Why not use HDMI to access the AVR's internal DAC chipset before PRE/PWR amplification?

[kyoto]

New to the forums, not sure if this has been discussed, but can't found anything via the search.

 

I just bought an Apple TV, and knowing the limitations of the Toslink and the disabled USB. Was thinking if I used the HDMI output to my Yamaha Z11 AVR (top of the range decoding chipset for AVR), then "processor" pre-out to my ARC Pre amp and MBL Poweramp. Would that be as good as buying a separate DAC for the ATV (was thinking about BADA or others).

 

 

 

 

[CharlyD]

I could find no specification for the maximum sample rate/word length for WAV, AIFF or ALAC files on the digitial outputs by the Apple TV. I did find that the audio chip used in the Apple TV, the Realtek ALC 885, can support S/PDIF output up to 24/192. I found another post (from Chris) on this site indicating it is his understanding that Apple TV will up/down convert all audio to 16/44.1. There is no reason I know of why the architecture you suggest shouldn't work. Have you tried the HDMI hookup to your A/V receiver with redbook files (16/44.1)?

 

[Mr.C]

Yes, it will work.

 

"Would that be as good as buying a separate DAC for the ATV (was thinking about BADA or others)."

 

Unless you have an AVR that has as much attention paid to its DAC section as the BADA or whichever dac, it probably won't sound as good. It all comes down to quality of engineering and components. AVRs have a lot of stuff that they have to be good at and they usually aren't excellent at any one thing. It's the combination that creates the AVR magic. Also, I think HDMI has more jitter than other formats because it has a less frequent frame rate or something like that.

 

[kyoto]

thanks for the comment: That's really the question that got me going. Since I was listening to a Bluray Concert with my AVR, and the same coming out of it was amazingly beautiful, with great detail and open soundstage. I mean my Yamaha Z11 has the best audio DAC chipset within the entire Yamaha range of audio components, and that decoding is the "heart" of what AVRs do. Hence, the among of dedication the AVR devotes to the DAC process cannot be just "get it done" material right?

 

As for the large jitter associated with HDMI. I am wondering if HDMI format is not as good comparing to Toslink or USB for audio output, then why would PS Audio use this particular format for there newest Perfect-wave transport + DAC?

Quote from PS Audio below: "I2S through HDMI output"

"Instead of trying to stuff these clocks and data into one stream, I2S simply transfers the three clocks and the data on separate cables to the DAC. Done in this way, there's no chance for error or increased jitter and the audible results are simply stunning."

"The best solution we found was HDMI (High Definition Multi-media Interface) . An HDMI cable is the best multi-conductor digital cable made today and it was the obvious choice for the PWT."

"Simply use any HDMI cable between the PWT and the PWD and you are transferring data perfectly. "

 

[kyoto]

Thanks for the comment:

If this is the case. I am wondering if anyone on this forum or elsewhere you have heard of that's able to "hack" the ATV into bypassing the "down conversion" during output? This will be the biggest one single hack for the CA community as ATV will be the most convenient and cheapest Transport alternative around.

 

[CharlyD]

When playing your BlueRay concert on your AVR, I'm assuming that the only connection between the player and AVR is HDMI. In this case, the Dolby or DTS data is being transferred over HDMI to the AVR and being decoded there. In the case of playing an audio file encoded in WAV or AIFF audio, the conversion to LPCM is happening in the ATV. If one of these scenarios sounds audibly better than the other, one of the implemenations could be improved. I suspect that with direct LPCM input to your receiver, there is no buffering and the sample clock is derived from the data stream whereas with DD or DTS data, there is buffering and the sample clock is local to the DAC.

 

PS Audio uses only the HDMI cable for their I2S connection, not the HDMI protocol.

 

[kyoto]

So, PS Audio uses only the HDMI cable for their I2S connection, not the HDMI protocol. Is that where the JItter issues come on with the HDMI format? I am a newbie in this and would love to discuss it with any expert.

 

If for example, I'm able to hack the ATV and install Boxee onto it. Does that mean the USB is now usable for audio output into external USB DACs? If HDMI is compromised, then how about the DAC chipset via USB of the AVR?

 

I am only asking since these are questions on my mind which I have no answer to.

 

[One and a half]

DTS-Master for example for BD is encoded at 24bit/192kHz max. Standard music of 16/44.1 would always sound pedestrian in comparison. Since te audio industry bickers about sampling rates and which codec to choose, the movies have bypassed that and made some very good codecs (DTS-Master, Dolby True). At least there are now some standards!!!

