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Discussion Starter #1
I’ll try to make this as succinct as possible. I’m trying to determine whether my TV is passing Dolby Digital 5.1 to the theater system through the optical cable after receiving it from HDMI inputs. According to what I can find online, my TV (Samsung 51E450 plasma) is NOT supposed to be able to pass DD through the optical output unless the TV itself is acting as the tuner… so it shouldn’t work for HDMI inputs. I even emailed Samsung, and they told me the same thing. But I think it actually IS passing it through.

Here’s why I think that. If the HDMI source is not sending a DD signal to the TV (either because it is naturally stereo, or because I intentionally set it up to not send DD), then the Dolby Digital option in the TV’s Audio Output settings menu is grayed out. But when the HDMI source is sending a DD signal, that option is no longer grayed out on the TV. And when I select it, the audio changes -- so it definitely does something different than PCM. If DD output were not possible, I don’t see why it would be an option – certainly not one which accurately senses when there is a DD input to pass along.

To test this out more thoroughly, I set up my theater system to NOT use Pro Logic II when it has only a stereo input – that is, I set it up to output stereo (rather than synthetic 5.1) when its input is stereo. Then on the TV, I selected PCM (stereo) as the audio output. As I expected, this resulted in audio only from the front left and front right speakers – nothing from center, rear, or subwoofer. Then I changed the TV’s output to Dolby Digital without changing any settings on the theater system, and I immediately got audio from all six speakers.

So my question is this: is there any other way I’d be getting audio from all six speakers if the theater system wasn’t receiving DD 5.1? Remember, I had Pro Logic II turned off, so the theater system was simply outputting whatever it was receiving. Unfortunately, my theater system will not report to me what type of signal it is receiving, so I'm left to my own tests to figure that out. I just want to verify that I'm interpreting the test result accurately and not overlooking some other possibility.
 

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Using a A/V calibration disc may help. Something like the old Video Essentials. IIRC it has audio setup and calibration material.
 

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Out of interest... What is your 'HDMI source' device?
 

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I’ll try to make this as succinct as possible. I’m trying to determine whether my TV is passing Dolby Digital 5.1 to the theater system through the optical cable after receiving it from HDMI inputs. According to what I can find online, my TV (Samsung 51E450 plasma) is NOT supposed to be able to pass DD through the optical output unless the TV itself is acting as the tuner… so it shouldn’t work for HDMI inputs. I even emailed Samsung, and they told me the same thing. But I think it actually IS passing it through.
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that is doubtful...and I have never seena samsung Tv that would output dolby digtial from a source other than the TV's tuner

whats does your AVR/prepro say the signal is?

what brand of AVR/prepro do you have.?

Onkyo's for instance have an all channel stereo mode

Warren
 

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Discussion Starter #7
Couldn't you run the optical cable to the receiver directly?
No, because I have multiple sources but my receiver only has one optical input. And the Roku only outputs HDMI anyway.

The reason I'm trying to figure this out, though, is that if I determine that the TV is not outputting DD, then I can buy an HDMI switch and just run the audio cable from that to the receiver, bypassing the TV altogether.

that is doubtful...and I have never seena samsung Tv that would output dolby digtial from a source other than the TV's tuner
Yeah, that is consistent with everything I've been able to find online. But I can't reconcile that with what is actually happening on my TV.

whats does your AVR/prepro say the signal is?
what brand of AVR/prepro do you have.?
The receiver is a Panasonic SC-BTT190. It's a combination blu-ray player and theater system. Probably low-end compared to what most folks on a forum like this would have, but for me it's been great. A giant step up from the TV's speakers, yet still within my budget.

It does not report what the signal is, which is why I'm having to figure that out myself.

Onkyo's for instance have an all channel stereo mode.
Yeah, mine has Pro Logic II, which takes a stereo input and simulates a DD 5.1 output. I made sure to turn that off for my test. And when I did, the receiver only put out stereo -- nothing on the other speakers. So I know Pro Logic II was successfully disabled. Then I switched the TV to Dolby Digital, and that's when sound began coming out of the other speakers. So the difference is definitely in the TV setting, not the receiver.

