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Jitter and CD-R

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Anonymous
June 21, 2004 6:46:59 PM

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.

More about : jitter

June 22, 2004 2:20:46 AM

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
Anonymous
June 22, 2004 9:03:09 AM

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?
Related resources
Anonymous
June 22, 2004 6:53:00 PM

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
June 22, 2004 6:53:11 PM

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
Anonymous
June 23, 2004 3:05:40 AM

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
Anonymous
June 23, 2004 3:13:56 AM

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
Anonymous
June 24, 2004 3:11:32 AM

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
Anonymous
June 24, 2004 3:13:47 AM

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.
Anonymous
June 24, 2004 8:16:05 PM

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
Anonymous
June 25, 2004 2:46:34 AM

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.
Anonymous
June 25, 2004 2:47:57 AM

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.
Anonymous
June 29, 2004 2:50:15 AM

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
Anonymous
June 29, 2004 8:44:13 PM

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.
Anonymous
June 29, 2004 9:33:51 PM

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
Anonymous
June 30, 2004 2:42:44 AM

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.
>
Anonymous
June 30, 2004 6:53:11 AM

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
Anonymous
July 1, 2004 8:38:38 PM

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
Anonymous
July 2, 2004 2:45:08 AM

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
Anonymous
July 2, 2004 4:11:24 AM

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.
Anonymous
July 2, 2004 4:12:33 AM

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
Anonymous
July 2, 2004 6:41:41 AM

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>
Anonymous
July 2, 2004 4:08:15 PM

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
July 2, 2004 8:09:01 PM

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
Anonymous
July 2, 2004 8:09:50 PM

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?
Anonymous
July 2, 2004 8:09:58 PM

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

Steven Sullivan <ssully@panix.com> wrote in message news:<FX3Fc.10987$7t3.2143@attbi_s51>...
> John Atkinson <Stereophile_Editor@compuserve.com> wrote:
> > "Timothy A. Seufert" <tas@mindspring.com> wrote in message
> > news:<i6XEc.8236$MB3.1645@attbi_s04>...
> > > 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.

I didn't address audibility, except that that if there are measurable
differences in the analog signal, there may well be audible
differences.
In this response I was specifically addressing his statement that:
> > > 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.

Which is incorrect. There are measurable differences in the
reconstructed
analog signal from the same bitstream, that result from different
anounts and types of word-clock jitter. If they are measurable, they
may
well be audible. For example, I once was a subject in a single-blind
test
comparing the same data on CD and CD-R, where the CD-R sounded
different.

> Has Stereophile published results of testing for [audibility of jitter]?

No formal tests of audibility, but a lot of anecdotal evidence. A 1993
article on the subject will be accessible in the free on-line archives
at www.stereophile.com on Monday July 5.

John Atkinson
Editor, Stereophile
July 3, 2004 11:34:44 AM

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

John Atkinson wrote:
> "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.
>

Seems like an ideal tool for checking the green-pen claim. If there was
an effect, it had to affect the block error rate or time-base errors,
no? Has Stereophile tried doing that?

> John Atkinson
> Editor, Stereophile
Anonymous
July 3, 2004 6:55:52 PM

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

Toni <post_to_usenet@hotmail.com> wrote in message
news:<xMfFc.13105$%_6.3916@attbi_s01>...
> 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.

As I said, "heroic" measures. Not many audiophiles will tolerate a
delay of 60+ minutes before they can hear their music.

> 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.

Maybe, maybe not. I don't think you can draw such general conclusions.

John Atkinson
Editor, Stereophile
Anonymous
July 4, 2004 11:39:58 AM

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

In message <cc3j7f02icj@news2.newsguy.com>
Timothy A. Seufert (tas@mindspring.com) wrote:
> 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>...
> > > 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.

Arguing by credential is never very productive, Mr. Seufert. I'd
rather
we stick to the issue at hand. I will return to the subject of
"howlers"
at the end of this posting. In the meantime, if you doubt the articles
in Stereophile, I suggest you read Barry Blesser's compendium on
digital
audio in the October 1978 issue of the Journal of the Audio
Engineering
Society, where the problems of word-clock jitter were first described
in an audio context (to the best of my knowledge).

