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Noisy digital audio on LG TVs

elvisizer

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I had dropouts with an LG CX optical out to a Topping D90se dac, though the same CX output is accepted no problem by a mytek dac. Both of those are ESS based, Sabre 9028 Pro in the mytek, 9038 Pro in the topping.
Using HDMI eARC with a 2nd CX output to a denon AVR has had no issues for me, fwiw the denon has an AKM dac.
 

Diego Humanes

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Dear audio science enthusiasts,

I recently got one of those popular LG C1 TVs. Since I only have a stereo system, but several HDMI sources plus using the TV's apps, I went the easiest audio route for my setup:
(source) -> TV -> optical out (PCM) -> DAC -> analog Preamp
As I realized only after my purchase, the optical out of LG TVs seems to be quite terrible (noisy) across models and LG seems to not care about it. Most clearly it's stated in an FAQ by JDS Labs, who measured SINAD of 81db from one LG TV. Quite a few people complain about stuttering audio as well, coming from some DAC's jitter handling not "expecting" such a terrible source signal. Now my DAC doesn't have that problem*, but I'm still curious if using an HDMI audio extractor may yield a better signal.
So my question is if anyone has tested or seen this measured for LG TVs in particular: optical out vs extracted from ARC HDMI?
I've seen at least one report where people have tried the extractor route without solving their stuttering audio problem, which leads to the question if LG has only messed up the optical output or digital audio output in general.

Here's a thread from AV Forums about the topic.

* DAC is a Lake People RS-06, which the manufacturer claims has a resampling and re-clocking implementation that "almost completely rejects jitter". I have no idea to which % this is marketing mumbo jumbo, but at least I get no interruptions to audio.
My new Samsung S95B tv causes stuttering on optical through an SMSL SU-8 dac, on both DVB and USB media. It sounds ok through my Onkyo A-9010 stereo amplifier toslink input with the same cable, so I guess the SMSL is more sensitive to jitter.

I also gave a thought to a (e)ARC HDMI extractor, there are some with I2S output for 50$ on AliExpress, but guess how much jitter they yield.

My S95B premium tv also resamples 44.1 KHz content to a constant 48 KHz, so I'd rather use a streamer for native samplerate and less jitter playback.

To me the best scenario with a Sony or Android TV based one is connect the DAC by usb. Usb has better jitter correction. Or a new dac with great toslink jitter rejection. Most recent ones by Topping or SMSL have very low jitter and they have a jitter sensitivity setting. But if the tv does 48 KHz resampling it is useless, you need a streamer for CD content.
 
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rossfoo

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I'm in the same boat now with an LG C2 and a SMSL M500.

@JunkHippo or anyone else. Did you end up with an extractor of some sort? Do you guys think there's any point in keeping the SMSL (vs option 1 below)?

I'm a total beginner here so any advice would be much appreciated. As far as I've read about this issue the options are:
  1. Swap SMSL
    1. With an AVR
    2. Wireless stream (e.g. bluesound node)
  2. Extractor (that doesn't degrade quality beyond the original issue...)
  3. Update SMSL firmware and pray
Last question: If I'm going to use an extractor does anyone know if eARC can be used essentially as an "audio out" from the TV to the extractor?
 
OP
JunkHippo

JunkHippo

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I can share that I have an eARC extractor now and go via the Toslink output to my DAC. For your last question @rossfoo I can confirm, basically an eARC HDMI port sends the digital audio and the extractor takes that and puts it out via coax or Toslink to your DAC.
However since I didn’t have sound dropouts or similar issues that would be easily identifiable by ear, I can‘t say for sure if anything changed. Very subjectively I would say yes, to the better, but probably that’s confirmation bias. Anyway the extractor was cheap, is easily hidden behind the TV, works without issues, and is likely not worse than the compromised optical out of the TV. So I‘ll leave it installed.
If I ever get a DAC with two optical inputs (hunting for 2nd hand Benchmark DAC3), I might try switching back and forth between TV and extractor, to listen for differences.
Currently that would involve plugging cables in and out, making for a less immediate comparison.
 

james57

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Kind of the same setup LG G1 to oppo(preamp dac) to amp.. I have tried both optical and HDMI arc. I must be tone death, see no difference in audio quality and have not experienced drops. But on the functionality side its different. When you use hdmi arc you can control the vol and the lg remote is a piece of sh.. hence why I prefer using optical and using the oppo remote for vol ctrl. Also opti is always linked. HDMI arc seems to need a new handshake each power on, which is kind of anyoying. I am running a 2.1 setup so no format difference between both path, I know optical is more restrictive for ATmos and multi channels, think over 5.1 but not my case.
 
