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

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I’m running an LG C9 with a Panasonic UB820 Blu-ray player, Sonos Arc + Sub gen 3 + One SL surrounds. The lack of DTS support on the Arc has been frustrating for non Dolby encoded Blu-ray discs, so I have been eagerly awaiting the multichannel PCM update.

It’s finally arrived (thanks, Sonos!) and I tried playing a DTS encoded Blu-ray and… no dice. Still stereo PCM 2.0. Has anyone running a similar set-up managed to get 5.1 PCM output from the Arc?

The C9 supports eARC and multichannel PCM, I’m using 48gbps HDMI cables that support up to 8k60Hz, all of the devices are up to date, I have the C9 set to PCM with eArc enabled, DTS output set to PCM on the UB820… I’m really at a loss here. Any ideas or suggested settings?

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@Chetiya Glad you got it working with the Arcana. I experience the same video input drop on my Panasonic TV for a few seconds too. You’ll get used to it over time.


@Chetiya Glad you got it working with the Arcana. I experience the same video input drop on my Panasonic TV for a few seconds too. You’ll get used to it over time.

Thanks for confirming. Yeah it’s a minor gripe, doesn’t impact the actual viewing experience. 

I've got cases open with Panasonic and LG around this issue but only getting generic responses thus far. I’m not holding my breath!

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I wanted to share some new experiments. All of this is preliminary!!!!

I just received the hardware to make adjustments to the DR HDMI 4K EDID custom units. I went with both the Bluetooth module ($49) and a USB cable (only $10). At this point, I am all about the experimenting so caution continues to be thrown to the wind.


Reminder, I have the Panasonic 820, the LG C9 55” and the Sonos Arc + Sub + Surrounds (2). All units are on current firmware releases. Symptom: Inability to send multichannel sound from DTS tracks (converted at the Panasonic) through to the Arc. Dolby formats and 2.0 tracks all work fine. I want to retain Dolby Vision and HDR format compatibility for 4K discs.


With DR HDMI 4K in the signal pathway, I can fix the audio problem, but I lose Dolby Vision. With the HD Arcana, everything works fine although I am using the device in an odd format vs its intended use. 


My thesis is this: 

I would like to use the EDID output from the LG but edit it to fix whatever issue is causing it to not output MC PCM audio. I prefer to use the LG EDID because all other aspects seem to be working (video formats, color gamma, Dolby audio). 


Using the DR HDMI 4K, I copied the EDID from the LG to the SINK setting. I then transferred that file via the HDFury iOS app (via the bluetooth dongle) to my iPad. That was then moved to my PC (via cable) and imported into the Advantiv EEditGold program. I also saved the HD Full Audio EDID profile that produced the correct audio (but was missing the Dolby Vision ability) for comparison. 


Looking at the two files, I focused on the audio sections. I do not want to touch video because it works in the original profile.


Here I found two differences. They both seem to be necessary, but I need to keep playing to know how much has to match.

First, the audio formats on the LG EDID are missing the 1 bit audio. This is SACD so it seems odd this is needed, but I added it back in and adjusted the listed order to match the working EDID.

Second, and I believe at the heart of the matter, the LG EDID does NOT include the speaker table. This section tells the player which speaker locations are available for output. I added this block (see image) and enabled the same channels. 


I exported the new EDID block to a .BIN file and reversed the pathway back to the DR HDMI 4K, using a custom slot. 


Voila! This change enabled both desired states - at least with my limited testing. Dolby Vision working for those UHD discs. HDR for my 1 4k disc that only has that instead of Dolby Vision. Dolby Atmos still working all the way to the Arc. And LPCM 7.1 audio output (from 5.1 or 7.1 tracks) Upsampling from 1080 images to 4K working. 24 fps, 30 fps and 60 fps all working.


More to follow as I want to really nail down the minimal fixes to make this work. 

Again, for ease of use, the Arcana is the way to go. For those brave to follow this, it is possible to get there with a DR HDMI 4K and a likely a $10 USB cable (although I still need try that exact path). 


More testing tomorrow.


That’s fantastic work Laird! I think modifying the TVs EDID to allow it to support a legitimate format makes sense. No idea who is at fault here based on your findings, I’m not sure there are universal standards that aren’t being adhered to or if it’s a vendor by vendor implementation. 

Have you got a case open with LG and / or Panasonic where you can update them with your findings? 