A Stereophile article showing how different analog signals can be
reconstructed from identical bitstreams can be found at
http://www.stereophile.com/reference/1290jitter. This, too, is based
on
an AES paper, this time by Stephen Harris, and a third article can be
found at http://www.stereophile.com/reference/590jitter. A fourth
article,
showing measured differences, goes up in the stereophile.com archives
on
Monday. Before you dismiss all this work as "howlers," I politely
suggest you should read it.

> It's an entertainment magazine, not an engineering journal.

That may well be true, at least partially, but it doesn't mean that
you are entitled to dismiss everything that is published in
Stereophile.
In the case of the effects of word-clock jitter on the reconstructed
analog signal, I am not aware of anything published in Stereophile
that
is at odds with what has been published in academic journals or
textbooks.
(Note that I am not talking about audibility here, but the observable
effect on the analog signal.)

> > > 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.

You may think it unlikely, Mr. Seufert, but that doesn't mean it
doesn't
exist. The problem is that there is no clock in the disc data. (The
problem of an AES/EBU datastream, where there is a clock embedded in
the data is somewehat different, but manifests itself in a similar
manner in the DAC.) The CD player's crystal oscillator you mention
must
therefore control both the DAC and the disc rotation. The signal
retrieved
from the rotating disc is actually analog in nature. Much processing
is
therefore required to reconstruct a digital bitstream to be fed to the
DAC, including some kind of memory buffer.

As I wrote, timing uncertainties in the raw data retrieval do appear
to
propagate through this system, resulting in measurable effects in the
recovered analog signal. Things like buffers and PLLs low-pass filter
the timing uncertainty but do not eliminate it, unfortunately.

That a CD-R carrying identical data to a CD can sound different is
described in in article at http://www.stereophile.com/asweseeit/523.

> 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.

Around 12 years ago, this subject was examined by Ed Meitner and Bob
Gendron in an AES paper. To their surprise, they found -- and I
duplicated their work -- that riding on the DC power rail supplying
the
ICs in a DAC was the audio signal described by the data that was being
processed. If you think about it, this is astonishing. Check it out.

Back to the subject of supposed technical "howlers" in Stereophile
magazine. As editor, I try hard to keep the incidence of errors to an
acceptably low level. When the subject has come up before on r.a.h-e
or
other newsgroups, I have therefore asked the posters to be specific.
If,
indeed, there is a factual error in the magazine, I need to be aware
of
it. There are 4 specific examples in the groups.google.com record:

Example 1: A John Busenitz mentioned, as you have just done, Mr.
Seufert,
the purported high incidence of techical errors in Stereophile. It
turned
out that Mr. Busenitz was only able to cite one example of such an
error,
but it didn't actually appear in Stereophile. It was in a book written
by
Stereophile's one-time technical editor, Robert Harley.

Example 2: I wrote in Stereophile a number of years ago that the AC
signal is not carried in the conductor but in the dielectric around
that conductor. A number of posters seized on this as being a
"howler."
Unfortunately for the critics, my description was technically correct.

Example 3: Tom Nousaine correctly criticized a blind amplifier test
published in a 1989 issue of Stereophile on the grounds that there
were a different number of Same and Different presentations.

Example 4: Arny Krueger has repeatedly criticized the listening tests
performed in Stereophile's reviews on the grounds that the majority of
them are performed sighted. He is correct; they are.

All the other examples mentioned on the newsgroups either appeared in
magazines other than Stereophile; were matters of opinion not fact; or
concerned things, such as Shun Mook tweaks, that the poster thought
unworthy of magazine coverage.

So, Mr. Seufert, if you have a specific example of a technical
"howler"
that was published in Stereophile, please let me know what it was, so
I can ensure we don't make the same error in future. Thank you.

John Atkinson
Editor, Stereophile
Anonymous
July 4, 2004 12:16:49 PM

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

On 3 Jul 2004 14:55:52 GMT, Stereophile_Editor@Compuserve.com (John
Atkinson) wrote:

>Toni <post_to_usenet@hotmail.com> wrote in message
> news:<xMfFc.13105$%_6.3916@attbi_s01>...
>> 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.
>
>As I said, "heroic" measures. Not many audiophiles will tolerate a
>delay of 60+ minutes before they can hear their music.

Absolute rubbish if you know *anything* about the technology. A delay
of 4 seconds is more than adequate for *total* buffering and
reclocking. Ask Meridian, who do use this technique in their 800
series. One might have hoped that the Editor of Stereophile would be
aware of this. One might also have hoped that he'd be aware of
asynchronous resampling, as used by the superb (and state of the art,
and reviewed by Stereophile) Benchmark DAC-1..............

