Yes, this setup should give you multichannel PCM 5.1 audio from DTS-encoded discs because the LG C1 is equipped with HDMI eARC. Just be sure to allow the Blu-ray player to convert DTS to PCM and allow your TV to pass through the audio through eARC to the Sonos Arc.

I still get 2.0 stereo……..connected to eArc I have changed the pass through on the tv and it goes silent. I watch lots of DTS movies on blu ray so perhaps I need to return my ARC for a Vizio Elevate.

What are the audio settings on the UHD player set to?

There are 3 options…….auto, PCM-Multi CH, and DTS-re-encode. I have tried all three and nothing changes……..do I need to change  I have read that the LG TV does not have DTS pass through and the Sonos Arc of course does not support DTS. So…...it appears I will be sadly returning the ARC for the Elevate. Someone suggested a HD Fury Arcana or an X box x….my god I do not game so what is the point to send hundreds of more dollars.

Try these settings:
 

UHD Settings

Digital Output - PCM

Sampling Frequency - 96 kHz

DRC - Off

HDMI Audio Setting - Auto

DTS Neo:6 - Off

TV Settings

Select HDMI Input Audio Format - Bitstream

Digital Sound Output - Auto

eARC Support - On

And be sure your TV has the latest firmware installed.

Thanks so much…..I will try this ASAP…..I am currently on the phone with Sonos to see if they have some resolution. I greatly appreciate all of your wonderful help. I will let you know. Thanks again.

Just  got off the phone with Sonos. They told me they could be of no help for my problem. Getting very irritated with Sonos. Anyway, I just changed the settings and still just stereo. I could not find the setting for the TV for Digital sound output…..just HDMI ARC device so left it there. All the others changed and still just stereo. Oh well…………..

What is your opinion of the Vizio Elevate?

Digital Sound Output should be under Advanced Settings:

Be sure the Arc is connected to the HDMI 2 port.

I would try each of these four combination of settings:
 

Select HDMI Input Audio Format (HDMI 2) - Bitstream

Digital Sound Output - Auto

eARC Support - On

Select HDMI Input Audio Format (HDMI 2) - Bitstream

Digital Sound Output - Pass Through

eARC Support - On

Select HDMI Input Audio Format (HDMI 2) - PCM

Digital Sound Output - Auto

eARC Support - On

Select HDMI Input Audio Format (HDMI 2) - PCM

Digital Sound Output - Pass Through

eARC Support - On

OK I will work on this today and tomorrow. FYI The ARC is connected to the HDMI 2 eARc port. Oh and just in case any of these work will I have to make this adjustment every time I view a DTS disc or will this be ok for Atmos discs too? Also, what about streaming with just the tv will I have to go back in and reset to prior settings? Thanks so much greatly appreciated.

It depends on which settings work (if any). At the very least you will have to adjust the Digital Output setting on the UHD player from PCM to Auto when playing a Dolby TrueHD/Dolby Atmos encoded disc. You might also need to change the Sampling Frequency setting to 192kHz with the Auto setting too.

OK this is where I am. I am going to forget about the CD Player. Nothing seems to work. I guess I can forgo the surround for stereo…although $3K for a system that does not deliver se ems crazy. Now the problem is just to get the Sonos Arc and LG C1 to put out Atmos. It does not even do that. I have tried to stream Atmos content from HBO max and don’t get Atmos. Also tried to stream from Amazon prime and nothing. I just read, although I don’t know if it is true, that the C1 only supports Atmos through the internal speakers. What is this?? I am ready to pack all this Shi….. up and take it back while I still can. I am going to call LG later today to see if they can help. Sonos is useless they are they have the worst support. It really is a joke. It would seem they would want to help to keep their $1500 sale. Thanks for your ear.

I think you are perhaps misunderstanding some things here - the HDMI pass-through option would not apply to your built-in TV Apps - if they are playing Atmos audio they are using the TV to do that. It will be DD+ (Atmos) and that should (certainly) output via your HDMI-2 port using ARC or eARC, it sounds like there is something amiss with your setup. Firstly ensure you are using HDMI cables that have HEAC support - the original cable, for example, that came with your Arc is best to use here? I would check your TV settings - these (below) are the ‘usual’ settings that are common for the majority of LG TV’s running WebOS to provide Atmos Audio out:

• Simplink & Auto-Power Sync: ‘ON’
• Sound Out: ‘HDMI ARC’
• HDMI Input Audio Format: ‘Bitstream’
• Digital Sound Out: ‘Pass Through’ or use Auto (do not set to PCM)
• eARC: ‘On’
• DTV Audio: ‘Auto’

Hope that assists.

