PBeyer, nicely put & I agree with everything you said up to your hypothesis - I believe & it's been stated before, that some jitter, once added is difficult to remove without sonic penalty (& can it be removed completely anyway?), so why add it in the first instance - I speak particularly of close-in phase noise for instance.
So I would disagree with your last statement - this is a bit like the negative feedback argument in amplifiers where it is assumed that NFB can remove most distortion BUT there are sonic penalties for this. And the best designers say to remove as much distortion as possible before applying a SMALL amount of NFB!
So I would disagree with your last statement - this is a bit like the negative feedback argument in amplifiers where it is assumed that NFB can remove most distortion BUT there are sonic penalties for this. And the best designers say to remove as much distortion as possible before applying a SMALL amount of NFB!
@jkeny
>I believe & it's been stated before, that some jitter, once added is difficult to remove without sonic penalty (& can it be removed completely anyway
so what that suggests is that the timing information is embedded in the ones and zero's? Can you explain?
>this is a bit like the negative feedback argument in amplifiers
No doesn't compare imho. Contrast to analogue, digital = create once copy anywhere. The contra example applies to the digital domain: copies can sound better than originals.
It's all about fixing the time domain problem.
>I believe & it's been stated before, that some jitter, once added is difficult to remove without sonic penalty (& can it be removed completely anyway
so what that suggests is that the timing information is embedded in the ones and zero's? Can you explain?
>this is a bit like the negative feedback argument in amplifiers
No doesn't compare imho. Contrast to analogue, digital = create once copy anywhere. The contra example applies to the digital domain: copies can sound better than originals.
It's all about fixing the time domain problem.
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You said it already - drive mechanics can introduce jitter with their random current demands on the PS. Smaller & simpler would seem to be a way to make solving this issue a bit easier - so solid state might be one possible approach.
I'm talking about NFB as a lazy way of trying to remove excess distortion that shouldn't have been there anyway - so-called Jitter reduction mechanisms are also a lazy way of removing excess time-domain distortion that shouldn't be there in the first place - this is good design, IMO.
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I attached a picture that visualizes the problems introduced by both jitter and interference.
The picture shows a bird, and its distorted reflection in water. From the reflection we can recognize its a bird, but it lacks details when comparing it with the original. With music reproduction we can tell it's a violin, piano, or guitar, but we can't hear what brand it is because details that are unique for every instrument are distorted by interference.
The very best audiophile digital audio playback systems would produce sound quality that could be compared with the reflected image on this picture. They would fail to reproduce details like the eye of the bird for example, simply because of unwanted disturbances in the actual audio signal.
The ripples in the water cannot be removed after they have occurred, if we want a perfect reflection we would have to prevent ripples from occurring in the first place.
It only takes very small ripples in the water in order to distort the reflected image, similar applies to digital audio playback. Thats why I mentioned that we need a digital audio source with zero jitter and zero interference, otherwise sound does get distorted for sure, similar as the reflected image in the example. Once this distortion (time / amplitude) has occurred we basically face similar problems as with the ripples in the water.
The memory card playback systems have the potential (based on their concept) to prevent these "ripples" from occurring.
Attachments
@JKENY
"As we all know jitter can't be completely eliminated only minimised"
Why is that? Do you have a pointer that explains it?
@ecdesign
Nice, though metaphores are difficult to explain the facts.
Don't get me wrong, I too see memory card as a superior device. And you're doign a fantastic job with your project. I only question if it will help us to improve the sound quality. The reason for my post is that I have a pretty high quality digital playback system. Always looking for better, I was thinking about a card player . . . but I am in doubt wheter it will help me.
Question: how do we get music jitter free in a memory card?
One other thing I am puzzled with:
"Oh yes, jitter is by far not the only problem with digital audio playback, interference (source, mains, EM, and so on) that will inter-modulate with the audio spectrum may even cause more perceived sound quality degradation than jitter does."
Doesn't that all just result in jitter? Jitter has manny sources . . . .
"As we all know jitter can't be completely eliminated only minimised"
Why is that? Do you have a pointer that explains it?
@ecdesign
Nice, though metaphores are difficult to explain the facts.
Don't get me wrong, I too see memory card as a superior device. And you're doign a fantastic job with your project. I only question if it will help us to improve the sound quality. The reason for my post is that I have a pretty high quality digital playback system. Always looking for better, I was thinking about a card player . . . but I am in doubt wheter it will help me.
Question: how do we get music jitter free in a memory card?
One other thing I am puzzled with:
"Oh yes, jitter is by far not the only problem with digital audio playback, interference (source, mains, EM, and so on) that will inter-modulate with the audio spectrum may even cause more perceived sound quality degradation than jitter does."
Doesn't that all just result in jitter? Jitter has manny sources . . . .
@ Steerpike
Good point! Hollistic view of the chain is necessary.
Theoretically the only important step there is the A to D conversion. Jitter introduced there is transitive i.e. propagated throughout the whole chain. (it becomes the single verison of the truth so to speak - or the 'new' original if you like) It should be possible to remove jitter introduced after the A to D conversion and get back the 'new' orginal.
So if both CD and memory card suffer from A to D introduced jitter and we know there is not a data transfer problem, what do we (fundamentally!) gain from a memory card?
Very fundamental: How do we get music jitter free in a memory card?
Good point! Hollistic view of the chain is necessary.
Theoretically the only important step there is the A to D conversion. Jitter introduced there is transitive i.e. propagated throughout the whole chain. (it becomes the single verison of the truth so to speak - or the 'new' original if you like) It should be possible to remove jitter introduced after the A to D conversion and get back the 'new' orginal.
