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TCL Roku TV - Optical Audio Passthrough

I bought a TCL 65R625 about a week ago.  It's an absolutely stunning television, and on the whole I have no complaints, but the way it handles the optical audio passthrough seems to be somewhat broken.

My receiver is very old (a Sony STR-DE885); it can't do HDMI and so no ARC.  It can do Dolby Digital (non-plus) and DTS, quite well, and I'm loathe to replace it.  In any case, when I plug the receiver into the TV using an optical cable, the TV "detects" it as only being capable of 2-channel sound.  The sound works in auto-detect mode, but everything is 2-channel.

If I switch the TV to a more specific audio mode (DD or DD/DTS), the TV will passthrough Dolby Digital signals, but if I try to play something with a DD+ signal, the audio is broken every few seconds, as if the TV were struggling to decode the DD+ signal in a timely fashion.  The receiver reports that the sound is Dolby Digital, though, when it comes through.

My prior TV (a 1080p Sharp Aquos, circa 2013) handled audio passthrough without a hitch.  My Tivo Roamio, itself a pretty old piece of hardware, also has zero problems converting DD+ signals to DD for my receiver.

I wouldn't even mind too much if the TV simply gave me 2-channel audio when it encounters a DD+ signal, instead of trying to convert it to regular Dolby Digital.  The main thing is that I have old and young people in the house, who don't know how or can't be bothered to play with different inputs on the receiver or audio options in the TV menu every time they watch a given piece of content.  The whole appeal of audio passthrough on a TV is that you don't have switch your inputs every time you decide to watch different content.

With all of that said, I have two questions:

1.) It seems clear that the TV is at least trying to downconvert DD+ to DD, and thus presumably it was designed with that capability.  Was this capability broken by a software update, and/or can it be fixed by a future software update?

2.) Is there some sort of setting or quirk that I'm missing?  I've tried with ARC enabled and disabled, with the TV's speakers enabled and disabled.

Appreciate your time and attention.

Level 8

Re: TCL Roku TV - Optical Audio Passthrough

I am having the exact same issue. I have HDMI out and 4 inputs. Two opticals.


Onkyo Ts706

I only receive Multichannel stereo. No Dolby digital. I have it hooked up the identical way as my last TV. 

I have tried many different settings. Still no digital? Piggy backing on your thread. Hope you don't mind.

Connections ARC HDMI from TV to non ARC out on receiver.

Optical from TV to Optical 1 on receiver (GameTV)

From DVD out To receiver In (DVD) HDMI 1. This Tv switches from DVD when DVD is powered on. Just as i would hope. I am able to see volume on TV from receiver as i adjust it. Receiver powers on when I power on TV. Just as i would expect. Just no dolby digital displayed on my receiver. 

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Level 8

Re: TCL Roku TV - Optical Audio Passthrough

I have solved my issue. Hopefully it works for you.

In settings Audio Set Speakers to off

S/PDIF and ARC to PCM-Stereo

That is all on TV side.

I cannot speak for your receiver. 

But as soon as did the TV functions and Started Guardians back on Dolby Digital was displayed.

If you need further details let me know


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Re: TCL Roku TV - Optical Audio Passthrough

Thank you for your replies.  I don't think yours is the same problem as mine; I did try the PCM-Stereo setting on the TV one more time, per your suggestion, but no luck - but there's at least one, possibly crucial difference between your situation and mine.  You have an HDMI cable hooked up to your receiver.

I'm running purely through optical.  The following options in the TV's audio settings yield 2-channel sound in all content:

  1. Auto-Detect
  2. Auto Passthrough
  3. PCM-Stereo

If I choose either Dolby Digital or Dolby Digital/DTS, I get DD sound in DD content, which is great, but in Dolby Digital PLUS content, I get DD sound that breaks up every few seconds, as if the TV were struggling to convert the audio stream. 

