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Old 15th December 2010, 09:26 AM   #1031
WDYSUN is offline WDYSUN  Italy
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Default Spdif

Hello Buddies,

just because somebody is talking about measurements vs subjective feelings, may I ask whether it has been compared the Buffalo Spdif input with the S/PDIF Transceiver Module? any noticeable difference?

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Old 15th December 2010, 02:22 PM   #1032
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Will sound/measure better by I2S rather than direct spdif?
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Old 15th December 2010, 02:55 PM   #1033
labjr is offline labjr  United States
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Originally Posted by regiregi22 View Post
Will sound/measure better by I2S rather than direct spdif?
I hope so.
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Old 15th December 2010, 03:48 PM   #1034
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There seems to be a fundamental misunderstanding about the way the ES9018 handles SPDIF.

Where SPDIF has its issues is when SPDIF receivers have to obtain their clock from the SPDIF signal. The ES9018 does not do this at all. The SPDIF data is input completely asynchronously, it is not merely re-clocked, it is never generating a clock in the first place.

The truth is both I2S and SPDIF input measure exactly the same. That is because in the end they are treated exactly same. The only difference is what the DAC does to load up the data queue.

Because there is no clock recovery involved, there is really no penalty to using SPDIF except that you are limited to 24bit input where I2S can do 32bit. Just like anything else though, if the signal input is junk, the output will be too. So you still have to have good source.
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Old 15th December 2010, 03:49 PM   #1035
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Originally Posted by regiregi22 View Post
Will sound/measure better by I2S rather than direct spdif?
Speculatively: this will likely depend. Are you questioning if it would be better to use a separate SPDIF receiver and then feed the B-II I2S from that? The SPDIF receiver onboard the ESS 9018 is a pretty sophisticated and unique design (at least from what I can read in the public domain documentation)-I would not be surprised to find that the ESS 9018 SPDIF receiver actually outperforms other options (like the standard Crystal receiver).
Now if the I2S is generated not from SPDIF, but from, say, Russ' forthcoming asynchronous USB receiver, that will be another matter. The async USB to I2S should have an advantage, because the data is never subjected to the clock embedded format of SPDIF, and the necessary clock recovery circuitry (which adds jitter). Additionally, these points may be somewaht moot, due to the ESS' onboard "jitter rejection" via the ASRC, but in reality I doubt it-My B-II certainly sounds different when fed from different sources, so, as usual, less jitter in results in better sound out. Interestingly, one B-II owner has reported on the TPA forums, that the B-II does sound better when fed I2S from a Hiface Evo asynchronous USB interface versus SPDIF from the same source.
Could these differences be measured? Sure, but proper measurements of jitter are very complex, and require very specialized gear. Very few people have the gear to really measure jitter differences.

Last edited by barrows; 15th December 2010 at 03:53 PM. Reason: added details...
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Old 15th December 2010, 04:15 PM   #1036
labjr is offline labjr  United States
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Originally Posted by Russ White View Post
There seems to be a fundamental misunderstanding about the way the ES9018 handles SPDIF.

Where SPDIF has its issues is when SPDIF receivers have to obtain their clock from the SPDIF signal. The ES9018 does not do this at all. The SPDIF data is input completely asynchronously, it is not merely re-clocked, it is never generating a clock in the first place.

The truth is both I2S and SPDIF input measure exactly the same. That is because in the end they are treated exactly same. The only difference is what the DAC does to load up the data queue.

Because there is no clock recovery involved, there is really no penalty to using SPDIF except that you are limited to 24bit input where I2S can do 32bit. Just like anything else though, if the signal input is junk, the output will be too. So you still have to have good source.
The S/PDIF still has a clock even if they strip it off. And the data keeps flowing so they need to somehow delay this and reclock it into the DAC. The only way would seem to be with a PLL or whatever they want to call it now. Since they can't stop or change data flow. S/PDIF doesn't work that way.

Thus, to me sounds like ASRC in a roundabout way. Albeit with a different approach.
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Old 15th December 2010, 05:02 PM   #1037
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It has the ability to generate a clock yes, but it is *only* that generated clock that is ill and in the case of the ESS DAC it is not used at all. In any way.

SPDIF does not even really "have a clock", but you can derive a clock from it. That is the heart of the issue where standard receivers are used.

No clock extraction (which usually requires some type of PLL) is done at all in the case of ESS method.

The data is just data which is queued, and gets stuffed into a buffer. Much the same way that asynchronous USB works.

SPDIF once you are not running through a PLL to obtain a clock is just like any other 1 wire protocol.
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Last edited by Russ White; 15th December 2010 at 05:07 PM.
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Old 15th December 2010, 05:20 PM   #1038
glt is offline glt  United States
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I just rigged my Musiland to output I2S last night. So far, both SPDIF and I2S sounds the same.

In my crude setup, so far spdif seems to be a "more solid" signal compared to I2S. With SPDIF I can use lowest dpll bandwidth setting in BuffaloII and with I2S I get drop-outs unless I increase the bandwidth of the DPLL. Russ suspects is noise in the I2S lines. The wires I am using are only 3 inches long.
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Old 15th December 2010, 05:28 PM   #1039
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Then the noise is likely not from your wiring. More likely from the source.

The DPLL is really finicky about phase noise. You can widen the DPLL window but then you are passing in some of that phase noise down stream.
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Old 15th December 2010, 06:55 PM   #1040
LeonvB is offline LeonvB  Netherlands
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I have no argument with what you are hearing. And I have no intent on building a dual mono B-II, as this approach is just philosophically not the way I like to do things.
On the Tridents though, I have a set of these for my new Legato II/B-II build, and I certainly expect them to offer a sonic improvement-no reason why a lower noise/impedance power supply, and the elimination of (due to no need) of electrolytic caps should not result in sonic benefits. In fact, my experience is that power supply changes often offer the biggest improvements in performance for any audio components.
Well I can certainly relate to what you state there. I've doubted for about 2 years about building the (then Buffalo) DAC. Going dual mono is also something I had great doubts about, not for philosophical reasons but because it requires one to simply buy about twice the hardware for a tiny bit of extra performance. And I only started building the DAC as I wanted a DIY companion to my balanced power amp, with good volume control. It has become a slightly bigger project than anticipated...

For me however the end result is all that matters. And I'm more than satisfied with the result, however it's achieved. The modular nature of the new DAC board allows for an almost infinite freedom to mix and match as one sees fit. And I would certainly recommend going for the Tridents well before going dual mono. It's simply a much more afffordable improvement, and one I'd like to see as an integral part of the BIII board if one ever is going to be designed.
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