Thread: This equipment good enough for SACD?

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Post by Iain January 12, 2015 (121 of 128)
zeus said:

The DBT-3313UD is simply a transport. It reads the disc and sends the data over the HDMI connection. It still receives firmware updates to ensure compatibility with current discs. For network support (e.g. DSD streaming) Denon have been more properly adding such functionality to the receiver.

Duly noted. I'm quite impressed with the gapless playback of my AVR. It must be a one-off, because I can't think of any other AVR that that offers this feature.

Now, if they could only get multi-channel playback sorted.

Post by Ad Rhenum January 12, 2015 (122 of 128)
zeus said:

Denon Link HD is coax. While Denon doesn't go into much detail on the latest iteration, a cursory explanation of the previous version is here:

http://www.denon.com/pages/GlossaryDetail.aspx?GId=14

Really though it's the whole-of-system results that count, something IMHO best left to the ears.

Quote from the link:

"DENON LINK 4th uses the master clock in the A/V surround receiver as the reference for controlling the video circuitry and the disc drive in the player, and the digital video and audio signals from Blu-ray disc are transmitted to the A/V surround receiver via an HDMI cable."

This quote suggests the clock of the player is slaved to the clock of a/v receiver. Theoretically the player should be data transporter only (over denon link 4th) and have no influence on the sound. But I might have missed something, or things are more complicated.

So, just listen, I agree.

Post by Fitzcaraldo215 January 13, 2015 (123 of 128)
Ad Rhenum said:

Quote from the link:

"DENON LINK 4th uses the master clock in the A/V surround receiver as the reference for controlling the video circuitry and the disc drive in the player, and the digital video and audio signals from Blu-ray disc are transmitted to the A/V surround receiver via an HDMI cable."

This quote suggests the clock of the player is slaved to the clock of a/v receiver. Theoretically the player should be data transporter only (over denon link 4th) and have no influence on the sound. But I might have missed something, or things are more complicated.

So, just listen, I agree.

One quibble to your statement: in general, if the connection is asynchronous, there is no "slaving" of the player master clock to the processor or DAC master clock. That applies only to fully synchronous transmission, like methods incorporating I2S. But, it is also not completely clear from Denon's description whether it is truly asynchronous or not. I think we are all in agreement in any case that (a.) Denon has given the interconnection issue a great deal of thought for quite some time, and (b.) it really should be judged ultimately by listening to the result.

Post by Ad Rhenum January 15, 2015 (124 of 128)
Master/slave is a model of communication where one device or process has unidirectional control over one or more other devices. (source:wikipedia)

With a synchronous connection the process to be controlled is timing. With asynchronous connection the process to be controlled is data transfer. Synchronous playback is about controlling the timing of the clock in the external da-converter. Asynchronous playback is about controlling the in- and outflow of data in the buffer of the da-converter.

The only way to controll data transfer from an optical disc reader is to adjust it's speed of reading. The speed of reading a disc is controlled by a clock. So, to perform asynchronous playback, you will have to control the clock of the disc reader. Synchronizing the player clock to the clock in the external da-converter would be a vulnerable design. It might result in data arriving at the wrong time in the da-converter. Thus, at the right time the wrong data might be converted.

The accuracy of the of the clock in the dac is not about average timing. The clock must define the exact moment of conversion. The conversion is done in steps. Wich means the timing of individual steps must be identical, or as identcial as possible. To visualize the effect, think of riding a brick road. The street as a whole might be level, but when individual bricks are not level, or not level with the surrounding bricks, you get a bumpy ride. When individual bricks are level and level with the surrounding bricks, you get a smooth ride, even if the street as a whole is not completely level.
https://www.youtube.com/watch?v=yoKqnBJN8iQ

I found some jitter measurement on the effect of Denon Link 4th and Sony Hats. Note that the author also thinks Denon Link is asynchronous ("the audio clock isn't being carried from the transport to the DAC over HDMI"). For as far I know, you can do audio playback from an external device only do as synchronous, or as asynchronous. Also I have found no indication Denon Link 4th is not ascynchronous
https://www.avforums.com/threads/denons-dvd-a1ud-universal-sacd-dvd-a-dvd-cd-blu-ray-player.877651/page-25#post-10199775

Both, hirez and multichannel are more demanding on the accuracy of the clock. Inaccuracy of the clock can be somewhat compensated by the use of other, usually more expensive, components in the da-converter. Which might explain why the quality of hirez and multichannel is difficult to hear on low-budget da-converters.