So if both CD and memory card suffer from A to D introduced jitter and we know there is not a data transfer problem, what do we (fundamentally!) gain from a memory card?
Very fundamental: How do we get music jitter free in a memory card?
Pbeyer, you seemed to understand in your earlier statements that a well implemented memory card playback system has the potential for lower jitter because of it's lack of moving parts & simpler PS current requirements - now you're asking questions that seem to suggest that you don't understand how a memory card system can be of benefit
- I'm confused - can you clarify?
Jitter and recording:
JVC XRCD has a rubidium clock: http://www.xrcd.com/tech/img/24diaglam.gif.
North American company selling a rubidium word clock for studio synchronization: Antelope Audio
Okay, not so many options.
JVC XRCD has a rubidium clock: http://www.xrcd.com/tech/img/24diaglam.gif.
North American company selling a rubidium word clock for studio synchronization: Antelope Audio
Okay, not so many options.
But you can introduce jitter in the playback system - CD playback being more prone than SD because of all the moving mechanical system playing havoc with the PS
Agreed!
@jkeny
"But you can introduce jitter in the playback system - CD playback being more prone than SD because of all the moving mechanical system playing havoc with the PS"
We have discussed this and agreed upon this.
Re-read my very first entry. Asume good player, I2S, reclocking in DAC, etcera
How can the card player be better in the final result? We use the same source (with intrinsic jitter). Probably copied on a computer etc. Will that make a better copy? Read the posts from Steerpike who said it very well. And #30 "cd is as error proof as any disc based system can be."
Like said before, the trick is in the playback. To be more specific in the D to A conversion. The concept of a memory player doesn't add there. We all basicllay read from memory in a DAC that reclocks the data.
"But you can introduce jitter in the playback system - CD playback being more prone than SD because of all the moving mechanical system playing havoc with the PS"
We have discussed this and agreed upon this.
Re-read my very first entry. Asume good player, I2S, reclocking in DAC, etcera
How can the card player be better in the final result? We use the same source (with intrinsic jitter). Probably copied on a computer etc. Will that make a better copy? Read the posts from Steerpike who said it very well. And #30 "cd is as error proof as any disc based system can be."
Like said before, the trick is in the playback. To be more specific in the D to A conversion. The concept of a memory player doesn't add there. We all basicllay read from memory in a DAC that reclocks the data.
I am not questioning Johns (EC-Designs) player or the SD-card player approach in terms of soundquality. I had a chance to listen to it some weeks ago. 
At these levels IMO specs of clocks doesn't really matter anymore. John is talking femto seconds. Come on - This will be hard to prove anyhow - I bet you - if 10 people measure the same equipment we'll see 10 different results.
What IMO matters is the interference with the rest of the "system", which will degrade your ultra low jitter clock substantially. With external masterclocks as used in professional systems you'll never achieve that level - if call it Rubydium, Kryptonite clock or whatever you call them.
I am not aware of any other player, where such a precise clock is in
sync with the data processing part and the DA conversion at the same time without the need of some sound degrading "nasty workarounds".
The interferences are kept to the absolute minimum.
No idea how you want to beat that approach.
And yes. For sure the recordings itself will be the bottleneck here. It's time that the music recording industry catches up with this - even though I believe they won't. The obvious trend is to go higher samplerates instead of addressing the clock/jitter issues first.
At these levels IMO specs of clocks doesn't really matter anymore. John is talking femto seconds. Come on - This will be hard to prove anyhow - I bet you - if 10 people measure the same equipment we'll see 10 different results.
What IMO matters is the interference with the rest of the "system", which will degrade your ultra low jitter clock substantially. With external masterclocks as used in professional systems you'll never achieve that level - if call it Rubydium, Kryptonite clock or whatever you call them.
I am not aware of any other player, where such a precise clock is in
sync with the data processing part and the DA conversion at the same time without the need of some sound degrading "nasty workarounds".
The interferences are kept to the absolute minimum.
No idea how you want to beat that approach.
And yes. For sure the recordings itself will be the bottleneck here. It's time that the music recording industry catches up with this - even though I believe they won't. The obvious trend is to go higher samplerates instead of addressing the clock/jitter issues first.
If you have the clock inside the DAC and reclock the signals, it doesn't matter anymore what't playing havoc inside the player.
The timing is determined by the clock / reclocker and not whatever may happen inside the CD Player or the SPDIF or receiver chip.
Another thing:
It has been mentioned that CD Rom drives reed sectors up to 80 or howmany times.
That also doesn't matter, a good drive is a good drive and a bad drive is a bad drive.
If the bad drive can't read it on the first attempt, for 99% it also won't do it the second or third or how many times it tries.
Really...
What is the jitter added by a - let me guess - 74LVQ574 or similar flipflop alone ?
I bet not less than 10 - 15 ps.
I think I explained why CDROM drives that read at any speed beyond 1x HAVE to make multiple passes - if playing 'live'. It isn't primarily to make them more accurate, it's because they read data too fast for it to be used. They then have to go into idle mode, and when they wake up from idle mode they cannot immediately resume pickup from where they left off (CD-audio discs do not have explicit sector boundaries as do CD-data discs). They need to make multiple passes of the approximate sector boundaries and reassemble the sectors in RAM.
High-speed drives generally cannot operate at 1x even if that's all you require. They do the fast-read-then-go-idle thing over & over. This is true of many PC-industry-sourced transports used in hi-fi and DVD players.
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