Jitter and CD-R

[Guest]

Archived from groups: rec.audio.high-end (More info?)

Orange book specification for CD-R states the followings:-

1. Jitter (depending on writing device) <35ns

2. Under the quality parameters - Jitter is a "measurement" of quality of
the recorded data. the lower the value, the higher the quality and the
better the player can read the disc.

Does this mean that the disc itself contain jitter and some CD-R can have
jitter less than 35ns. And if that is the case, is it possible that
different disc to sound differently?

Cheers.

 

[ban]

Archived from groups: rec.audio.high-end (More info?)

Chelvam wrote:
> Orange book specification for CD-R states the followings:-
>
> 1. Jitter (depending on writing device) <35ns
>
> 2. Under the quality parameters - Jitter is a "measurement" of
> quality of the recorded data. the lower the value, the higher the
> quality and the better the player can read the disc.
>
> Does this mean that the disc itself contain jitter and some CD-R can
> have jitter less than 35ns. And if that is the case, is it possible
> that different disc to sound differently?

Our ears can perceive jitter if it lies above a certain level. For deep
tones(200Hz) it is 500ns, but for higher frequencies we are more sensitive
to it, 1ns at 15kHz.
Luckily the loop filters of the PLL also attenuate more at the higher
frequencies, so a single number for low frequencies will give a comparison
between different chips.
The new S/PDIF receivers of Texas Instruments achieve a max. jitter of
0.8ns, those of Cirrus around 3ns. Both values are far below audibility.
These front end ICs are not expensive and almost all AV-receivers use them.

The recording usually had been with very little jitter, because a very
stable quartz generator is used (jitter<0.05ns).
The CD-player or receiver has to generate the clock signal from the received
data rate, which is controlled by speeding the drive motor more or less.

It is like distortion, below 0.1% it is no more audible, we cannot hear a
difference if it is 0.001% or 0.1%. But if a couple of components each
contribute 0.1%, the values are added squared and the root of the sum gives
the result. So if cd-player, preamp, power amp and loudspeaker each have
0.1% THD, the result is 0.2% which is audible. In reality the loudspeakers
might have 0.5% and dominates. The values of the other components are so
much lower (0.01%) that they do not matter at all.
--
ciao Ban
Bordighera, Italy

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

On 6/21/04 6:20 PM, in article cb7mvu0gpt@news3.newsguy.com, "Ban"
<bansuri@web.de> wrote:

> It is like distortion, below 0.1% it is no more audible, we cannot hear a
> difference if it is 0.001% or 0.1%. But if a couple of components each
> contribute 0.1%, the values are added squared and the root of the sum gives
> the result. So if cd-player, preamp, power amp and loudspeaker each have
> 0.1% THD, the result is 0.2% which is audible. In reality the loudspeakers
> might have 0.5% and dominates. The values of the other components are so
> much lower (0.01%) that they do not matter at all.

Except with a CD player 0.1%, Preamp 0.1%, amp 0.1%, and speaker 0.5% -
almost half of the distortion would be those components - so if you were to
reduce them - and the total distortion would be audible - wouldn't it sound
better?

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

On 21 Jun 2004 22:20:46 GMT, "Ban" <bansuri@web.de> wrote:

>Chelvam wrote:
>> Orange book specification for CD-R states the followings:-
>>
>> 1. Jitter (depending on writing device) <35ns
>>
>> 2. Under the quality parameters - Jitter is a "measurement" of
>> quality of the recorded data. the lower the value, the higher the
>> quality and the better the player can read the disc.
>>
>> Does this mean that the disc itself contain jitter and some CD-R can
>> have jitter less than 35ns. And if that is the case, is it possible
>> that different disc to sound differently?
>
>Our ears can perceive jitter if it lies above a certain level. For deep
>tones(200Hz) it is 500ns, but for higher frequencies we are more sensitive
>to it, 1ns at 15kHz.
>Luckily the loop filters of the PLL also attenuate more at the higher
>frequencies, so a single number for low frequencies will give a comparison
>between different chips.
>The new S/PDIF receivers of Texas Instruments achieve a max. jitter of
>0.8ns, those of Cirrus around 3ns. Both values are far below audibility.
>These front end ICs are not expensive and almost all AV-receivers use them.
>
>The recording usually had been with very little jitter, because a very
>stable quartz generator is used (jitter<0.05ns).
>The CD-player or receiver has to generate the clock signal from the received
>data rate, which is controlled by speeding the drive motor more or less.
>
>It is like distortion, below 0.1% it is no more audible, we cannot hear a
>difference if it is 0.001% or 0.1%. But if a couple of components each
>contribute 0.1%, the values are added squared and the root of the sum gives
>the result. So if cd-player, preamp, power amp and loudspeaker each have
>0.1% THD, the result is 0.2% which is audible. In reality the loudspeakers
>might have 0.5% and dominates. The values of the other components are so
>much lower (0.01%) that they do not matter at all.