Also, it might be helpful if you could upload the fixed EDID file somewhere, it would probably help people as they’d only need to copy it their Dr HDMI without having to do any editing. 

At this point I’m happy with my Arcana so probably won’t be doing this, although if I can’t find a buyer for my DR HDMI I may try it and sell the Arcana instead as it’s an in demand product. 

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Thanks, @Chetiya


I do plan to open a case although I know others on this thread have one going. But I am going to do so when I really can pinpoint the issue. My ideal is to find the absolute minimum number of bytes to change. 


In terms of uploading a file, I do plan to do that with caution. First, I need to remove my serial number. Second, I want to be sure I have figured it out reliably. Also, this will really only work for a C9 model TV. If someone wants to send me a CX EDID, I am happy to send back a few variants to try. Also, I think the EDID file also is aware of the screen size (55” in my case). So, that too might be a factor with using my EDID vs doing the editing. But anyway, I am happy to share for those willing to experiment. I make no warranties or guarantees!


Again, more to follow when I get back to playing around again. I am having fun with this and I am hopeful if I (or others) can truly figure out the problem, LG or Panasonic (or even Sonos) can adjust on their end.


My guess is that the issue is actually Panasonic’s. It may be that Panasonic’s routine to downsample DTS to multichannel PCM requires this mapping to know which channels to pass along and tag and which to fold into their output. This might be to better support Atmos and DTS X positional data in the decode. Again, this is my guess. So, when the Panasonic does not see this info, it moves to a safety mode of 2 channel, since every modern device supports that. As reported on this thread, other players (LG, Sony, Oppo) do not have this issue - they correctly output MC PCM and there is no reason to believe the EDID passed by the LG to those is any different than what the Panasonic sees or I extracted.


I did end up activating additional “supported” frequencies in the EDID audio section, so I want to play around with that and see if changing those alone (without adding the Speaker block) might be the true root of the issue.


(Also, the 1 bit Audio - SACD is definitely not required. I eliminated that last night and everything still works. This is as expected.)



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Ok, I’ve played around a bunch more, and I believe the only issue is that the C9 EDID is missing the speaker data. I tried to add various audio format and sound frequencies which are different between the LG EDID and the one that worked for audio but not Dolby Vision. In the file linked below, the only changes are:

  1. I added the missing speaker data (see screenshot below)
  2. I changed the serial number from my unit to something else (same number of digits). (I doubt this matters to anything.)


This is the file for a C9 55 TV. It may work for other C9 series TVs. I am let sure about B9 or G9. I certainly do not believe it will work for the CX series. (However, I am happy to edit a file for someone if they wish me to try.)


Disclaimer: While I am technical in nature and have been involved in computers and consumer electronics for years, this whole area is new to me. I cannot take any responsibility for the use of this file. I provide it merely for example and experimentation purposed. I do not work for LG, Sonos or Panasonic.


Ok, here is the link: https://www.dropbox.com/s/2986ilhxe5opkus/LG%20C9%2055%20EDID%20Sonos%20Arc%20Speaker%20Data.zip?dl=0


I have a few more experiments to run, but I think I have enough to flag Panasonic that they are failing on this EDID issue and LG for not passing this information from the Sonos.




@Laird M Malamed Thanks for narrowing down what seems to be the issue between the Panasonic player and the LG TVs with the missing speaker data. I don’t think I spent the time to notice the speaker data was different/missing when I was playing around with all this. Unfortunately I’m not able to play around and test this out with my CX setup at the moment, but maybe I’ll be able to confirm the CX has the same problem in a couple weeks or so and also confirm that I’ll be able to fix it by updating the LG output EDID with the missing speaker data (instead of my previous method of taking the existing Dr HDMI profile and adding the missing Dolby Vision info).

Hopefully with this level of detail on the problem, either Panasonic or LG will provide some kind of fix.

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I found an error in my shard EDID file above. It is an interesting find because it makes me think that Sonos may be the source of the issues after all. Or how the Sonos and LG talk to one another. 


The error has to do with audio frequency. (Specifically, I have a number of Blu-ray Audio discs. These discs basically have one image - a menu of sorts - and the rest of the disc is Hi-res audio. I like the format (mostly for classical and opera) because I can see the track easily but am not distracted by the image of a conducted concert.)