 

"Since I was listening to a Bluray Concert with my AVR, and the same coming out of it was amazingly beautiful, with great detail and open soundstage"

Yes, you will get this on BD, because most modern movies are encoded at this quality with the dynamic range to boot. There are a handful of BD music releases out now encoded from the ground up.

 

Pumping through 24bit audio hi rez files through the HDMI interface in computers is totally dependant on how good the VIDEO card is, the audio card just "supplies" the signal to the video card. The Video card with a HDMI output connector overlays the audio and video together down the HDMI pipe to the AVR as this is how HDMI works. Audio and video aren't separate channels, it's a multiplex system if you like and complex encoding at that. Google for a presentation from Thomas Kite, Director of Engineering, Audio Precision Beaverton, OR. He explains how HDMI 1.3 audio works and jitter is nipped in the bud by selecting the right components. Low jitter components are found in Pioneer BD players, but I have yet to see video card manufacturers quouting low figures for their jitter.

 

[kyoto]

Back to the original topic. Will HDMI take over as the medium for HD audio output even for stereo in the short future?

 

Seems like the AVR is already at the front line of this change. Shouldn't it be a matter of time before the "jitter" issue is solved with software or hardware and that any media streamer with HDMI output will be able to link with a HDMI DAC for 24/192 HD audio?

 

My ATV will arrive in the next couple of days. I'll run it thru the Yamaha Z11 and then to the ARC Ref3 Preamp via processor input before my MBL power amps and Verity Audio Fidelio Encore speakers. Will update on the comparison against my MBL 1531 CD player when I've done some listening test.

 

I'll most likely head to the showroom to test out the BADA. If I like what I hear, then it's going to be the receiver for both my MBL Transport (AES) and ATV (Toslink).

 

 

 

[CharlyD]

Will HDMI take over as the medium for HD audio output even for stereo in the short future?

Already has. USB and S/PDIF as communication protocols for HD Audio will never gain the traction in the marketplace already enjoyed by HDMI. I'm assuming the entire consumer electronics market here; not just the tiny market of hi-end audio.

 

The very good presentation on HDMI audio by Thomas Kite of Audio Precision (http://www.aessf.org/meetings/presentations/AESSF_HDMI_Audio_Presentation.ppt) cites implementations of an HDMI audio interface by Silicon Image in which "Injecting even high levels of jitter into the source audio clock produced no measurable jitter at the receiver".

 

What's still missing is a good bridge between HD audio files on a PC/Mac/Server and the HDMI input on an A/V Receiver or Processor. The ATV won't fill that bill until it supports transfer of greater than red book over HDMI.

 

[kyoto]

thanks for the comment CharlyD.

 

Though I still think theres a long way till HDMI could really say it's taken over the stereo arena. For one, could you name any audiophile grade Stereo DACs on the market that's got HDMI input? Even the PS Audio PWD converts the HDMI cable into I2S format instead of the HDMI protocol. At this moment, only AVRs have HDMI into into their internal DACs. Thus, we're no where close to "domination" of the Audiophile community into utilizing HDMI cables for both Computer nor CD enjoyment. Just my 2 cents.

 

Given said all that, I will get my Apple TV this week, and hopefully also the BADA. Thinking of getting a AQ Toslink cable to go between the 2. Then I am planning to order a AES cable from Purenote for my MBL 1531 output into the BADA. Lets hope 2010 will be the year Apple takes out the down conversion of the ATV or some bright young hacker figure out how to do it for them !

 

[CharlyD]

A/V processors by Classe, Mark Levinson, Anthem, Rotel, NAD, Classe, Marantz, Lexicon and probably several others I'm not recalling. All these A/V processors have outstanding analog sections with DACs capable of rendering hi-res audio content. Of course, none of these are limited to only 2 channel stereo. This dichotomy in the technologies applied to 2-channel systems vs. A/V systems makes no sense, and I'm sure market pressures will determine the survivors. The hi-end, 2-channel market is already very tiny.

 

[kyoto]

Finally took the plunge and bought a Berkeley Audio Alpha DAC last night. The ATV will arrive in mail today, and I've got both the AES and Toslink cable ready to play. The only downside obviously is the downconversion of the ATV to red book standard. Lets hope some break thru in hacking comes along shortly and we'll have unrestricted bit rate information coming out of the tiny streamer soon. Will update on sound soon !

 

 

[tennisarm]

Hi kyoto,

 

just stumbled over this discussion and wonder how the setup finally sounded? Thanks for sharing the experience!

 

Cheers,

tennisarm