There are two different jitters involved here; they are totally
different things, and have different effects.

The jitter that may - or may not - change the quality of the sound in
a digital system is that present at the D/A conversion point. It is
present across a complete word of data, and is very easily dealt with
- and has been in every implementation you will encounter today.

The second type of jitter is that which you find in the receiver that
pulls individual bits of a CD. The only thing that this can do is
occasionally cause a bit to be read wrongly - a zero for a one.
Provided this jitter is not too serious, these errors are always
corrected. None (and I do mean none ) of this jitter finds its way
through the audio chain.

d
Pearce Consulting
http://www.pearce.uk.com

 

[ban]

Archived from groups: rec.audio.high-end (More info?)

Bromo wrote:
> On 6/21/04 6:20 PM, in article cb7mvu0gpt@news3.newsguy.com, "Ban"
> <bansuri@web.de> wrote:
>
>> It is like distortion, below 0.1% it is no more audible, we cannot
>> hear a difference if it is 0.001% or 0.1%. But if a couple of
>> components each contribute 0.1%, the values are added squared and
>> the root of the sum gives the result. So if cd-player, preamp, power
>> amp and loudspeaker each have
>> 0.1% THD, the result is 0.2% which is audible. In reality the
>> loudspeakers might have 0.5% and dominates. The values of the other
>> components are so much lower (0.01%) that they do not matter at all.
>
> Except with a CD player 0.1%, Preamp 0.1%, amp 0.1%, and speaker 0.5%
> - almost half of the distortion would be those components - so if you
> were to reduce them - and the total distortion would be audible -
> wouldn't it sound better?

With 0.1% each of the other components and speaker 0.5%, the total would be
0.5291%. With 3x 0.01% and 0.5% resp. total is 0.5003%
We can see the dominating influence of the speaker. Here has been made a lot
of progress, for example the very low distortion of the economically priced
Usher brand. Recommended as a woofer GF10.
--
ciao Ban
Bordighera, Italy

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

Bromo wrote:
> On 6/21/04 6:20 PM, in article cb7mvu0gpt@news3.newsguy.com, "Ban"
> <bansuri@web.de> wrote:
>
>
>>It is like distortion, below 0.1% it is no more audible, we cannot hear a
>>difference if it is 0.001% or 0.1%. But if a couple of components each
>>contribute 0.1%, the values are added squared and the root of the sum gives
>>the result. So if cd-player, preamp, power amp and loudspeaker each have
>>0.1% THD, the result is 0.2% which is audible. In reality the loudspeakers
>>might have 0.5% and dominates. The values of the other components are so
>>much lower (0.01%) that they do not matter at all.
>
>
> Except with a CD player 0.1%, Preamp 0.1%, amp 0.1%, and speaker 0.5% -
> almost half of the distortion would be those components - so if you were to
> reduce them - and the total distortion would be audible - wouldn't it sound
> better?
>
But then a CD player that produces 0.1% distrotion would be bad, to put
it mildly. Normally I see distortion ratings for CD players at 0.00025%,
Integrated amps at 0.009 to 0.01%, and the rest i don't really know. Of
course the speakers would be the greatest distortion contributor by far,
as has been pointed out earlier.

From what I've picked up about jitter, it seems that only the
manufacturing process and the capability of the AD and DA stages are the
main contributors to jitter. Control those and you 've got jitter licked.

CD

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

In article <DxCBc.83003$eu.47855@attbi_s02>,
"Chelvam" <chelvam@myjaring.net> wrote:

> Orange book specification for CD-R states the followings:-
>
> 1. Jitter (depending on writing device) <35ns
>
> 2. Under the quality parameters - Jitter is a "measurement" of quality of
> the recorded data. the lower the value, the higher the quality and the
> better the player can read the disc.
>
> Does this mean that the disc itself contain jitter and some CD-R can have
> jitter less than 35ns. And if that is the case, is it possible that
> different disc to sound differently?

No, it does not mean that the disc itself contains jitter. Jitter is
random deviation from the ideal frequency of a clock. Do you see a
clock generator mounted in CDs?

The Orange Book spec is talking about maximum allowable jitter in the
clock used to modulate the write laser. This affects the physical
length of the simulated pits and lands written to the CD-R. If there is
too much jitter (resulting in too much deviation from the ideal
lengths), readers attempting to play back the disc may experience bit
errors. If the jitter is really bad, the bit error rate will be so bad
that there are uncorrectable errors.

The audible effects are due to incorrect bits, not jitter. There is no
more jitter in the DAC clock when playing such a disc than when playing
any other disc, because the DAC clock is not derived from the disc.

