Audio quality query

[Lodzilla]

Hi all,

I'm about to buy a new Sony 2018 XF85 TV to go with a the HT-ZF9 soundbar, linked together by HDMI over the ARC ports. The TV is 4K and the soundbar does Dolby Atmos, so I'm looking forward to plugging in my STB and watching BT Sport 4K with Dolby Atmos sound. Lovely.

My question is this: I know that in theory it would be best to plug the STB into the soundbar and let the bar relay the video to the TV over ARC; however if (for both marital bliss & wall mounting reasons) I had to plug the STB into the TV instead and relay the audio to the soundbar over ARC, would the Atmos audio quality be lower, assuming it's Atmos over DD+?

I ask because I saw the TV specifications snippet below:

ARC (HDMI IN 3 only)
Two channel linear PCM: 48kHz 16 bits, DD, DD+, DTS

Two channel PCM says 'stereo' to me (perhaps incorrectly), yet the DD+ suggests otherwise. So it got me wondering, even though it would likely passthrough the Atmos signal to the soundbar, whether it would be of noticeably lower quality compared to plugging the STB directly into the soundbar?

Happy to be corrected on any misunderstandings/assumptions.

Thanks

[Pascale_F]

Hi Lodzilla,

Welcome to the community.

I'll see if i can track down an answer. Maybe someone else in the community has an idea in the meantime.

Thanks,

Pascale

[Lodzilla]

Thank you, Pascale. I really just want to know whether the quoted TV specifications mean that my 5.1 / DD+ input gets downgraded over ARC.

Many thanks.

[royabrown · Accepted solution]

Hi @Lodzilla

DD+ can encode up to 13.1 channels of audio, and your soundbar decode the DD+ back into as many channels as it can handle, so there should be no problem passing 5.1 over it.

However, I can see no evidence that either this TV or DD+ generally can handle Dolby Atmos, so I don’t think that any Dolby Atmos that the YouView box plugged into the TV could do would make it through, or possibly even to, the TV.

I might be inclined, in your situation, to rig an HDMI cable to the TV, another to the soundbar, and have a short HDMI tail from the Atmos source YouView box, and couple all 3 with an HDMI switch, normally left in direct YouView box to TV mode, for domestic bliss, but switchable by you on demand for audio bliss.

Except that when I tried something similar, the switch wasn’t able to function as a dumb enough connector to just do passthrough, nor as a smart enough one to pass what I wanted (which was ARC, in my case). So I had to replace the switch with an HDMI coupler, and I couple whichever lead I want myself; mildly inconvenient, but not insurmountable.

I tried a couple of different switches, but no go. However, maybe you will find a switch smart enough for your needs.

[Lodzilla]

Hi @royabrown,

Many thanks for your reply - very useful. I did consider an HDMI switch but, as you suggest, I couldn't be sure that any I looked at would do quite what I wanted.

On the Atmos front, my understanding was that streamed Atmos (I.e. from an STB) would be over DD+ rather than TrueHD as it's compressed. So while I could see ARC could take DD+ I wasn't sure if the 2.1 PCM drop of the ARC out compared to the 5.1 PCM of HDMI IN would have any effect on the DD+ channel.

In the end I plugged it into the STB directly and just did a really neat job of the cabling, so I had no complaints from my better half.

Thanks for your advice!

[Win_88 · Accepted solution]

Hi Lodzilla,

You have got the right idea here. If you connect the STB to the TV, it will output 5.1 audio adequately but it will not be in the Dolby Atmos format. So your best bet is to connect the STB to the soundbar directly and let is pass the video signal through to the TV. Now whether you will actually hear a difference with your own ears between the two connection methods is an entirely different story as it depends on how sensitive your hearing is.

Anyway, I'm glad that all turned out okay with the missus on the cable management front. That's something to be proud of

Win_88

[Lodzilla]

Thanks @Win_88. That's great confirmation. I'd rather get the best quality sound whether I can tell or not so direct to STB is the way to go.

And yes, it's amazing how a few cables showing is suddenly no longer a problem when I suggest the alternative is more holes in the walls 😂

Thanks.