XDS1/CD/SACD Player

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JackD201

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Apr 20, 2010
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All i know is 16/44.1 data is "upconverted" to twice the dsd sampling rate as opposed to the usual pcm upsampling. Analog stage uses all discrete devices and there's supposed to be only 1 gain stage from from the d/a stage to the analog outputs. I also read somewhere that it uses the highest model of the TEAC VOSP drive, which is a notch below the VRDS transport used in the more expensive Esoteric units.

Jack, AVDI claims to have sold 3 or 4 units na daw. Does your transport use the VRDS transport?

My Emms? No the Philips I think that keeps on crapping out on me. The EERA uses their own transport called the Gyropoint. All the OEM tray does is bring the disc in then the disc is picked up by the mechanism and clamped to a carbide ball thingy. Rather Rube Goldberg-esque but it works. :)
 

NorthStar

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Frank, still, there is an interaction with the preamp stage.

Also, I know of no products with zero jitter.

* But it don't really matter at the end; what truly counts is what's delivered to your ears. :)
Still though, I am always looking for the best implementation in any digital gear;
and distortion figures, jitter figures, and all other measurements all add up at the end.

Also, very good point by Dafos just above; the transport, very important piece of the overall result (sound quality, faithfulness).
A good tracking ability is directly related to a good isolated transport free of mechanical perturbances and outside disturbances.

I have great respect for Ed Meitner from EMM Labs. He is one of the true explorators in DACs and their implementation.
And I love the build quality of DCS gear.
Esoteric, great stuff too with great value.

I love dual differential balanced DACs (four of them per channel, well chosen and equal in their most precise specifications). ...I'm a sucker for DACs.
I also love high sampling, upsampling frequency range extention (352kHz). Garbage out way up there!
And high bit rate (32-bit).
And I love digital inputs, so you can take advantage of these high resolution techs in a product.

If you want my 25 grands and up (read $80,000+), you'd better give me what I consider to be not only state-of-the-art sound, parts, features, practicality, enjoyment, velours enrapturing (emotional state), but also state-of-the-art future proofing with all the enchilada that comes with it! :)
 
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fas42

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Frank, still, there is an interaction with the preamp stage.

Also, I know of no products with zero jitter.
What sort of interaction do you mean, Bob? If the only thing that connects to the preamp is the audio out of the DAC then there should be no interference. Now, I do believe there is interference in typical cases, because power supplies aren't perfect, and RF noise can be mixed in with the audio signal being fed to the preamp, because the engineering is not up to scratch. But jitter can be reduced to levels below what is theoretically audible by using a good enough crystal in a single box, it's when you have transport and separate DAC that the nightmares begin ...

If you want my 25 grands and up (read $80,000+), you'd better give me what I consider to be not only state-of-the-art sound, parts, features, practicality, enjoyment, velours enrapturing (emotional state), but also state-of-the-art future proofing with all the enchilada that comes with it! :)
I'll settle for SOTA sound, which automatically includes "velours enrapturing", the rest is just trimming ... :)

Frank
 

Rupunzell

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Dec 26, 2010
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Sorry, reducing jitter is NOT this simple. Try designing a "zero jitter clock" and prove it to the scientific and engineering community with hard data and experiments that can be reproduced by others. Crystals come in many, many varies. Each has their individual personality. None have zero jitter. Zero jitter also implies zero noise which implies zero atomic motion.. see where this is headed...?

If zero jitter was so easy to achieve, this should be the standard on every digital device, but this has not become reality.

Having designed more than one very, very low jitter system.. it is way more difficult than one might ever imagine.. Design concept is only one aspect, the building and testing of the circuit and system grows in difficulty in a very non-linear way.

Keep in mind, light travels about a foot oer nanosecond in free space. One nanosecond is an order of magnitude greater than what is tolerable for digital audio.



Bob, some people may dispute this, but a one box player should have zero jitter problems if properly engineered. You simply place a crystal oscillator with as low phase noise as you want, directly translates to low jitter, right next to the DAC chip or circuitry and that controls all the clocking throughout the player. An incompetent engineer can still get it wrong, but it should be as straightforward as that.

Frank
 

fas42

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Sorry, reducing jitter is NOT this simple. Try designing a "zero jitter clock" and prove it to the scientific and engineering community with hard data and experiments that can be reproduced by others. Crystals come in many, many varies. Each has their individual personality. None have zero jitter. Zero jitter also implies zero noise which implies zero atomic motion.. see where this is headed...?
Rupunzell, I didn't say zero jitter, I said zero jitter problems: of course there will always be some phase noise, but it is not that hard to get crystals with jitter below the noise level of digital. Of course, if you have to recover a stable clock from a data stream then that is a whole different issue ...

Frank
 

NorthStar

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Frank,

The interaction I meant is multiple; with the voltage output from the internal preamp stage in the player, the various power supplies, and also through the other various circuits, including the signal paths, the material used in the circuit board, and in the outside transmission cable as well,
and finally in the separate preamp component itself. And more...

The crystal quartz clock oscillator by itself is not the last bastion of jitter.
 

fas42

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The crystal quartz clock oscillator by itself is not the last bastion of jitter.
I think we may have a misunderstanding of what jitter is: from my understanding this is noise or distortion, call it what you like, which is superimposed on the audio signal because the the translation from digital to audio is not done at the precise moment in time that it should be. The clock wherever it comes from, from a crystal or by regenerating from a data stream, is going tick, tick, tick, and at every tick or certain precise number of ticks something happens in the DAC circuitry. Now if each successive tick is not falling at the exact same fraction of a second after the previous one, measured in pico seconds, a millionth millionth of a second accuracy then you get jitter, the clock is wobbling -- same thing as flutter in a turntable as far as the audio signal is concerned, except at extremely high speed.

Off the top of my head you need around 120 pico secs accuracy, better than that and it makes no difference. The only place where this is important is in the DAC area, into here you feed the clock and the stream of data from the digital filter, which is fed from the CD say. If you have the extremely precise crystal clock, the digital filter and DAC all next to each other, and the clock controls exactly when the DAC sees the digital filter data, then you have complete control of jitter. Of course the DAC may be a bit imprecise and other circuitry may be affected by interference, but that's not the same as jitter problems ...

Frank
 
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