--
Tim

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

"Ban" <bansuri@web.de> wrote in message news:<rJXBc.160051$Ly.72074@attbi_s01>...
> Bromo wrote:
> > On 6/21/04 6:20 PM, in article cb7mvu0gpt@news3.newsguy.com, "Ban"
> > <bansuri@web.de> wrote:
> >
> >> It is like distortion, below 0.1% it is no more audible, we cannot
> >> hear a difference if it is 0.001% or 0.1%. But if a couple of
> >> components each contribute 0.1%, the values are added squared and
> >> the root of the sum gives the result. So if cd-player, preamp, power
> >> amp and loudspeaker each have
> >> 0.1% THD, the result is 0.2% which is audible. In reality the
> >> loudspeakers might have 0.5% and dominates. The values of the other
> >> components are so much lower (0.01%) that they do not matter at all.
> >
> > Except with a CD player 0.1%, Preamp 0.1%, amp 0.1%, and speaker 0.5%
> > - almost half of the distortion would be those components - so if you
> > were to reduce them - and the total distortion would be audible -
> > wouldn't it sound better?
>
> With 0.1% each of the other components and speaker 0.5%, the total would be
> 0.5291%. With 3x 0.01% and 0.5% resp. total is 0.5003%
> We can see the dominating influence of the speaker. Here has been made a lot
> of progress, for example the very low distortion of the economically priced
> Usher brand. Recommended as a woofer GF10.

Hmyy, distortion, normally speakers have over 10% distortion and up to
50%, that's why manufacturers do not usually even tell it. I think I
had something like 5-7% on my nautilus 804, let me check it and get
back to you.

BRGDS
Riku

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

"Timothy A. Seufert" <tas@mindspring.com> wrote in message
news:cbaefk0lu5@news2.newsguy.com...
> In article <DxCBc.83003$eu.47855@attbi_s02>,
> "Chelvam" <chelvam@myjaring.net> wrote:
>
> > Orange book specification for CD-R states the followings:-
> >
> > 1. Jitter (depending on writing device) <35ns
> >
...snip...snip...

> The Orange Book spec is talking about maximum allowable jitter in the
> clock used to modulate the write laser. This affects the physical
> length of the simulated pits and lands written to the CD-R.

35ns of jitter is pretty high, isn't it? I thought the average is about
hundreds of picosecond.

The orange book specs state less than 35ns. Why would Sony want to state
their typical value is 32ns ( a difference of 3ns) and that exceeds the
standard? What different would 3ns make? and why do they need to state that
especially when all these are highly technical documents not meant for
average consumer.

Btw, the other standard stated for
Max pit and land length deviation (3T) (same as jitter) is +-40ns

and

Max pit and land length deviation (11T) (same above) is + - 60ns



Regards.

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

"Ban" <bansuri@web.de> wrote:

>The recording usually had been with very little jitter, because a very
>stable quartz generator is used (jitter<0.05ns).
>The CD-player or receiver has to generate the clock signal from the received
>data rate, which is controlled by speeding the drive motor more or less.

I had to deal with several types of jitter generated by a poor S/P DIF
receiver in my external D/A converter. With the device in its original
state the DIF receiver generated mirror frequencies, clearly audible when
a sine sweep was sent to the D/A converter. After fixing that problem
some remaining jitter sounded like noise _to me_. But I never heard
anything like distortion with that D/A converter.

For testing CDr media I look at the eye diagram at the HF amplifier stage.
Jitter looks different for different dyes and different refective medium.
But I was never able to hear it.

>It is like distortion, below 0.1% it is no more audible, we cannot hear a
>difference if it is 0.001% or 0.1%.

Is jitter always like distortion? How is it perceived?

Norbert

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

"Timothy A. Seufert" <tas@mindspring.com> wrote in message
news:cbaefk0lu5@news2.newsguy.com...

> In article <DxCBc.83003$eu.47855@attbi_s02>,

> "Chelvam" <chelvam@myjaring.net> wrote:

>

>

Snip...snip...



> No, it does not mean that the disc itself contains jitter. Jitter is

> random deviation from the ideal frequency of a clock. Do you see a

> clock generator mounted in CDs?



snip....snip...



>

> The audible effects are due to incorrect bits, not jitter. There is no

> more jitter in the DAC clock when playing such a disc than when playing

> any other disc, because the DAC clock is not derived from the disc.







However, although slight errors in pits length would almost never result in
a different integer value (and would consequently not affect the audio
data), such variations may cause jitters, i.e. variations in data timing.
Such errors are due to the normal tolerances of glass mastering and
injection moulding.





