About the sound quality of TVs optical outs

[gino1961]

Hi to All and sorry for the weird question
I have the feeling that the optical out from TVs when routed to a good dac maybe reclocking the signal is not bad at all
I say this because i have been impressed by the quality of some sonic effects while watching movies
Sometimes their reality is scaring and exciting
Actually i am going to use them to judge my system
am i crazy? Am i hearing things?
What is your opinion?
Thanks and kind regards
Gino

 

[voodooless]

am i crazy?

Who knows… I’m no expoert on those matters

Am i hearing things?

Clearly, so we can assume the DAC works.

What is your opinion?

Well, every DAC with spdif does clock recovery on the incoming signal, and the resulting jitter is always lower than what came in. Is this audible? Probably not.

Besides? What is your reference? If you think the DAC sounds so special, what does not sound special to you?

 

[gino1961]

Who knows… I’m no export on those matters

Hi you mean expert ? thank you for your reply I have to say that since the beginning my feelings towards digital have been mixed
and not only mine Some of the first cd players did not sound right And only a few ones sounded like analog that was the reference for sound
I think that the secret is in the dac
I have an old pro dac the Apogee Rosetta 200 that would make an audiophile call an exorcist
I have fed it even with a 70 euro tv box through toslink and the sound was quite ok because it does a reclock internally
A very good dac should do this always i.e. not being source dependent Always imho of course
I guess that with dacs that do not reclock the outcome should be dependent from the quality of the incoming signal ?

Clearly, so we can assume the DAC works.
Well, every DAC with spdif does clock recovery on the incoming signal,

Thank you very much I was thinking the contrary Then changing source should have no effect on the sound ?

and the resulting jitter is always lower than what came in. Is this audible? Probably not.
Besides? What is your reference? If you think the DAC sounds so special, what does not sound special to you?

as a source lately i have been using a cheap streamer from SMSL the dp3 connected via AES/EBU to the Apogee above mentioned
If i take one wav file i put it on a usb pen and stick the pen in the dp3 or in an usb slot of the TV the sound that comes out of the Apogee is very very similar
i have seen dedicated audiophile streamers hugely expensive
What they provide more than a usb slot in a TV used as reader ?

 

[voodooless]

as a source lately i have been using a cheap streamer from SMSL the dp3 connected via AES/EBU to the Apogee above mentioned
If i take one wav file i put it on a usb pen and stick the pen in the dp3 or in an usb slot of the TV the sound that comes out of the Apogee is very very similar
i have seen dedicated audiophile streamers hugely expensive
What they provide more than a usb slot in a TV used as reader ?

Well, yeah, generally, digital is digital, so the bits that go to the DAC are the same in many cases. So there is no reason to think they will sound any differently.

As for expensive audiophile streamers: as with all audiophile stuff, it’s mostly marketing nonsense and it won’t hold up to some basic scrutiny.

What they do provide is convenience and compatibility over a TV, but even a cheap streamer will do that.

Some TVs though are known for poor digital audio quality, ranging from massive jitter on the toslink output, to extremely poor (audible) resampling. Those may exhibit notice differences in sound quality, hiccups, or sometimes even no sound out of the DAC at all.

 

[tmtomh]

Hi to All and sorry for the weird question
I have the feeling that the optical out from TVs when routed to a good dac maybe reclocking the signal is not bad at all
I say this because i have been impressed by the quality of some sonic effects while watching movies
Sometimes their reality is scaring and exciting
Actually i am going to use them to judge my system
am i crazy? Am i hearing things?
What is your opinion?
Thanks and kind regards
Gino

You’re not crazy. In terms of sound quality and practical data integrity, the digital output of the TV’s optical jack is essentially identical to its HDMI output (and any other digital output it might have).

 

[DVDdoug]

And only a few ones sounded like analog that was the reference for sound

Analog is inferior in every way. By the end of the analog era analog studio tape was probably better than human hearing but never as good as CDs. Analog home audio never was never better than human hearing. On vinyl records, you can hear background noise between tracks (and sometimes nasty clicks & pops during the music), there are frequency response variations, and occasionally audible distortion. Cassettes have audible hiss and poor high-frequency response. CDs are generally better than human hearing.

The ONLY time I've heard a defect or difference from a "DAC", it was a soundcard that made noise when the hard drive was accessed. I never heard anything wrong with the DAC that was built-into my 1st CD player 40 years ago!

S/PDIF doesn't have enough bandwidth to support the Blu-Ray formats. But a DVD played through S/PDIF is sending the same exact data as HDMI.