What I'm trying to determine is whether there is something else the TV could be sending besides DD 5.1 which the receiver would interpret as a six-channel signal.
 

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No, because I have multiple sources but my receiver only has one optical input. And the Roku only outputs HDMI anyway.

The reason I'm trying to figure this out, though, is that if I determine that the TV is not outputting DD, then I can buy an HDMI switch and just run the audio cable from that to the receiver, bypassing the TV altogether.


Yeah, that is consistent with everything I've been able to find online. But I can't reconcile that with what is actually happening on my TV.



The receiver is a Panasonic SC-BTT190. It's a combination blu-ray player and theater system. Probably low-end compared to what most folks on a forum like this would have, but for me it's been great. A giant step up from the TV's speakers, yet still within my budget.

It does not report what the signal is, which is why I'm having to figure that out myself.


Yeah, mine has Pro Logic II, which takes a stereo input and simulates a DD 5.1 output. I made sure to turn that off for my test. And when I did, the receiver only put out stereo -- nothing on the other speakers. So I know Pro Logic II was successfully disabled. Then I switched the TV to Dolby Digital, and that's when sound began coming out of the other speakers. So the difference is definitely in the TV setting, not the receiver.

What I'm trying to determine is whether there is something else the TV could be sending besides DD 5.1 which the receiver would interpret as a six-channel signal.
sounds like a optical cable switcher could become your best friend....to give you some added input capability

Warren
 

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Discussion Starter #9
sounds like a optical cable switcher could become your best friend....to give you some added input capability
Warren
Either that or an HDMI switch with an optical output. But I don't want to spend the money on that if it's not going to give me anything more than I currently have.

So I keep coming back to the question: how else is the receiver getting six channels of audio if the TV isn't sending DD 5.1?
 

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Either that or an HDMI switch with an optical output. But I don't want to spend the money on that if it's not going to give me anything more than I currently have.

So I keep coming back to the question: how else is the receiver getting six channels of audio if the TV isn't sending DD 5.1?
I really doubt you are receiving DD 5.1 from your TV

a switch is less than $20

Warren
 

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Discussion Starter #11
I really doubt you are receiving DD 5.1 from your TV
So what would it be? Is there something between stereo and full-fledged DD 5.1?
I'm not trying to be argumentative. I just don't know enough about audio, so I'm trying to find out what it is, not just what it probably isn't.

a switch is less than $20
One with optical output is about $45... just a little beyond what I'm willing to fork out without knowing it'll improve anything.
 

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So what would it be? Is there something between stereo and full-fledged DD 5.1?
I'm not trying to be argumentative. I just don't know enough about audio, so I'm trying to find out what it is, not just what it probably isn't.


One with optical output is about $45... just a little beyond what I'm willing to fork out without knowing it'll improve anything.
I suspect its some type of all channel stereo mode

an optical only switch is less than $10

an HDMI to optical switch is about $26

check Ebay

Warren
 

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Think Warren may be right could be all channel stereo. You would be getting sound from all speakers, just not 5.1. Can you position yourself between say the front right and rear right speakers? You should hear the same thing from each if all stereo. You shouldn't hear the same thing if it's 5.1.
 

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Based on what you've said and the TV's manual, I would say you are getting 5.1 audio. Your TV has a setting specifically for the SPDIF output which isn't restricted to DTV only, and depends upon the audio format of the source. This setting and the manual's description would make no sense unless the TV was designed to pass 5.1 audio through the toslink.
 

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Discussion Starter #15
Think Warren may be right could be all channel stereo. You would be getting sound from all speakers, just not 5.1.
But I have it set to not do that. And when the TV is set to PCM out, the only speakers with any audio are the front left and front right. It only starts outputting audio through the other speakers when I change the TV setting to Dolby Digital.

Can you position yourself between say the front right and rear right speakers? You should hear the same thing from each if all stereo. You shouldn't hear the same thing if it's 5.1.
The rear audio is definitely different from the front.
 