The resulting jitter affects the sound quality, as it blurs the sound
representation and increases the high-frequency noise. Practically, jitter
can make a difference between different discs in a same batch, or can be
noticed while playing the same disc in different players which would present
more or less susceptibility to jitter (here, emphasis has also to be put on
the quality of the laser mechanism which will go from an extrem to the other
while using respectively low-cost or high-end products). The very tight
control on pit length provided by the PSP system actually reduces
pressing-induced jitter by at least a factor two, and potentially much more.
As a result, audio quality, which is definitely affected by the injection
moulding process, can be improved considerably.





These were the words of OEM.

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

guruguru@jippii.fi (Guruguru) wrote:



>
>"Ban" <bansuri@web.de> wrote in message
>news:<rJXBc.160051$Ly.72074@attbi_s01>...
>> Bromo wrote:
>> > On 6/21/04 6:20 PM, in article cb7mvu0gpt@news3.newsguy.com, "Ban"
>> > <bansuri@web.de> wrote:
>> >
>> >> It is like distortion, below 0.1% it is no more audible, we cannot
>> >> hear a difference if it is 0.001% or 0.1%. But if a couple of
>> >> components each contribute 0.1%, the values are added squared and
>> >> the root of the sum gives the result. So if cd-player, preamp, power
>> >> amp and loudspeaker each have
>> >> 0.1% THD, the result is 0.2% which is audible. In reality the
>> >> loudspeakers might have 0.5% and dominates. The values of the other
>> >> components are so much lower (0.01%) that they do not matter at all.
>> >
>> > Except with a CD player 0.1%, Preamp 0.1%, amp 0.1%, and speaker 0.5%
>> > - almost half of the distortion would be those components - so if you
>> > were to reduce them - and the total distortion would be audible -
>> > wouldn't it sound better?
>>
>> With 0.1% each of the other components and speaker 0.5%, the total would be
>> 0.5291%. With 3x 0.01% and 0.5% resp. total is 0.5003%
>> We can see the dominating influence of the speaker. Here has been made a
>lot
>> of progress, for example the very low distortion of the economically priced
>> Usher brand. Recommended as a woofer GF10.
>
>Hmyy, distortion, normally speakers have over 10% distortion and up to
>50%, that's why manufacturers do not usually even tell it. I think I
>had something like 5-7% on my nautilus 804, let me check it and get
>back to you.
>
>BRGDS
>Riku

Oh come on. I've measured hundreds of home and car speakers and none of them
have distortion greater than 10% until they are driven into overload.

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

In article <cbflka0vjn@news2.newsguy.com>,
"Chelvam" <chelvam@myjaring.net> wrote:

> However, although slight errors in pits length would almost never result in
> a different integer value (and would consequently not affect the audio
> data), such variations may cause jitters, i.e. variations in data timing.
> Such errors are due to the normal tolerances of glass mastering and
> injection moulding.
>
> The resulting jitter affects the sound quality, as it blurs the sound
> representation and increases the high-frequency noise.

So let me get this straight: you are arguing that errors in pit lengths
resulting in jitter in the signal read from the disc has audible
effects, even when there are no changes in data values?

If that is truly your position, you don't understand how CD playback
systems work.

> Practically, jitter
> can make a difference between different discs in a same batch, or can be
> noticed while playing the same disc in different players which would present
> more or less susceptibility to jitter (here, emphasis has also to be put on
> the quality of the laser mechanism which will go from an extrem to the other
> while using respectively low-cost or high-end products). The very tight
> control on pit length provided by the PSP system actually reduces
> pressing-induced jitter by at least a factor two, and potentially much more.
> As a result, audio quality, which is definitely affected by the injection
> moulding process, can be improved considerably.
>
> These were the words of OEM.

Oh, you're just parroting somebody else. I googled on PSP system jitter
and found who it was. Looks like a supplier to high end audio
companies, so they're probably just using standard high end meaningless
pseudo-technical patter to promote their products.

--
Tim

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

"Timothy A. Seufert" <tas@mindspring.com> wrote in message
news:cbq7b701kqb@news3.newsguy.com...
> In article <cbflka0vjn@news2.newsguy.com>,
> "Chelvam" <chelvam@myjaring.net> wrote:
>
snip...snip..

> > The resulting jitter affects the sound quality, as it blurs the sound
> > representation and increases the high-frequency noise.
>
> So let me get this straight: you are arguing that errors in pit lengths
> resulting in jitter in the signal read from the disc has audible
> effects, even when there are no changes in data values?

Not me but OEM http://www.daisy-laser.com, they are pretty reputable in
audio industry, aren't they?

> If that is truly your position, you don't understand how CD playback
> systems work.

Never claimed I do. I hear and decide. I hear copies of CD-R sound bit
different from the original. I know digital is digital and supposedly it
should EXACT copy. Experience tell me otherwise. Not only me, there are many
people in recording industry believes so. So I am asking and quoting.

