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TV as streamer: Shocking measurements

3cx15000a7

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Hi all!

At first, compliments for all the good objective reviews with detailed measurements ! Nice to see there are also review places where cables not magically make stereo from mono.

I have the following setup:

LG Oled55C8 - > Optical out -> Musical Fidelity V-Dac 2 -> Marantz SR6001 -> B&W CM9 (stereo pair, I went away from surround long ago)

I mostly stream music from spotify using my tv.

I was wondering if it was worth to upgrade to a stand-alone streamer instead of using my TV as streamer. Therefore I borrowed a U24XL USB audio interface to do some measurements. I know, it's not an AP, but if it is really bad, I will see it was the idea.

So I connected the output of the V-DAC to the U24XL and I played a 1KHz tone from spotify. The results were shocking. More interesting, if I play a 1KHz tone from youtube, all seems fine!

I checked if I was not clipping the U24XL, but it wasn't. Turning down the volume did not changed the the relative strength of the harmonics. The youtube tone is quiter, but I can put it to the 0dBr before seeing clipping issues.

I used " Audiolab - Audio Test Tones" and " Pure Tone 1000 Hertz - Signal" on spotify and both gave the same results.

Does someone know why spotify seems to perform so badly? Shocking is, I enjoyed it all that time, wondering if I am just used to it or if there's going something wrong with my measurements . .

Edit: I now listened to my normal setup and I can clearly hear spotify distort where youtube don't (with the test tones) Also streaming through my chromecast dongle instead of using the spotify app on my tv give the same result . . .
 

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ThatM1key

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I have mixed experiences using TV's for music.

If you got an Android TV, you can install "USB Audio Player Pro" and use your USB DAC directly. For PCM audio it was golden with my Topping D10, but for DSD, it wouldn't work.

In terms of general music apps, there usually a bad experience. Spotify and SiriusXM have no quality options and most likely use the lowest quality setting. One theory I do have is because TV users generally don't care about quality, they want just to hit play and enjoy the music. So why put the audio quality setting to max and waste bandwidth when most TV users couldn't tell the difference between a MFSL CD and a 20th Century Masters CD. Is it ****** for companies to not let users fiddle with settings? Yes it is because if a TV can handle 4K video, it can handle streaming compressed music.

There is a few Spotify Connect streamers on the market, but there overpriced. There is Chromecast streamers that do Spotify at a lower bitrate but are much cheaper.
 

McFly

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DAC is clipping on first picture.

Something causing TV Spotify to go above 0dbfs would be my guess

LGs when using digital audio outs force stereo signals to 5.1, my Spotify app via HDMI is always 5.1 no matter what I do. That is likely the cause of the problem. Using Spotify connect directly to my AVR sounds much better than the TV app
 

Cars-N-Cans

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I have used TVs as streamers, and on my Sony the toslink/PCM stereo was initially an issue as it would audibly clip. If you can, try to see if your TV has a setting to reduce the output level of the optical out. That will buy some headroom to prevent clipping with some sources. Other than that, even though its not SOTA performance, it should be good enough to be reasonably transparent.
 

Cars-N-Cans

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Does someone know why spotify seems to perform so badly? Shocking is, I enjoyed it all that time, wondering if I am just used to it or if there's going something wrong with my measurements . .
As far as subjective quality goes, its only an issue if the optical clips. My experience was that about 98% of the time, it was fine. But other source material I could audibly hear it clipping. Fortunately on my TV the output level could be set independently, and it's volume disabled so the amplifier's own volume controls could be used instead without the fear of overloading the TV's output.
 

Snoopy

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I never understood why someone would use a TV as music streamer. There are plenty of cheap options out there that are better, smaller and consume so much less power.

On top of that a TV resamples everything to 48khz
 

Rednaxela

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Not sure if it interests you but I do it partly because I like the visual experience that comes with it.

Another reason for me is that the TV is already there and hooked up.

The resampling is a fact but that it would be problematic is not. Edit: at least not that I know. Happy to learn otherwise though.

Agree about the power consumption.
 
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Jimbob54

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DAC is clipping on first picture.

Something causing TV Spotify to go above 0dbfs would be my guess

LGs when using digital audio outs force stereo signals to 5.1, my Spotify app via HDMI is always 5.1 no matter what I do. That is likely the cause of the problem. Using Spotify connect directly to my AVR sounds much better than the TV app
If the TV Spotify app has a volume levelling option, engaging that might sort the OP clipping issue maybe?
 

