passthrough 

820 Digital Audio Output set to: Bitstream, Bitstream, Off 

Thanks for the thread.

I have a Panasonic UB820 on order from Best Buy (took advantage of the $100 off sale). Meanwhile, I have been using a LG UBK90 4k Blu-ray player with the Arc (+Sub + 2 SLs) and LG C9 55”. I can confirm that I can get multichannel PCM from a DTS track through the TV to the Arc by converting it at the Blu-Ray player. I have 18 gbps + ethernet cables connecting all components.

Sharing my set up to see if we can isolate the problem with the UB820. See below for ideas on testing for those with the three components in this thread. 

My current set up:

LG UBK90 4k player via HDMI to Input 3 of LG C9 55”. Both are on the latest firmware

Sonos Arc + Sub + SL (x2) bought in November 2020. Also on latest firmware.

TV settings:

Audio out: HDMI ARC

eARC enabled

Passthrough Audio

From the UBK90 for DTS-MA discs

Audio Output set to PCM. I think that is the only setting that impacts this.

When I play a DTS 1.0 (mono) disc, I get PCM 3 Channel reported on the Arc. (Presumably, the converter in the 4k player is sending silence to the L&R and passing the 1.0 channel to the center.)

With DTS 2.0, I get PCM 2.0

With DTS 5.0, I get PCM 5.0

With DTS 5.1, I get PCM 5.1

I do not have a DTS X disc to try, so nothing to report there.

If I leave the UBK90 in Bitstream mode, I get no audio at all. (This makes sense since the Sonos at the end of the chain cannot process DTS. I thought if the TV were in Auto HDMI Arc out, it might handle decoding and re-encoding, but no luck on that.)

If I want to play a Dolby Atmos track from a 4K disc, then I have to put the UBK40 back into Bitstream mode. There is no separate option for Dolby and DTS handling on this player as there is on the Panasonic higher end models. If I don’t do this, I get a PCM 2.0 track which is probably the UBK taking the back up 2.0 channel that I think is in most Atmos mixes. Not sure. So, the annoyance is having to remember to swap settings on the UBK if I change discs. Dolby Digital 5.1 will decoded to PCM if in that mode or will pass through to the Sonos if I am in bitstream mode.

However, everything else is working as I would expect - I can get all the channels delivered to the Sonos from the source media. They sound correct to my ears during playback. So, if there is a handshake issue with the Panasonic, it is not a general failure - it is a specific one.

I can also report that AppleTV and my Tivo are all producing the right amount of audio as I would expect on the Sonos Arc via the LG C9. Atmos works and everything else is correct in terms of channels.

Back to the question of this thread and wondering if this configuration has been tested:

Using the Audio only HDMI output, directly connect the Panasonic to the Sonos. Use the first HDMI for the video to the LG C9. From there, adjust the output settings on on the Panasonic for DTS to mix down and for Dolby to passthrough to the 2nd HDMI port. TV can be in TV speaker mode (and should not get any audio anyway). 

I know this is not a good end state (since there would be no way to easily include other components), but it would at least determine if the Arc and Panasonic can hand off the multichannel PCM audio correctly. This may still mean that the LG or the Panasonic is at fault for the handshake error, but at least it would eliminate the Sonos.

I will try this if no one else gets a chance to. (My Panasonic is due in a week.)

Laird

Trap for young players (and some not so young): Make sure the firmware update for your devices has been done. The newly-updated Sonos iOS app doesn’t warn you if your speakers are not up to date. 
 

I had to turn eARC off for it to work for me.

(Panasonic UB820 —> LG C9 —> Arc)

Ok cool. Glad you were able to check that. Here’s hoping some sort of update comes along from LG. 

I did realize that Psycho 4K has a DTS:X 5.1 new mix (in addition to the now included mono mix), and I have the replacement disc on hand. On the set up described above with the LG player, I can report that with the LG in PCM mode, it passes a multichannel 7.1 to the Sonos (although I think it is only 5.1). 

I tried connecting the arc directly to the audio out HDMI terminal on the UB820 and the arc just kept flashing orange and white trying to establish a connection 

The Sonos app reported no audio at all