> > Practically, jitter
> > can make a difference between different discs in a same batch, or can be
> > noticed while playing the same disc in different players which would
present
> > more or less susceptibility to jitter ...snip...snippp
>
> > These were the words of OEM.
>
> Oh, you're just parroting somebody else. I googled on PSP system jitter
> and found who it was.

Yes I was parroting the words of OEM.

Looks like a supplier to high end audio
> companies, so they're probably just using standard high end meaningless
> pseudo-technical patter to promote their products.
>

I hope daisy-laser people can reply this. As far as I am concern, I heard
difference in CD-R and original. When I recorded at different speed, i heard
difference. No pops or skips, just different. And I am sharing that with
others.

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

"Timothy A. Seufert" <tas@mindspring.com> wrote in message
news:<cbq7b701kqb@news3.newsguy.com>...
> In article <cbflka0vjn@news2.newsguy.com>,
> "Chelvam" <chelvam@myjaring.net> wrote:
> > However, although slight errors in pits length would almost never
> > result in a different integer value (and would consequently not
> > affect the audio data), such variations may cause jitters, i.e.
> > variations in data timing. Such errors are due to the normal
> > tolerances of glass mastering and injection moulding.
> >
> > The resulting jitter affects the sound quality, as it blurs the
> > sound representation and increases the high-frequency noise.
>
> So let me get this straight: you are arguing that errors in pit
> lengths resulting in jitter in the signal read from the disc has
> audible effects, even when there are no changes in data values?

That is correct. While I wouldn't generalize the audible effect of
jitter as "blurs the sound representation and increases the
high-frequency noise," I had understood that it was generally
accepted that time-base errors in the data read from the disc can
result in measurable changes in the recovered analog signal.

John Atkinson
Editor, Stereophile

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

I am also quoting sony here. Typically another sales puff.

"Chelvam" <chelvam@myjaring.net> wrote in message
news:cbd2rb01k8q@news1.newsguy.com...
> "Timothy A. Seufert" <tas@mindspring.com> wrote in message
> news:cbaefk0lu5@news2.newsguy.com...
> > In article <DxCBc.83003$eu.47855@attbi_s02>,
> > "Chelvam" <chelvam@myjaring.net> wrote:
> >
> > > Orange book specification for CD-R states the followings:-
> > >
> > > 1. Jitter (depending on writing device) <35ns
> > >
> ..snip...snip...
>
> > The Orange Book spec is talking about maximum allowable jitter in the
> > clock used to modulate the write laser. This affects the physical
> > length of the simulated pits and lands written to the CD-R.
>
> 35ns of jitter is pretty high, isn't it? I thought the average is about
> hundreds of picosecond.
>
> The orange book specs state less than 35ns. Why would Sony want to state
> their typical value is 32ns ( a difference of 3ns) and that exceeds the
> standard? What different would 3ns make? and why do they need to state
that
> especially when all these are highly technical documents not meant for
> average consumer.
>
> Btw, the other standard stated for
> Max pit and land length deviation (3T) (same as jitter) is +-40ns
>
> and
>
> Max pit and land length deviation (11T) (same above) is + - 60ns
>
>
>
> Regards.
>

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

"Chelvam" <chelvam@myjaring.net> wrote in message
news:<x%gEc.173343$3x.86251@attbi_s54>...
> "Timothy A. Seufert" <tas@mindspring.com> wrote in message
> news:cbq7b701kqb@news3.newsguy.com...
> > So let me get this straight: you are arguing that errors in pit
> > lengths resulting in jitter in the signal read from the disc has
> > audible effects, even when there are no changes in data values?
>
> Not me but OEM http://www.daisy-laser.com, they are pretty reputable in
> audio industry, aren't they?

As a subsidiary of Philips, I guess they are "pretty reputable." BTW,
if you have a Plexstor Professional CD-R writer, it comes with a utility
called Plextools, which enables you to examine the time-base error on
your CD-Rs, as well as things like BLER (Block Error Rate). Essential
for mastering.

John Atkinson
Editor, Stereophile

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

In article <3KhEc.126350$eu.114636@attbi_s02>,
Stereophile_Editor@Compuserve.com (John Atkinson) wrote:

> "Timothy A. Seufert" <tas@mindspring.com> wrote in message
> news:<cbq7b701kqb@news3.newsguy.com>...
> > In article <cbflka0vjn@news2.newsguy.com>,
> > "Chelvam" <chelvam@myjaring.net> wrote:
> > > However, although slight errors in pits length would almost never
> > > result in a different integer value (and would consequently not
> > > affect the audio data), such variations may cause jitters, i.e.
> > > variations in data timing. Such errors are due to the normal
> > > tolerances of glass mastering and injection moulding.
> > >
> > > The resulting jitter affects the sound quality, as it blurs the
> > > sound representation and increases the high-frequency noise.
> >
> > So let me get this straight: you are arguing that errors in pit
> > lengths resulting in jitter in the signal read from the disc has
> > audible effects, even when there are no changes in data values?
>
> That is correct. While I wouldn't generalize the audible effect of
> jitter as "blurs the sound representation and increases the
> high-frequency noise," I had understood that it was generally
> accepted that time-base errors in the data read from the disc can
> result in measurable changes in the recovered analog signal.