Today, I happened to put in a disc with DTS-MA 2.0 channel at 192 kHz sample rate. (Confirmed in the status menu that this frequency. I think DTS-MA is somewhat of a container format.) Guess what? The audio could not be rendered by the Sonos. That is not a surprise though - the Sonos is limited to 48 kHz. What surprised me is that even with the Panasonic set to decode DTS to PCM, it did so at the 192 kHz native rate. I looked back at the stock LG EDID, and indeed it shows that 192 kHz (and 96 kHz for that matter) as a supported audio format - which indeed it is for the LG’s internal speakers and playback. I adjusted my EDID on my HDFury DR HDMI 4K and removed the LPCM frequencies  above 48. Presto, the Panasonic correctly output at 48K and the audio played.


Now, what is more interesting is that all of this was with HDMI ARC “Passthrough” audio selected. This is needed to support Dolby Atmos as True HD all the way to the Sonos. When I changed the setting to “Auto” and used the stock LG EDID, the Panasonic output 192 kHz but the Sonos could play it. Why? Because the LG must have been re-encoding it to 48 kHz. Hence, the LG “knows” that the Sonos cannot support the higher frequency - or that is my guess. So, why does the Sonos not broadcast to the LG the speaker configuration data? And why does the LG not pass that along?


So, for those trying this themselves, the needed changes to the EDID are:

  1. Add the speaker configuration data
  2. Edit the LPCM formats and remove the 192 and 96 kHz options 
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I’m a bit of a layman with all this and not sure I understood all of the posts.

To clarify, will those two steps fix the LPCM issue for this setup, without needing an additional switcher?

I’m still hesitant to pay more money for something I should have, so looking for a solution without added gizmos.

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Interesting. I wonder if that’s a bug from when they rolled out LPCM support?

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I’m a bit of a layman with all this and not sure I understood all of the posts.

To clarify, will those two steps fix the LPCM issue for this setup, without needing an additional switcher?

I’m still hesitant to pay more money for something I should have, so looking for a solution without added gizmos.

Yes, that is my preliminary finding. Also, I suspect that the HDFury Arcana will NOT work if the source audio is decoded 192 or 96 kHz. However, with the DR HDMI 4K, the result looks doable. I am using my fix now and playing back 192 kHz files correctly as downsampled 48K.


As far as I can tell (and others on this thread), the only way to get decoded DTS in multichannel PCM is to use an intermediary device or swap out the Panasonic for a different player. It really depends on how many discs you have and in which formats. You could also rip discs and decode the DTS at that time. Of course, that is a whole other source of pain.


I was just looking at old LG C9 threads at their site, and this was spotted back in 2019. LG said they had fixed MC LPCM then and people reported it working, at least from PlayStations and Xbox’s.


I want to do a few more tests this weekend using the LG 90 UHD player to confirm that does work as expected. (The issue with that player is you cannot chose to decode DTS without doing the same to Dolby Atmos too.) After I have that info, I will chase LG and Sonos on this issue.



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Interesting. I wonder if that’s a bug from when they rolled out LPCM support?

That is what I am wondering too. Or could be LG’s. They show 8 channel support, but not which configurations those go to in the EDID.

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Thanks @Laird M Malamed for your work on this!

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Keep going gents, once we have concrete evidence which manufacturer is to blaim i will be read to bombard them with your findings :D


At the minute all three manufactureres blame the other, however i didn’t think Sonos were to blaim at all initally!

So here’s my experience. I have the LG B9(same as C9/E9 from an Earc standpoint), Sonos Arc + One sl surrounds. I run 4k disc on my Sony ubp-x700 player. For the longest time I couldn’t play any DTS disks in anything other than stereo 2.0. I haven't had a chance to test the LPCM update for the Arc until last night. With my LG B9 set to “passthrough” instead of “Auto” under the HDMI ARC setting I put Inception 4k(DTS-HD Master Audio 5.1) in the x700 player, changed the “Digital Audio Output” to PCM and Hallelujah. Sonos app reads Multichannel PCM 5.1. The sound is by far better than that stereo 2.0 crap. I am one happy camper. I should also note 2 things. (1) I tried this with the Inception standard blu-ray on my ps4(slim) with it set to LPCM and the result was same. Multichannel PCM 5.1. (2) The tv HAS to be set to “Passthrough”. When switching back to “auto” I DO NOT get Multichannel PCM 5.1, only stereo 2.0. 


