A perfect DAC?

docvale

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Mar 21, 2011
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The big success of computer-based audio systems made DACs some of the most fashionable pieces of gear now. Some of them display an impressive plasticity in connectivity, but, to my knowledge, there's no DAC that has an HDMI input to accept signal streamed by hi-rez players such as the new Oppos.

Don't you think that, together with computer interfaces such as USB and FW, a DAC accepting digital signal from SACDs, DVD-As and BRs through HDMI would be the new center for digital entertainment?
 

NorthStar

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Feb 8, 2011
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Personally, I find HDMI to be an inferior connection with mediocre sound quality!

* I much prefer multichannel analog XLR Balanced or RCA Unbalanced connections.

** And for regular Stereo CDs, I prefer analog (XLR or RCA) Stereo or digital Coaxial connections.
 

amirm

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I think it is fair to say that a DAC should have HDMI whether a user chooses to use it or not. The Daviialet is the only audio-only box I know that has it but they also bundle an amp with it.

To make HDMI addition a non-issue, it should have a way to completely shut it down when not in use.
 

docvale

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Mar 21, 2011
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Personally, I find HDMI to be an inferior connection with mediocre sound quality!

* I much prefer multichannel analog XLR Balanced or RCA Unbalanced connections.

** And for regular Stereo CDs, I prefer analog (XLR or RCA) Stereo or digital Coaxial connections.

Actually I've never had the chance to compare digital connections, so I don't have any opinion on their sound quality. My concern is simply derived by the fact that the expansion of the use of DAC would imply an improved versatility of the machine itself. Whether it is true that you can connect a computer to a DAC even when the DAC doesn't have any USB or FW port, interfacing a consumer -level universal player (such as an Oppo or a Cambridge) with a hi-end DAC is still an issue. I've learnt about some interfaces that get A/V HDMI signal and output video through HDMI (to go to the TV) and audio through Toslink, but this is something that could be bettered.
Now that the newest players have audio-only HDMI outputs, the sound quality of a consumer player could be improved if a DAC could accept a stream through HDMI!

Amir, do you think that the HDMI port would somehow interfere with the other ports? Actually I don't know how it works...
 

DonH50

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Jun 22, 2010
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Bits are bits, except when they aren't. They aren't when they are used in the analog path, and that happens in digital audio when the clock recovered from the bit stream is used to clock the DAC. In most implementations, HDMI has higher jitter than other digital audio links (HDMI is a video link, actually, in the sense that it was a pretty video-centric design). Thus, reclocking is more critical to good sound in an HDMI link.

Amir can (and will, I hope) answer for himself, but anytime you have a wideband digital circuit running there is the potential for noise coupling into the analog stages. Thus, turning off the HDMI link when not being used is a good idea.

I suspect HDMI ports are not on DACs because they cost money to add and the demand is not there yet. Most people getting DACs are using them for stereo sources, e.g. their iPods or streaming digital audio. As video streaming becomes more commonplace I suspect we will see more, and better, multichannel DAC components with HDMI inputs. Seems like an untapped market, though without all the processing for video and digital audio standards like DTS etc. a fairly limited one. To use a HDMI DAC, for many systems there must be components with multiple HDMI outputs (one for the DAC, one for the AVR/video and sound processor), or the DAC must be able to pass through the HDMI signal from e.g. a BD player. More parts, more money.
 

Bruce B

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I think the perfect DAC/Interface will be to use 1 cable for every known sample rate/bit-depth. That interface is MADI. A single coax or optical cable for up to 8 channels of everything. This would have to be DAD AX24
 

docvale

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Mar 21, 2011
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anytime you have a wideband digital circuit running there is the potential for noise coupling into the analog stages. Thus, turning off the HDMI link when not being used is a good idea.

Ok, now I get the point.

As video streaming becomes more commonplace I suspect we will see more, and better, multichannel DAC components with HDMI inputs.

Probably.
I have to say that the idea of perfect DAC that I pictured was not really devoted to A/V entertainment: I'd rather have a 2ch DAC that allowed me to bring to an audiophile level the quality of music on a SACD or a BR. Obviously, many people would like to have this quality repeated on 6+ channels, and that would clearly affect the costs a lot...
 

docvale

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Mar 21, 2011
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I think the perfect DAC/Interface will be to use 1 cable for every known sample rate/bit-depth.

True. Actually, all my DAC-philosophy :))) come out with the post-RedBook digital music (SACD at first), that arrived with a castration of standard digital outputs and proprietary connections (when available, see Accuphase for example). A universal connection, for every digital standard and sampling frequency, would simplify the things!
 

amirm

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The WYRED4SOUND DAC-2 and PS Audio PWD both have HDMI inputs. These HDMI inputs are designed not for accepting HDMI data, but instead are utilized in a PS Audio designed standard for I2S data.
I am familiar with both but as you say, they use HDMI *connector* but otherwise, have no relationship with HDMI as an interface. The signalling over that HDMI connector is an IC interconnect called I2S designed originally by Philips. A big difference is that with true HDMI, audio is slave to video. You must always have a video signal in order to have audio. I2S is a simple data communication bus and the clock is a simple multiple of the audio frequency itself.
 

docvale

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Mar 21, 2011
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A big difference is that with true HDMI, audio is slave to video. You must always have a video signal in order to have audio.