If and only if pit length / position errors cause a sufficiently high
bit error rate in the raw datastream that there are errors in the
recovered sample values after the C1 and C2 error correction algorithms
do their work.

In other words, as long as the bitstream delivered to the DAC is the
same, the recovered analog signal is the same, within the limits of the
DAC. Jitter in the clock used to write a disc cannot propagate to
playback _as_jitter_, for the simple reason that playback uses an
entirely independent clock source.

--
Tim

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

In article <x%gEc.173343$3x.86251@attbi_s54>,
"Chelvam" <chelvam@myjaring.net> wrote:

> "Timothy A. Seufert" <tas@mindspring.com> wrote in message
> news:cbq7b701kqb@news3.newsguy.com...
> > In article <cbflka0vjn@news2.newsguy.com>,
> > "Chelvam" <chelvam@myjaring.net> wrote:
> >
> snip...snip..
>
> > > The resulting jitter affects the sound quality, as it blurs the sound
> > > representation and increases the high-frequency noise.
> >
> > So let me get this straight: you are arguing that errors in pit lengths
> > resulting in jitter in the signal read from the disc has audible
> > effects, even when there are no changes in data values?
>
> Not me but OEM http://www.daisy-laser.com, they are pretty reputable in
> audio industry, aren't they?

I wouldn't know, but claims like that are pretty suspect.

> > If that is truly your position, you don't understand how CD playback
> > systems work.
>
> Never claimed I do. I hear and decide. I hear copies of CD-R sound bit
> different from the original. I know digital is digital and supposedly it
> should EXACT copy. Experience tell me otherwise.

You haven't done, or at least haven't mentioned doing, the things you
need to do in order to turn your experience into something more reliable
than anecdote. For example, just for starters, did you verify that the
copies actually were bit perfect? (And did you do so using the machine
used to validate the differences? -- Because some readers will succeed
at reading a marginal quality disc with no errors where others fail.)

> Not only me, there are many
> people in recording industry believes so.

There are people in the recording industry who believe all sorts of
silly things, such as the idea that compressing the hell out of
recordings and letting them clip is good practice.

Part of the problem is that recording engineers often aren't.
Engineers, that is. So far as I can tell, you can succeed at being a
recording engineer without having anything beyond a very shallow
understanding of electrical (or any other form of) engineering.

> I hope daisy-laser people can reply this. As far as I am concern, I heard
> difference in CD-R and original. When I recorded at different speed, i heard
> difference. No pops or skips, just different. And I am sharing that with
> others.

See above. And did you hear difference in a DBT, or just an informal
test?

Everything I have ever read on the topic says that as you do more and
more tightly controlled experiments (in other words as you make more and
more sure that there cannot be any changing factors other than the one
you want to test), differences like these will disappear.

--
Tim

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

"John Atkinson" <Stereophile_Editor@Compuserve.com> wrote in message
news:3KhEc.126350$eu.114636@attbi_s02...
> "Timothy A. Seufert" <tas@mindspring.com> wrote in message
> news:<cbq7b701kqb@news3.newsguy.com>...

snip..snip..

> > >
> > > The resulting jitter affects the sound quality, as it blurs the
> > > sound representation and increases the high-frequency noise.
> >
> > So let me get this straight: you are arguing that errors in pit
> > lengths resulting in jitter in the signal read from the disc has
> > audible effects, even when there are no changes in data values?
>
> That is correct. While I wouldn't generalize the audible effect of
> jitter as "blurs the sound representation and increases the
> high-frequency noise," I had understood that it was generally
> accepted that time-base errors in the data read from the disc can
> result in measurable changes in the recovered analog signal.
>

Hmm, deafening silence. Perhaps it is too funny or they realised there is a
possibility for them to discover.