ZolaIII

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Why not give a try to the DAC in the AVR? I didn't look but it's probably old Burr Brown (Ti). Limit the output to PCM only on TV side. It's possible AVR does ADC part rather bad (and does it anyway on analog input).
Edit: Spotify on mobile platforms at least has EBU R128 implementation but I don't know regarding your TV app so if present give it a try anyway.
 

Katji

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I never understood why someone would use a TV as music streamer. There are plenty of cheap options out there that are better, smaller and consume so much less power.

On top of that a TV resamples everything to 48khz
How can it be hard to understand - especially when it's an expensive LG ''smart'' TV? ...it comes with music streaming app/s, so why should the consumer be expected to understand that it is somehow inferior?
 

mdsimon2

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I think you've touched on a few issues here.

1) Spotify uses lossy compression, you won't get a clean FFT with lossy compression. To be honest both FFTs look like they are starting from a lossy compressed file.
2) At least on Amazon Music HD I've seen surprising variability in test tones. Some with lots of distortion, some with lossy compression even when they are specified as CD quality. I imagine Spotify has similar issues. In particular I remember the Audiolab test tones are not CD quality. This post has a file on Amazon that retains 16 bit fidelity -> https://www.audiosciencereview.com/...amilladsp-tutorial.29656/page-16#post-1150450, maybe it is also on Spotify.
3) As mentioned previously the first example is clipping. That may the result of the source file itself (see 2) or it could be the result of resampling in the TV leading to clipping (see 4).
4) TVs often have very bad resampling. My Vizio won't even retain 16 bit fidelity, see here for more info -> https://www.audiosciencereview.com/...d-path-for-tvs-optical-out.24076/#post-811823.

In order to get a better understanding of what is going on I would start from a known good HDMI source. When I was testing this stuff I was able to use a MacBook Pro HDMI output and REW. This way you know if it is Spotify or your TV or combination of both.

Michael
 

McFly

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I think I'm going to start testing TV digital outputs more often. Audiophiles aside, there will be millions if not tens of millions of people using there TV's as the main source for music via inbuilt aps.

One problem I often run into is the TV assuming any device connected to its digital audio outputs (that is toslink AND HDMI) is 5.1(or higher) capable. What are lowly stereo DACs doing with that information? I notice vocals are always heavily recessed (quiter) when the TV sends 5.1 to a stereo DAC.
 

Sokel

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You can use this to measure without the need of using external signal to measure them as single units.
 
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3cx15000a7

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Thanks for all the replies!

@ThatM1key
But if you have a premium account, does the app on the tv not automatically select the higher quality?

@McFly
Sadly there isn't a volume control when using optical (pcm). It just locks the volume control on the tv and outputs full volume.

@Rednaxela
I actually tried it first with the optical output of the tv directly in the u24xl. I saw the same problem so I thought it was the DAC inside the U24XL so I tried it with the VDac and the analog input of the U24XL

@Zolall
I don't think the VDac causes this problem as I also measured the problem without(see above). If I am right, the Marantz bypass the ADC/digital part using source direct

@mdsimon2
I tested the audiolab file on spotify with my laptop, on the webplayer I don't hear the distortion the app on the tv makes

Also I don't have any device that can extract audio from HDMI, thats the reason I use optical. The receiver don't support ARC
 
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3cx15000a7

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But that DAC isn’t in the chain at all is it?
True! Indeed, my mistake!

@Zolalll, I will try! But what makes you think that DAC inside the receiver doesn't give the bad the results? I also connected the optical out of the tv directly to the optical in of the U24XL (so no vdac and no receiver in the chain) and it was bad too
 

ZolaIII

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True! Indeed, my mistake!

@Zolalll, I will try! But what makes you think that DAC inside the receiver doesn't give the bad the results? I also connected the optical out of the tv directly to the optical in of the U24XL (so no vdac and no receiver in the chain) and it was bad too
It's integrated DAC and I doubt they messed up that one. Symply you will be sure and can exclude ADC suspicions if you feed in directly digital signal from TV.
 

ThatM1key

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@ThatM1key
But if you have a premium account, does the app on the tv not automatically select the higher quality?
It's hard to tell. The Spotify app on my phone, I can select my TV but it says nothing about it being Chromecast and Spotify Connect. Theoretically it could be higher quality if you manually selected with a smartphone but considering it doesn't tell me if its Chromecast and Spotify Connect, I assume its always low quality.
 
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