Some TVs have some some kind of problems with certain DACs. I think it's LG TVs and maybe they get clicks or dropouts... Whatever it is, it's an obvious and easy-to describe problem.

When digital data gets corrupted it's usually pretty obvious. It doesn't degrade gradually or "slightly' like analog sometimes does. This an imperfect example but one bit in your bank account flipped from a 1 to a zero, or vice-versa, is equally as likely to cause a 1-cent error or a billion dollar error! Another example I often use is these posts on the Internet... If there's a misspelled word in my post you can be pretty sure it was MY mistake and the data didn't get corrupted traveling through all kinds of connections all over the world...

 

[gino1961]

Hi thank you very much to All of you for now
I am traveling now but tomorrow i will reply you more extensively
Especially regarding the analog sound issue
Have a nice evening and thanks again

 

[gino1961]

Well, yeah, generally, digital is digital, so the bits that go to the DAC are the same in many cases. So there is no reason to think they will sound any differently.
As for expensive audiophile streamers: as with all audiophile stuff, it’s mostly marketing nonsense and it won’t hold up to some basic scrutiny.
What they do provide is convenience and compatibility over a TV, but even a cheap streamer will do that.
Some TVs though are known for poor digital audio quality, ranging from massive jitter on the toslink output, to extremely poor (audible) resampling. Those may exhibit notice differences in sound quality, hiccups, or sometimes even no sound out of the DAC at all.

Hi again and thanks a lot for the very kind and valuable advice
Leaving aside extreme cases for a moment and considering that, at least in my opinion, a high-quality DAC should always impose its own clock, I believe that in a digital chain, the crux of the matter is the DAC itself.
I don't have a very good DAC, but it reclocks the input digital signals.
I've connected everything to it, from a $60 TV box to a CD player, DVD player, and streamer... the sound, at least with CD files, is practically always the same.
So if I had to upgrade, I'd opt for a DAC that reclocks to ensure consistent results. And good sound of course.
There's just one problem: I can't tell which ones do it and which ones don't. They do not say clearly.
I am very interested in SMSL and Topping dacs ... but i do not know if they reclock or not.

 

[gino1961]

You’re not crazy. In terms of sound quality and practical data integrity, the digital output of the TV’s optical jack is essentially identical to its HDMI output (and any other digital output it might have).

Hi again and thank you very much indeed for your helpful advice
I have come to the conclusion that the key unit is the dac. And that reclocking of the incoming digital signals is a must. The clock is so important that i see even clock generators in the pro market.
I wonder how can i understand if a dac reclocks or not. This kind of dacs should provide a consistent sound with different sources Even very cheap ones like a refurbished Windows pc and maybe a usb to spdif or toslink converter. Like this one for instance ...

PO100 2024

Foshan ShuangMuSanLin electronics Co., LTD. founded in 2009 which located in Shenzhen, China. And our branch company VMV Technology(HK) Company Limited registered in HK in 2013. Our company is specialized in the audio DAC, stereo headphone amplifier, power amplifier, and with own R&D...

www.smsl-audio.com

 

[gino1961]

Analog is inferior in every way. By the end of the analog era analog studio tape was probably better than human hearing but never as good as CDs. Analog home audio never was never better than human hearing. On vinyl records, you can hear background noise between tracks (and sometimes nasty clicks & pops during the music), there are frequency response variations, and occasionally audible distortion. Cassettes have audible hiss and poor high-frequency response. CDs are generally better than human hearing.

Hi thanks a lot for your kind and precious advice
My memories go back to the early '90s The cd players sound was causing some discussions Like not being musical enough
I remember some units that sounded very musical The Rotel RCD-965 BX and an old Grundig 7500
The sound was bigger thicker with good separation and soundstage ... i still like those units a lot
I had different cd players but their sound was less involving
Again i think that a great dac can solve most of the issues

The ONLY time I've heard a defect or difference from a "DAC", it was a soundcard that made noise when the hard drive was accessed. I never heard anything wrong with the DAC that was built-into my 1st CD player 40 years ago!
S/PDIF doesn't have enough bandwidth to support the Blu-Ray formats. But a DVD played through S/PDIF is sending the same exact data as HDMI.