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

"Timothy A. Seufert" <tas@mindspring.com> wrote in message
news:<i6XEc.8236$MB3.1645@attbi_s04>...
> In article <3KhEc.126350$eu.114636@attbi_s02>,
> Stereophile_Editor@Compuserve.com (John Atkinson) wrote:
> > "Timothy A. Seufert" <tas@mindspring.com> wrote in message
> > news:<cbq7b701kqb@news3.newsguy.com>...
> > > So let me get this straight: you are arguing that errors in pit
> > > lengths resulting in jitter in the signal read from the disc has
> > > audible effects, even when there are no changes in data values?
> >
> > That is correct. While I wouldn't generalize the audible effect of
> > jitter as "blurs the sound representation and increases the
> > high-frequency noise," I had understood that it was generally
> > accepted that time-base errors in the data read from the disc can
> > result in measurable changes in the recovered analog signal.
>
> If and only if pit length / position errors cause a sufficiently high
> bit error rate in the raw datastream that there are errors in the
> recovered sample values after the C1 and C2 error correction algorithms
> do their work.
>
> In other words, as long as the bitstream delivered to the DAC is the
> same, the recovered analog signal is the same, within the limits of the
> DAC.

I wish that were the case. Stereophile has published quite a lot of work
showing, basically, that jitter propagates through a D/A system. It can be
low-pass filtered but not eliminated unless heroic measures are employed.

> Jitter in the clock used to write a disc cannot propagate to
> playback _as_jitter_, for the simple reason that playback uses an
> entirely independent clock source.

Again I wish that were the case. Yes, the data recovery clock controls the
retrieval of the bitstream from the disc and also controls the word-clock
timing of the DAC. But what may be perfect on paper may well not be in
practice. Time-base error can vary significantly on CDs -- check out some
discs with the Plextools software -- and some players do not eliminate it
as much as one might wish.

John Atkinson
Editor, Stereophile

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

John Atkinson <Stereophile_Editor@compuserve.com> wrote:
> "Timothy A. Seufert" <tas@mindspring.com> wrote in message
> news:<i6XEc.8236$MB3.1645@attbi_s04>...
> > In article <3KhEc.126350$eu.114636@attbi_s02>,
> > Stereophile_Editor@Compuserve.com (John Atkinson) wrote:
> > > "Timothy A. Seufert" <tas@mindspring.com> wrote in message
> > > news:<cbq7b701kqb@news3.newsguy.com>...
> > > > So let me get this straight: you are arguing that errors in pit
> > > > lengths resulting in jitter in the signal read from the disc has
> > > > audible effects, even when there are no changes in data values?
> > >
> > > That is correct. While I wouldn't generalize the audible effect of
> > > jitter as "blurs the sound representation and increases the
> > > high-frequency noise," I had understood that it was generally
> > > accepted that time-base errors in the data read from the disc can
> > > result in measurable changes in the recovered analog signal.
> >
> > If and only if pit length / position errors cause a sufficiently high
> > bit error rate in the raw datastream that there are errors in the
> > recovered sample values after the C1 and C2 error correction algorithms
> > do their work.
> >
> > In other words, as long as the bitstream delivered to the DAC is the
> > same, the recovered analog signal is the same, within the limits of the
> > DAC.
>
> I wish that were the case. Stereophile has published quite a lot of work
> showing, basically, that jitter propagates through a D/A system. It can be
> low-pass filtered but not eliminated unless heroic measures are employed.
>
> > Jitter in the clock used to write a disc cannot propagate to
> > playback _as_jitter_, for the simple reason that playback uses an
> > entirely independent clock source.
>
> Again I wish that were the case. Yes, the data recovery clock controls the
> retrieval of the bitstream from the disc and also controls the word-clock
> timing of the DAC. But what may be perfect on paper may well not be in
> practice. Time-base error can vary significantly on CDs -- check out some
> discs with the Plextools software -- and some players do not eliminate it
> as much as one might wish.

I note that Timothy was careful to mention *audible effects* up there, in
the post you originally replied to. Has Stereophile published results of
testing for *that*?

--

-S.
Why don't you just admit that you hate music and leave people alone. --
spiffy <thatsright@excite.co>

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

In article <cc299h01riu@news3.newsguy.com>,
Stereophile_Editor@Compuserve.com (John Atkinson) wrote:

> "Timothy A. Seufert" <tas@mindspring.com> wrote in message
> news:<i6XEc.8236$MB3.1645@attbi_s04>...
> > In article <3KhEc.126350$eu.114636@attbi_s02>,
> > Stereophile_Editor@Compuserve.com (John Atkinson) wrote:
> > > "Timothy A. Seufert" <tas@mindspring.com> wrote in message
> > > news:<cbq7b701kqb@news3.newsguy.com>...
> > > > So let me get this straight: you are arguing that errors in pit
> > > > lengths resulting in jitter in the signal read from the disc has
> > > > audible effects, even when there are no changes in data values?
> > >
> > > That is correct. While I wouldn't generalize the audible effect of
> > > jitter as "blurs the sound representation and increases the
> > > high-frequency noise," I had understood that it was generally
> > > accepted that time-base errors in the data read from the disc can
> > > result in measurable changes in the recovered analog signal.
> >
> > If and only if pit length / position errors cause a sufficiently high
> > bit error rate in the raw datastream that there are errors in the
> > recovered sample values after the C1 and C2 error correction algorithms
> > do their work.
> >
> > In other words, as long as the bitstream delivered to the DAC is the
> > same, the recovered analog signal is the same, within the limits of the
> > DAC.
>
> I wish that were the case. Stereophile has published quite a lot of work
> showing, basically, that jitter propagates through a D/A system. It can be
> low-pass filtered but not eliminated unless heroic measures are employed.