To perhaps assist you to test the Atmos audio-out to the Arc from the LG C1 TV when you have the settings in place, launch the TV’s built-in Netflix App (you will need the Premium Netflix subscription to play Atmos audio) and play any movie that has the Atmos audio logo next to its title, such as the movie ‘6 Underground’ and open the Sonos App’s ‘Now Playing’ screen when the Arc room is in focus to see the codec in use, or alternatively goto “Settings/System/About My System” in the app and look at the Audio-In next to the Sonos Arc in the device list.

First let me thank you for all of your help. So here is where I am. I am using all updated cables high speed 2.1 that support Atmos. I swapped out the cable to the ARC and am using the cable that came with the ARC just in case. I now am at least getting Dolby Vision on the TV banner but no Dolby Atmos. Also no Atmos in the sonos app. I have been trying every setting. It is definitely not the Sonos Arc because I have used my old Vizio Atmos sound bar with the same results. I joined Netflix premium to test another source. So Netflix, Amazon Prime, and HBO max all with the same result. I am going to keep trying for a few more days before packing everything up and sending it back for a refund. I also will go to Best Buy and purchase a Vizio Elevate this weekend….set it up and see what happens and if I like it better than the Sonos. I have a couple of weeks to return it. I still think that there is a setting I am missing on the TV…..I will keep trying. Thanks so much for your guidance it is greatly appreciated. If you can think of anything else to try let me know. 

Have you spoken to LG Support to see if they are able to assist you with the TV settings? - they can perhaps check things with you over the phone.

https://www.lg.com/us/support/telephone

Listen……..I have been on the phone with LG for hours and hours and hours day after day after day.

Sometimes I get someone who does  not know anything. I am beginning to wonder if this TV even

supports Atmos. I now am thinking after reading something on line that the TV will show Dolby Vision and not Atmos even if Atmos is present. How will I know…..well the sonos app will not show it and the sonos people said it only reads what the TV is sending. But thanks. I’ll keep trying. The ARC sounds fantastic just with the Dolby Vision. I am still considering the Elevate for the DTS. I’ll keep you all posted.

I feel your pain G.B.D.  I’m also frustrated by the fact that the Sonos Arc doesn’t support DTS audio and there aren’t many 4K Blu-Ray players that can convert DTS to multi channel LPCM.  Peter Pee on his YouTube channel recently announced what probably every Arc owner in the country has been clamoring for, DTS support will be added to the Sonos Arc via a software update before the end of the year (2021)!  Can someone from Sonos please verify this, its got me very excited!

Yes, DTS is coming to all Sonos home theater products via a software update later this year 

Thanks for the news………..I did pack up my ARC and sub-woofer and sent them back for full refund. I was going to purchase something else but have not found any I like. I may wait until the the software update is up and running before repurchasing the ARC and sub. Sometimes promises are not kept.  In the meantime I will continue to audition other sound bars. I do have my eye on the Elevate. Thanks again.

Your LGC1 won't pass through DTS no matter what Sonos does. LG doesn't support it.

I have a similar setup expect I'm playing my DTS disks on a PS5. It's converting DTS to LCPM surround no worries. 

I reckon the device that isn't playing ball is your blu ray player. Do you have a console that can play Blu rays?

"Your LGC1 won't pass through DTS no matter what Sonos does. LG doesn't support"

That's why I wish this $900 soundbar had at least 1 HDMI input/ pass through so people did not have to deal with having earc on their TV or if TV supports dts through arc/earc. 

I currently have a Vizio atmos sound bar Model SB36512-F6. I also have an LG UBK90 blu-ray player. Should I have my blue ray player connected to the sound bar? Currently I have it connected directly to the TV. As you can probably tell I am not so savvy with all this audio video hook up. Help

Yes, connect the Blu-ray player to the soundbar’s HDMI IN port.

I have CX with an Arc connected via eArc, it was interesting reading all of the issues you’ve had. My setup has been pretty seemless.

Web OS apps like Apple TV and Netflix both happily pass through Atmos. Just the other night we watched Harry Potter and the Chamber of Secrets on 4K Blu-Ray via our Sony 4K player. That movie has a DTS-X sound track and the Sonos app identified it as 7.1 Bitstream. Something in the chain is doing it’s job.

I think that LG 4K player maybe the cause of some issues. None of their models are reviewed favourably and they seem to have compatibility issues with certain discs.

With your current setup GuitarSuperstar is correct, if you want DTS audio you’ll need to connect it directly to the sound bar. Something not possible on the Sonos Arc.