I'm gonna test Bad Boys for Life 4k as it has a DTS-HD Master Audio 7.1 to see about any possible downmixing issue with the Arc update. 

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@Sonosrookie20 unfortunately, there are still indeed issues when down-mixing LPCM from 7.1 to 5.1.

That being said, has anyone confirmed whether Dolby TrueHD down-mixing from 7.1 to 5.1 experiences the same issue? I know the CEO/tech team has acknowledged the LPCM issue on twitter and reddit, but not sure if it affects Dolby content as well.



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@jkossis I tested a Dolby TrueHD 7.1.2 test tones video from my Dolby Atmos demo Blu-ray on my 5.1.2 Arc/Sub/Play:1s setup. The test tones for the left and right side surround channels played perfectly clear out of my Play:1 rear surround speakers indicating that the Arc will take a 7.1 track and mix the two side surround channels into the two rear surround channels. 

I plan on testing the same with a DTS demo disc next week.

Perhaps the point has been made above but just to reiterate:

  1. Using HDFury to direct LPCM audio from a DTS 4k audio stream running in a blu-ray player into HDMI port direct of LG CX or bypassing LG CX to Sonos ARC directly if it is a DTS 7.1 audio stream turns into LPCM 7.1 (from Blu-ray player)
  2. This runs into the issue Sonos arc has which has still not been fixed of downsizing being wrong for LPCM 7.1 to surround 5.1 setup.

there is no issue for blu-ray disks supporting DTS 5.1






Hey guys, can anyone confirm that the Arcana doesn’t have the Dolby Vision issue?


I can 100% confirm that the Arcana works - you just need to set the device to pass the audio to the HDMI Out port and you do not use the eARC output port at all. You use the device just as a passthrough, similar to the intent of the DR HDMI 4K. This is my set up now and has been stable for weeks.


I can also confirm I am running into the Dolby Vision issue with the HDMI DR 4K. So, in my rushed eval on Monday, I missed this was not working with the built in EDID. I see now that the HDFury site has different EDIDs listed for the banks than what is on the sticker on the physical device. I have more to check on this and to get an EDID editor going for my personal interest.


And finally, I have chatted briefly on the HDFury Discord server with them. They are very fast and you can scroll through a ton of old chats too which can be helpful.


The Arcana only solves the handshake issue between UB820 and LG Cx to get UB820 to output LPCM for DTS mastered disks. As others have pointed out Sony blu ray player doesn’t have the handshake issue but regardless we still run into the following problem:

if it is LPCM 7.1 output ( DTS Mastered 7.1 streams) Sonos arc still has an unresolved bug after LPCM update that it doesn’t downmix properly from 7.1 to 5.1. @GuitarSuperstar @iBoyley @Laird M Malamed 


So if you have UB820 and LG CX, you need Arcana and Sonos arc firmware update. If you have Sony blu-ray player and a TV capable of passing LPCM you need Sonos arc firmware update. If you have either blu-ray player and a Samsung 2020 TV or projector LSP9T as I do which cannot pass LPCM, you need Samsung firmware update and Sonos firmware update.




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@madhav Next week, I’ll be receiving a DTS demo Blu-ray disc that includes a 7.1 DTS test tones video. I’m very curious to see how the Arc handles the 7.1 PCM audio my Panasonic UHD player will send it.


I just played Spectre 4K blu-ray on Sony Blu-ray player through LG CX to Sonos arc / 2x sub / 2 One SLs
The Blu-Ray outputs LPCM 7.1 (PCM conversion of DTS 7.1 audio stream) it is reported as 7.1 by Sonos App correctly.

The dialogue was fine, and there was surround from rears but it seemed to be lacking to my ear but I don’t have definitive evidence of mixing problem. The known Sonos bug is 2 surrounds in 7.1 are output from rears and what should be in rears is missing and not mixed in as I understand it.

@iBoyley If this turns out to be the case then HDFury (for those with Panasonic Blu-ray is only solving half the problem). Sonos have been working on a firmware fix for months now with no release. We should find out from CEO when that is coming. 





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@madhav That’s why I am interested to see how test tones from the left and right side surround channels and the left and right rear channels will play out of my two Play:1s. If all four surround channels play the test tones clearly out of my two rear speakers, I would assume that the Arc is downmixing the four surround channels correctly.