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rossfoo

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Kind of the same setup LG G1 to oppo(preamp dac) to amp.. I have tried both optical and HDMI arc. I must be tone death, see no difference in audio quality and have not experienced drops. But on the functionality side its different. When you use hdmi arc you can control the vol and the lg remote is a piece of sh.. hence why I prefer using optical and using the oppo remote for vol ctrl. Also opti is always linked. HDMI arc seems to need a new handshake each power on, which is kind of anyoying. I am running a 2.1 setup so no format difference between both path, I know optical is more restrictive for ATmos and multi channels, think over 5.1 but not my case.

Your Oppo unit doesn't have an HDMI in does it? What do you use to convert from HDMI out?
 

james57

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Your Oppo unit doesn't have an HDMI in does it? What do you use to convert from HDMI out?
The oppo 105 has one hdmi in but the lg only has several hdmi in no out, this is why I am sending the audio via hdmi arc in lg and hdmi out arc oppo. Hope this clarifies. I am currently running optical for ease of use but both works fine.
 

ElNino

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I deleted an earlier post because I misread JDS Labs' website, but I'm still confused by their measurements. It's clear they were using a 24-bit test signal, but the LG optical output is locked at 48kHz/16-bit depth (see the manual). So you expect to see some quantization artifacts with a 24-bit input signal. They don't say what input sampling rate they're using, but all of the artifacts are about -90dB down, which looks to me like some combination of quantization and mid-quality software resampling.

I don't think the data supports the conclusion they're giving that there's anything actually wrong with the data on the optical out, beyond a high level of jitter that the ESS receiver can't cope with. (Maybe there's more data on a forum somewhere?)

I've never had an issue with my LG TV's optical out and several DACs, but I also haven't tried it with an ESS DAC.
 

james57

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,
I deleted an earlier post because I misread JDS Labs' website, but I'm still confused by their measurements. It's clear they were using a 24-bit test signal, but the LG optical output is locked at 48kHz/16-bit depth (see the manual). So you expect to see some quantization artifacts with a 24-bit input signal. They don't say what input sampling rate they're using, but all of the artifacts are about -90dB down, which looks to me like some combination of quantization and mid-quality software resampling.

I don't think the data supports the conclusion they're giving that there's anything actually wrong with the data on the optical out, beyond a high level of jitter that the ESS receiver can't cope with. (Maybe there's more data on a forum somewhere?)

I've never had an issue with my LG TV's optical out and several DACs, but I also haven't tried it with an ESS DAC.
the 105 uses the es9018, no issue here
 

Rottmannash

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I deleted an earlier post because I misread JDS Labs' website, but I'm still confused by their measurements. It's clear they were using a 24-bit test signal, but the LG optical output is locked at 48kHz/16-bit depth (see the manual). So you expect to see some quantization artifacts with a 24-bit input signal. They don't say what input sampling rate they're using, but all of the artifacts are about -90dB down, which looks to me like some combination of quantization and mid-quality software resampling.

I don't think the data supports the conclusion they're giving that there's anything actually wrong with the data on the optical out, beyond a high level of jitter that the ESS receiver can't cope with. (Maybe there's more data on a forum somewhere?)

I've never had an issue with my LG TV's optical out and several DACs, but I also haven't tried it with an ESS DAC.
I've had no issue with my LG C9 and the Topping D90 SE.
 

jasonhanjk

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I have an LG TV here converts my 24 bit file into 16 bit output. Same goes to Samsung. :facepalm:
 

MontyGibbon

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Hiya. Can I interpose to ask a question?
The gear in question is:

- LG OLED65C8PLA telly
> Optical cable (can't remember brand)
> Topping D70 DAC

The circumstances are:

My D70 died a couple of years or so ago. Fuses checked but, it wouldn't power on.

In the run up to that sad event, there'd been an increasing number of pops/drop outs but, only when using the D70 to process the telly signal via an optical cable.

I put the D70 demise down to a Topping QC issue. That was along time ago and, I'd not given it any thought recently ~ 'till bumping into this thread.

My question ~ could the D70 failure have arisen from a problem orginating in the LG optical implementation?

Just curious; I'm well through the bereavement period. That said, 'it' did influence my decision not to buy anymore Topping products.
 
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