Does it apply to the newest Oppo 93 and 95 and the top-of-line Denon, which have dedicated dual HDMI outputs? Is there maybe a "black" video signal? If yes, my idea of perfection would be reconsidered...
 

amirm

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Does it apply to the newest Oppo 93 and 95 and the top-of-line Denon, which have dedicated dual HDMI outputs? Is there maybe a "black" video signal? If yes, my idea of perfection would be reconsidered...
Yes, it applies to all HDMI device including the new Oppo. There must be a video signal even if it is blank video. What that means is that video pixels are black but the the system is still scanning all the lines/pixels at high frequency. I don't think the mere fact of having the video pixels be black makes that much of a difference. The big problem still is that audio clock is slave to that high frequency video clock and as such, is subject to degradation.
 

NorthStar

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I am familiar with both but as you say, they use HDMI *connector* but otherwise, have no relationship with HDMI as an interface. The signalling over that HDMI connector is an IC interconnect called I2S designed originally by Philips. A big difference is that with true HDMI, audio is slave to video. You must always have a video signal in order to have audio. I2S is a simple data communication bus and the clock is a simple multiple of the audio frequency itself.

Wow, thanks Amir I didn't know that!

So the same cable carries Video & Audio that have to be on simultaneously in order to operate properly!
...And I've read so much talk about high amount of jitter in the digital HDMI interface!
And I can easily hear the difference at home on what kind of connections sound better.
And HDMI is certainly not it!

_______________________

Furthermore, a separate DAC with more interconnects between it and the source is tough as it has to match that source in the clocking for limited amount of jitter!
As anything else in life as in Audio, separate components have to work together in perfect synchronicity for top performance.

So a 'perfect' DAC requires a 'perfect matching source' or transport!
The electronics in each component have to work in tandem, and the inputs and outputs have to be perfectly matched!

Am I thinking right?
 

docvale

Well-Known Member
Mar 21, 2011
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Briarcliff Manor, NY
Yes, it applies to all HDMI device including the new Oppo. There must be a video signal even if it is blank video. What that means is that video pixels are black but the the system is still scanning all the lines/pixels at high frequency. I don't think the mere fact of having the video pixels be black makes that much of a difference. The big problem still is that audio clock is slave to that high frequency video clock and as such, is subject to degradation.

Well, this changes everything about my idea of a perfect DAC! Is it known how the things will work with the new thunderbolt port (the one just introduced with the newest MacBooks)?
 

docvale

Well-Known Member
Mar 21, 2011
542
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Briarcliff Manor, NY
a separate DAC with more interconnects between it and the source is tough as it has to match that source in the clocking for limited amount of jitter!
As anything else in life as in Audio, separate components have to work together in perfect synchronicity for top performance.

So a 'perfect' DAC requires a 'perfect matching source' or transport!
The electronics in each component have to work in tandem, and the inputs and outputs have to be perfectly matched!

Am I thinking right?

I guess there's nothing wrong in what you're saying... I can only say that the comfort of computer audio is, IMHO, extremely high! :) My current system is really humble (MacBook + HRT Streamer II), but decent in term of value for money. Honestly, for the future, whatever it is in my possible upgrades and gear renewal, I doubt I'll go back to an approach with spinning silver disc*. But, on the other hand, I'd like to have the chance to listen to concert on DVD and BR enjoying the quality of a nice system, so whether there will be some gear that will be truly universal, it will be very appreciated**! :)

*= this is somehow bizarre. I'm really into vinyls and I love the ritual of preparing a disc to be played and seeing it spinning... but I don't care about CDs that much!
**= apparently the new MSB products should match this need (a universal transport that can be matched with a state-of-the-art DAC that is capable to be connected to a computer), but the transport to DAC connection is proprietary and prices are leveled to the great reputation of the company. It would be great whether other companies would provide gear that adhere to the concept approach of versatility...
 

NorthStar

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Feb 8, 2011
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Every musician is different, they all have their own personality, and nobody play the same musical piece the same.

It is the same with Audiophiles, Music Lovers, Audience at a Concert Hall...
No one listen the exact same, and no one is sitting at the same spot in that Hall.
And at home we all have our own signature sound whether it is from our computers, music servers, turntables, reel-to-reel tape decks, CD players, Unuversal DVD or Blu-ray players, etc., and the room, and the loudpeakers, and how many of them, and EVERYTHING else that is so unique to each one of us and at the same time connects us ALL! :)

The material we listen to and the artists performing it is what we breathe and live!

You know; someone with a great large room and a superb Stereo system, and another one with a great PC and music server sitting at his desk are totally in a different sound space! You simply cannot compare!

I learned something new here on this thread; and it's about HDMI audio that cannot operate with the Video portion still active even if there are no picture!

*** The best improvement that you can make in your system, much better than upgrading your interconnects, is to get rid of all the cables that you don't need!
 

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