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I wanted to report my latest findings - alas nothing that creates a fix without the DR HDMI 4K. And based on other recent threads, that may only solving part of the problem (7.1 not rendering correctly on the Sonos Arc + surrounds). However, to the issue of even getting the Panasonic to output multichannel at all, this is what I have to report.


I have filed a ticket with Panasonic on this issue, giving them extensive notes and links to this thread and others which report the issue. I have noted that other players are correctly outputting MC PCM audio with the LG C9/CX and Sonos Arc combo. That was filed today, and I do not expect an answer soon. I specifically asked that the email be passed to their audio engineering team as a customer support rep will not be versed in this area.


My main experiment this weekend has been to use a LG 90 UHD player as source. Directly connected to the LG, and with the LG set to decode the Blu-ray audio tracks, 5.1 audio is received by the Sonos from both DTS and Dolby tracks. Thus, the video and audio portions of our systems works. This has been widely reported as working, but I wanted to confirm with my set up that it was the case.

Further, I was curious to look at the EDID file with this set up - in some way did the LG player + LG TV somehow communicate better since all in the same brand. The answer is no. The EDID file provided by the TV to the LG 90 player is the exact same data as it shows to the Panasonic. This was absolutely my expectation, but I figured better safe than sorry.


I did a few other setting attempts just to see what happened. For example, I disconnected the Sonos and used the TV speakers. In general mode, I enabled Dolby surround for the internal speakers which creates a fake support mode. The Panasonic still refused to give out more than 2.0 PCM. (Note, with my C9, I could actually feed it DTS audio, but that is not the end goal here, so the point is moot. The CX would not support DTS in any regard.)


Basically, as far as I can tell, if you want full functionality from the Panasonic UMB820, you need to use a device that allows modification of the EDID file to correctly advertise Speaker data.


If you want to switch UHD players, alas all of them come with downsides:

LG - Decoded audio is all or nothing - DTS and Dolby cannot be selected individually. No upscaled 4K images from 1080P discs. 

Sony - Dolby Vision support requires toggling a setting

PlayStation or Xbox - I believe this can be set up to work for all discs and decode everything properly (plus you get a video game machine). However, unless you buy a remote, you have to use the game controller for control. The LG remote might work to a limited extent too.

Pioneer - not sure on this. Have not seen many threads.

Oppo - I think this works in all formats, but the unit is only available used and at high prices

Rip all media to video files and playback off USB/HD/Network - this works but of course is very manual to rip your library of discs!


I will report back what I hear from Panasonic. Based on previous threads, I suspect I will not get far. 


I would love to hear that a Sonos rep is aware of this thread and perhaps can look at this too - maybe the Sonos can tell the LG what speakers it has? I am very unclear how EDID data works from soundbars. I tried to see if I could hook up the Sonos to the DR HDMI 4K and capture it’s file, but this did not work at all.






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Hey people. In regard to the Panasonic 4K bluray players I’m going to suggest Panasonic have still been trying to improve it.


Yesterday I popped in Divergent to watch which has a DTS-X track. To my surprise I got quite a good surround experience compared to previous viewings. It was noticeable because the sequels have Atmos tracks and gave a much better experience with my Playbase setup. Bit weird because the specs for the 420 at least say no DTS-X decoding, only bitstream.


I always thought changing the Down mix setting to surround encoded didn’t do much of anything. 

I had changed the DTS down mix setting to PCM after reading all these threads but swapping it back still gave me pretty good surround.


Other DTS-HD based tracks don’t seem to give as much obvious improvement but after a quick little try I think Inception might give me decent surround if I bump up the volume on the surrounds. The front action from my Playbase seemed better. Will watch it tonight and see. Will also try to pick up another DTS-X track to see how a different one goes.


Anyway, this just to say hopefully everything will get sorted at some stage. Chin up.


I still expect to get an Arc at some stage though. 




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^^^^^ Goodness I am glad I put Divergent with its DTS-X track on again. My quick test of a DTS-HD had me thinking I just needed to bump up the surrounds a bit to get a decent surround mix out of them and that proved to be true.


I was particularly happy to get the music score for 2001 also coming from the surrounds. Stereo from the front always felt a bit lacking after being to the surrounds being used for music playback.


+5 on the surrounds seems about right.

Not much of a pain to do it for the few DTS-HD discs I have. Fortunately I don't have any legacy Blurays.