Thanks a lot I am not much on Blu Ray Just cds and dvds So the limit is 16/48 I do not know why but i prefer this format to the cd format
Dat uses 16/48 There must be a reason I listened to some dat tapes and found them completely satisfying No need for analog
Actually i have a friend with a huge LPs collection He despises the cd format
We made some recording on dats .... he had nothing to criticize and like them a lot at the point that he has started to record his more precious vinyls

Some TVs have some some kind of problems with certain DACs. I think it's LG TVs and maybe they get clicks or dropouts... Whatever it is, it's an obvious and easy-to describe problem.
When digital data gets corrupted it's usually pretty obvious. It doesn't degrade gradually or "slightly' like analog sometimes does. This an imperfect example but one bit in your bank account flipped from a 1 to a zero, or vice-versa, is equally as likely to cause a 1-cent error or a billion dollar error! Another example I often use is these posts on the Internet... If there's a misspelled word in my post you can be pretty sure it was MY mistake and the data didn't get corrupted traveling through all kinds of connections all over the world...

Very very interesting Today my most used streamer is a Chromecast Ultra ... i could buy a HDMI spdif extractor and try its outs

this would be a little extreme ... but i have to check one for sure
I hope that the HDMI out of TVs will not have the issues you mentioned

 

[voodooless]

So if I had to upgrade, I'd opt for a DAC that reclocks to ensure consistent results. And good sound of course.

Your DAC is quite fine. 103 SINAD and 114 dB SNR. It should be fully transparent already. So really, there is nothing to upgrade in that regard.

Your DAC comes with an ASRC (asynchronous sample rate converter). Most modern DACs don’t have those. Regardless, they will give excellent (indistinguishable) results.

If you “upgrade” do it for features your missing out on now, not sound quality.

 

[TurtlePaul]

Not every TV has perfect optical output. My LG 48GQ900-B has the following frequency response via its optical output (green) and headphone output (red).

 

[gino1961]

Your DAC is quite fine. 103 SINAD and 114 dB SNR. It should be fully transparent already. So really, there is nothing to upgrade in that regard.
Your DAC comes with an ASRC (asynchronous sample rate converter). Most modern DACs don’t have those. Regardless, they will give excellent (indistinguishable) results.
If you “upgrade” do it for features your missing out on now, not sound quality.

Thank you very much again. I understand now that if i hear some issues they will not be related to the dac It is a good conclusion
I will dedicate more to the room speakers and power amp I have already a very old preamp that i like enough An old Electrocompaniet ec 4.5 that i bought 2nd hand
I bought it mainly because provides both unbalanced and balanced ins and outs I find this convenient No noise quite transparent
Thank you very much and kind regards gino

 

[Petrushka]

I thought SPDIF only supported two channels.

Back when I could hear better, I thought blue ray sound was distinctly better than DVD.

The same quality as CD, but multichannel.

 

[gino1961]

Not every TV has perfect optical output. My LG 48GQ900-B has the following frequency response via its optical output (green) and headphone output (red).

View attachment 463009

Hi very interesting indeed I wonder about using the headphone out now impressive flatness indeed
What about the HDMI extractor solution ? they are little boxes that provide a pass through for the video and an optical out Their price is absolutely affordable
Have you checked also the HDMI out quality ?

 

[gino1961]

I thought SPDIF only supported two channels.

Hi thanks a lot for your kind advice. I am listening only through two speakers I cannot stand multiple speakers in the room
In particular i hate the center channel The worst thing that they could think of Imho absolutely not needed
I can get voices coming perfectly from the center even with a stereo set-up

Back when I could hear better, I thought blue ray sound was distinctly better than DVD.
The same quality as CD, but multichannel.

i listen only cds and some concerts on dvd I know i am missing something Maybe in the future

 

[TurtlePaul]

Hi very interesting indeed I wonder about using the headphone out now impressive flatness indeed
What about the HDMI extractor solution ? they are little boxes that provide a pass through for the video and an optical out Their price is absolutely affordable
Have you checked also the HDMI out quality ?

I have not tried an HDMI audio extractor, but it is an idea.

 

[gino1961]

I have not tried an HDMI audio extractor, but it is an idea.

I think i have one
I will try it between the Chromecast and the TV
I am curious
Maybe it comes out that the Chromecast plus a suitable app can work as streamer
I will report
Thank you very much
Kind regards Gino

 

[Petrushka]

Hi thanks a lot for your kind advice. I am listening only through two speakers I cannot stand multiple speakers in the room
In particular i hate the center channel The worst thing that they could think of Imho absolutely not needed
I can get voices coming perfectly from the center even with a stereo set-up

i listen only cds and some concerts on dvd I know i am missing something Maybe in the future

I used to master DVDs from files made from tapes.

DVD is a bit like MP3, in that there are different levels of compression available.

I suspect that applies to audio as well as video.

 

[gino1961]

Hi thank you for the very interesting advice
The only comparison we made was LP vs dat i guess 16/48 format
The outcome was very positive
My feeling is that 16/48 is a very good format