In practice, this means that the only set-it-and-forget-it options in the TV menu are the ones which give me 2-channel sound across the board.

I may just buy a different streaming device through which to watch 4k/HDR content, though based on this experience, I'm beginning to wonder how/whether to tell which devices can do the job.  The TCL's specs, after all, would lead you to believe that it can do passthrough purely through optical; I had to buy it to find out otherwise. 

Level 8

Re: TCL Roku TV - Optical Audio Passthrough

So, I did some tinkering. 

Mine will only work when I put me setting on my receiver to CD. 

It does not work on the game mode tv. It was just coincidence with the PCM on the TV. It works on auto detect. 

My issue was with my receiver. 

But I now have Dolby Digital. 

I assigned my CD to Opt 1

Level 8

Re: TCL Roku TV - Optical Audio Passthrough

My problem seems similar to your problem.

I just bought a 55” TCL Series 6 2020 model (635). I am attempting to feed all sound from the TCL to a outboard PS Audio Sprout integrated amp. This includes output from YouTubeTV, Netflix, Prime Video and other apps—especially PLEX which I use for audio and video streaming. My sole connection is a digital optical cable from the TCL digital optical output port to a digital optical input port on the integrated amp

There is sound, but it is choppy and seems to randomly break down with very short gaps and perhaps other artifacts. It is unlistenable.

I am not sure that I have all the audio settings right on the TCL, though I have played around with them to no avail. 

I would be delighted just to have standard 2-channel sound. I do not need any DD effects. I mostly play straight audio, or videos of orchestral concerts that include straight 2-channel audio.

I am getting ready to replace this specific TCL unit suspecting it is defective. But perhaps I just do not have the settings right. I have had these sources fed to earlier TVs using a Roku Stick or Roku Ultra, and all worked fine. So I know there is no problem with the source material.

Advice please?

Level 8

Re: TCL Roku TV - Optical Audio Passthrough

I have the same set up as the OP (with an old sony str de935 receiver), but instead of choppy audio, mine just cut out and has not come back. Everything else is identical to the OP, in terms of getting stereo in other modes. But the TV isn't outputting/passing DD/DTS when that's chosen in its menu. Very very frustrating, since it is clearly capable. Tried resetting the receiver, but it really doesn't seem to be a receiver issue epithet. The TV just seems very finicky to output DD/DTD over optical. Any solutions or just don't buy Roku TCL TVs? That's my impression at this point

Level 8

Re: TCL Roku TV - Optical Audio Passthrough

Woke up this morning and now the TV outputs DD/DTS just fine to the receiver. I can't tell whether it's the TV or the receiver at this point.

Re: TCL Roku TV - Optical Audio Passthrough

Yeah I've given up at this point.  The TV is still great overall, and 2-channel sound up-mixed via Dolby Prologic is certainly an adequate complement.

I remain frustrated that neither the TV, nor (apparently) any of the newer streaming devices, are capable of handling DD/DTS over optical on a set-it-and-forget-it basis, though.  Nor can the TV even pass through surround signals over optical--I suppose because it's not equipped to "detect" the receiver's capabilities unless connected via HDMI.

As I said in the OP, both my old television and my old Tivo (both limited to 1080p) effortlessly and automatically downmixed DD+ signals from e.g. VUDU when connected to the stereo via optical.  The old TV did passthrough over optical.  These are utterly prosaic features that I took for granted. 

All of the marketing/reviews falsely report that the new TV can do DD/DTS passthrough over optical, which is another reason that this issue frustrated me.  I assumed the problem must be on my end.  Nope, clearly not.

But apparently we're the only people to notice or care.  Every so often I'll google this issue in case there's been an update; it's a little surreal to find that my own, unresolved thread is consistently the top result.

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Level 8

Re: TCL Roku TV - Optical Audio Passthrough

I think the reason we are the only ones complaining is probably because there aren't many people with Sony receivers this old. I assume it works with newer receivers. 

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