Post by zeus January 15, 2015 (125 of 128)
Ad Rhenum said:

I found some jitter measurement on the effect of Denon Link 4th and Sony Hats. Note that the author also thinks Denon Link is asynchronous ("the audio clock isn't being carried from the transport to the DAC over HDMI"). For as far I know, you can do audio playback from an external device only do as synchronous, or as asynchronous. Also I have found no indication Denon Link 4th is not ascynchronous
https://www.avforums.com/threads/denons-dvd-a1ud-universal-sacd-dvd-a-dvd-cd-blu-ray-player.877651/page-25#post-10199775

I'm not surprised by these figures. When I evaluated the Oppo BDP-103 into my NAD M51 DAC (one of the few DACs that supports HDMI input) coax output was clearly superior to HDMI. As I was planning on using HDMI exclusively I sent the Oppo back. However high levels of jitter inherent to HDMI don't tell the full story as the DAC/receiver/preprocessor can correct this somewhat by buffering the data and reclocking. Denon mentions issues with video and multichannel due in part to the large amount of data that has to be buffered. Maybe other manufacturers figure they don't have to fix the HDMI stream at source as buffers can just be made larger. My feeling is that it doesn't hurt to do both. Certainly the Denon combo is an impressive sounding piece of kit. And with future audio developments moving more to the network and implemented on the receiver end with open standards there's less need for the source to be a do-everything device ... which has been Oppo's strength to date.

Post by Ad Rhenum January 23, 2015 (126 of 128)
I've been looking a bit closer into Denon link. The purpose of Denon link was to transmit uncompressed high resolution music data from player to external reciever. And playback asynchronous with the player to reduce jitter. There is an elucidating illustration from Denon (see above).

The way Denon link 1 till 3rd works is comparable. The red audio data line and the yellow control data line are both on the Denon link rj45 ethernet cable. The same for HATS from Sony. For these two you can replace cd with dvd-audio or sa-cd. Also data over asynchronous USB and ethernet like DNLA work the same, both red line and yellow line are the usb or ethernet cable. But instead of a cd the data will be derived from a buffer or hard disc, and there will be no audio circuit, but a data circuit.

The difference between Denon 1 till 3rd is that the initial Denon link could only transmit non-copy protected music data. In 2003 Denon received permission from the dvd-consortium to transmit uncompressed copy protected dvd-audio data, so now Denon link second edition could transmit all cd and dvd-audio. In may 2005 Denon link was approved by Sony and Philips for tranmission of sa-cd.

Post by Ad Rhenum January 23, 2015 (127 of 128)
So, it looks as if getting permission for transmitting copy protected data was more an issue than technical issues, such as size of the data memory. And copy protection for blu-ray discs is even more complex then for dvd or sa-cd, and tranmission probably only limited to hdmi and direct connection of transmitter and receiver. Which possibly will not allow a data memory in between. My guess is, it's not the amount of data that forced Denon to delete the data memory for transmission of hd-content, but the restrictions of transmission for copy protected data.

In fact the Denon link 4th, or Denon link hd (in the latter the ethernet connection is replaced by a coax connection) is a variant of the conventional jitter suppression technology: The yellow correction data connection is perfected by transmitting the clock data, which results in a near perfect timing of the data stream. Wich can be handled in the small buffer that the audio circuit of the receiver will have. The result is also, that audio output and video output remain synchronized.
So, I think the main reason for deleting the audio data memory is not the size of the data, but copy protection issues.

Which raises new questions: if dsd downloads in the future will be copy protected, can they be played back in present da-converters?

Post by Fitzcaraldo215 January 24, 2015 (128 of 128)
Ad Rhenum said:

...

Which raises new questions: if dsd downloads in the future will be copy protected, can they be played back in present da-converters?

Interesting stuff on Denon Link.

I doubt that DSD downloads in the future will be any more copy protected than they are today, which is completely unprotected. DSD DACS now are not prepared for copy protection, unlike SACD players or some AVRs and prepros. Imposing copy protection would cause major incompatibility issues and likely kill the DSD download business.

The solution to the copy protection issue for Internet sources is streaming rather than downloading. As it stands now, streams cannot be copied (unless that is hacked in future). But, streaming presents its own technical challenges, particularly with hi rez and its high bandwidth requirements.

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