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Discussion Starter #16 (Edited)
Based on what you've said and the TV's manual, I would say you are getting 5.1 audio. Your TV has a setting specifically for the SPDIF output which isn't restricted to DTV only, and depends upon the audio format of the source. This setting and the manual's description would make no sense unless the TV was designed to pass 5.1 audio through the toslink.
Yes, that's what I understand the manual to be saying also, although I will say it wasn't explicit. It didn't say it would, but it didn't say it wouldn't either. Since the Dolby Digital output option is grayed out (visible on screen but not selectable) when there is no DD signal being sent from the source but IS selectable when there is a DD signal being sent from the source, it seems logical to me that it is indeed an option. And the option I'm referring to is specifically for optical out, not for the built-in speakers.

The only reason I started doubting it is that everything I've read online indicates that Samsung TVs do not have this capability. So I emailed Samsung tech support, and they told me the TV does not output DD via optical out unless the TV was acting as the tuner... so not when the source is HDMI.

Thus my confusion...


  • Supporting the idea that the TV will pass DD from HDMI to optical:
    • the manual (albeit not explicitly)
    • my own tests (which I'm still looking for another explanation)
  • Supporting the idea that the TV will NOT pass DD from HDMI to optical:
    • online references
    • Samsung tech support

I know it's not the receiver changing the audio to multi-channel; whatever is happening, it's happening in the TV. And I haven't yet heard a plausible explanation for how the receiver could be receiving a multi-channel input which is not DD 5.1.
 

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Discussion Starter #17 (Edited)
For reference, here's what is in the TV user manual:

The SPDIF (Sony Philips Digital InterFace) outputs an uncompressed digital audio signal when you connect the digital audio jack on the back of the TV to a digital audio in jack on a receiver or home theater.

  • Audio Format (PCM/Dolby Digital): You can select the Digital Audio output (SPDIF) format. The available Digital Audio output format may differ depending on the input source.
  • By connecting the TV to a receiver or home theater with Dolby Digital and 5.1ch speakers and selecting Dolby Digital, you can maximize your interactive 3D sound experience.

The part I put in bold could be interpreted two different ways. But I would think that if it were as simple as "Dolby Digital is only available when the TV is the tuner" they would have put it that way. The openness of the way it reads leads me to believe DD is an option for other types of inputs as well, provided they are sending a DD signal. Having said that, I've also found the manual to be a bit vague in other places also, so it wouldn't really surprise me either way in this instance.
 

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For reference, here's what is in the TV user manual:

The SPDIF (Sony Philips Digital InterFace) outputs an uncompressed digital audio signal when you connect the digital audio jack on the back of the TV to a digital audio in jack on a receiver or home theater.

  • Audio Format (PCM/Dolby Digital): You can select the Digital Audio output (SPDIF) format. The available Digital Audio output format may differ depending on the input source.
  • By connecting the TV to a receiver or home theater with Dolby Digital and 5.1ch speakers and selecting Dolby Digital, you can maximize your interactive 3D sound experience.

The part I put in bold could be interpreted two different ways. But I would think that if it were as simple as "Dolby Digital is only available when the TV is the tuner" they would have put it that way. The openness of the way it reads leads me to believe DD is an option for other types of inputs as well, provided they are sending a DD signal. Having said that, I've also found the manual to be a bit vague in other places also, so it wouldn't really surprise me either way in this instance.
Dolby is compressed audio, so their manual seems to contradict itself.

What I had read was p. 53 of this manual. Note that it specifically mentions DVD players and that, unlike other parts of manual's audio section, does not limit the setting to digital tv channels (ie the tuner) :

http://downloadcenter.samsung.com/content/UM/201203/20120307195644278/X9DVBEU4E-ENG.pdf
 

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Discussion Starter #19
Dolby is compressed audio, so their manual seems to contradict itself.
I hadn't caught that before. Maybe it just means the TV doesn't add its own compression, or that the compression is less lossy than what you would get from an RCA stereo connection.

What I had read was p. 53 of this manual. Note that it specifically mentions DVD players and that, unlike other parts of manual's audio section, does not limit the setting to digital tv channels (ie the tuner) :
http://downloadcenter.samsung.com/content/UM/201203/20120307195644278/X9DVBEU4E-ENG.pdf
That's for a different TV than mine. Do manufacturers tend to do the same thing (with respect to this conversation) with all TV models?
 
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