I'm afraid that I'm not inclined to give Stereophile articles much
credence when it comes to technical matters, having read many a howler
whenever said articles are brought to my attention. It's an
enterntainment magazine, not an engineering journal.

> > Jitter in the clock used to write a disc cannot propagate to
> > playback _as_jitter_, for the simple reason that playback uses an
> > entirely independent clock source.
>
> Again I wish that were the case. Yes, the data recovery clock controls the
> retrieval of the bitstream from the disc and also controls the word-clock
> timing of the DAC. But what may be perfect on paper may well not be in
> practice.

The practice is that there is an oscillator feeding the DAC clock input.
In order for your claim to be true, somehow random variations away from
ideal placement of pit/land transitions on the disc must affect that
oscillator's jitter. This strikes me as more than a little unlikely.

The only remotely plausible explanation for such an effect that I've
ever seen put forth is power supply noise, but there are problems with
that idea too. The biggest being, why should there be any more power
supply noise than normal? The number of CMOS switching events in the
digital section of the player should not be any higher on average. This
probably holds true even when there are extra bit errors to correct,
since correction is a decoding step which must be done regardless of
whether there are errors.

--
Tim

 

[Toni]

Archived from groups: rec.audio.high-end (More info?)

Hi all,

En John Atkinson va escriure en 2 Jul 2004 00:12:33 GMT:

>I wish that were the case. Stereophile has published quite a lot of work
>showing, basically, that jitter propagates through a D/A system. It can be
>low-pass filtered but not eliminated unless heroic measures are employed.

AFAIK, for jitter, you only need to read the CD into your laptop
computer and then play it through the optical out to your
amplifier. The stability of your PC clock with any medium quality
digital I/O card will be much greater than the direct read from
the rotating CD.

Toni

 

[Guest]

Archived from groups: rec.audio.high-end (More info?)

Stereophile_Editor@Compuserve.com (John Atkinson) wrote:

>"Timothy A. Seufert" <tas@mindspring.com> wrote in message
>news:<i6XEc.8236$MB3.1645@attbi_s04>...
>> In article <3KhEc.126350$eu.114636@attbi_s02>,
>> Stereophile_Editor@Compuserve.com (John Atkinson) wrote:
>> > "Timothy A. Seufert" <tas@mindspring.com> wrote in message
>> > news:<cbq7b701kqb@news3.newsguy.com>...
>> > > So let me get this straight: you are arguing that errors in pit
>> > > lengths resulting in jitter in the signal read from the disc has
>> > > audible effects, even when there are no changes in data values?
>> >
>> > That is correct. While I wouldn't generalize the audible effect of
>> > jitter as "blurs the sound representation and increases the
>> > high-frequency noise," I had understood that it was generally
>> > accepted that time-base errors in the data read from the disc can
>> > result in measurable changes in the recovered analog signal.
>>
>> If and only if pit length / position errors cause a sufficiently high
>> bit error rate in the raw datastream that there are errors in the
>> recovered sample values after the C1 and C2 error correction algorithms
>> do their work.
>>
>> In other words, as long as the bitstream delivered to the DAC is the
>> same, the recovered analog signal is the same, within the limits of the
>> DAC.
>
>I wish that were the case. Stereophile has published quite a lot of work
>showing, basically, that jitter propagates through a D/A system. It can be
>low-pass filtered but not eliminated unless heroic measures are employed.
>
>> Jitter in the clock used to write a disc cannot propagate to
>> playback _as_jitter_, for the simple reason that playback uses an
>> entirely independent clock source.
>
>Again I wish that were the case. Yes, the data recovery clock controls the
>retrieval of the bitstream from the disc and also controls the word-clock
>timing of the DAC. But what may be perfect on paper may well not be in
>practice. Time-base error can vary significantly on CDs -- check out some
>discs with the Plextools software -- and some players do not eliminate it
>as much as one might wish.
>
>John Atkinson
>Editor, Stereophile

What you say may well be true; I'll ask you if you have any bias-controlled
listening evidence that any of this will matter to a listener using his home
reference system? At anytime with any commercially available recordings?