--

Stewart Pinkerton | Music is Art - Audio is Engineering
Anonymous
July 4, 2004 6:53:37 PM

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

chung <chunglau@covad.net> wrote:
> John Atkinson wrote:
> > "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.
> >

> Seems like an ideal tool for checking the green-pen claim. If there was
> an effect, it had to affect the block error rate or time-base errors,
> no? Has Stereophile tried doing that?

For how many years did the CD Stoplight make the Stereophile 'Recommended
Comnponents' list, anyway?

Plextools came with all (nonprofessional) Plextor CDRW drives I've bought
in the last few years, btw.

--

-S.
"We started to see evidence of the professional groupie in the early 80's.
Alarmingly, these girls bore a striking resemblance to Motley Crue." --
David Lee Roth
Anonymous
July 4, 2004 6:56:02 PM

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

On 3 Jul 2004 14:55:52 GMT, Stereophile_Editor@Compuserve.com (John
Atkinson) wrote:

>As I said, "heroic" measures. Not many audiophiles will tolerate a
>delay of 60+ minutes before they can hear their music.

Hm, the RAM of a PC has lots of jitter due to its refresh cycles.
Thus the samples are stored in the playback buffer of a sound card.
The sound card has a local clock which controls its A/D and D/A chips
and any chips for digital audio i/o.

IMHO it is sufficient to buffer the audio for 10 ms in the buffer of
the sound card. A 60+ minutes buffer is not needed.

Do you happen to know the size of the buffers (note plural) in a
(audio) CD player?

Norbert
Anonymous
July 4, 2004 11:02:58 PM

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

"John Atkinson" <Stereophile_Editor@compuserve.com> wrote in message
news:ivOFc.20695$%_6.4910@attbi_s01...
In the meantime, if you doubt the articles
> in Stereophile, I suggest you read Barry Blesser's compendium on
> digital
> audio in the October 1978 issue of the Journal of the Audio
> Engineering
> Society, where the problems of word-clock jitter were first described
> in an audio context (to the best of my knowledge).
>
> an AES paper, this time by Stephen Harris, and a third article can be
> found at http://www.stereophile.com/reference/590jitter. A fourth
> article,
> showing measured differences, goes up in the stereophile.com archives
> on
> Monday. Before you dismiss all this work as "howlers," I politely
> suggest you should read it.
>
> > It's an entertainment magazine, not an engineering journal.
>
> That may well be true, at least partially, but it doesn't mean that
> you are entitled to dismiss everything that is published in
> Stereophile.

It's more than a bit annoying to me (at least) that words to the effect of
information having appeared in academic journals are the equivalent of god's
word. It would help to know if *that* journal uses peer review for
acceptance for publication OR if any and all submitted papers are published.
Even if the former be true, however, there are "errata" and retractions, and
although not very common, such do take place. I'm not in favor of tossing
out published papers or dismissing scientific facts, but am simply saying
that just because some data AND their subsequent *interpretation* and
conclusions have appeared therein, one cannot simply accept such as given
immutable truths.
Anonymous
July 5, 2004 8:57:14 AM

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

On Sun, 04 Jul 2004 07:39:58 GMT, Stereophile_Editor@compuserve.com
(John Atkinson) wrote:

>A Stereophile article showing how different analog signals can be
>reconstructed from identical bitstreams can be found at
>http://www.stereophile.com/reference/1290jitter. This, too, is based
>on
>an AES paper, this time by Stephen Harris, and a third article can be
>found at http://www.stereophile.com/reference/590jitter. A fourth article,
>showing measured differences, goes up in the stereophile.com archives on
>Monday. Before you dismiss all this work as "howlers," I politely
>suggest you should read it.

Hardly new knowledge. Jitter has been acknowledged as a problem in
digital audio since the '60s - telecomms being several decades ahead
of so-called 'high end' audio, as usual.

>> > > 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.

It is...........

>> > 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.
>
>You may think it unlikely, Mr. Seufert, but that doesn't mean it doesn't
>exist. The problem is that there is no clock in the disc data.

Exactly! In a standalone player, the only clock is the free-running
DAC clock, which also controls the data-reading servo. Hence, *if*
that clock has vanishingly low phase noise, and *if* the power
supplies are absolutely clean, there can be no jitter in the output
signal, other than that of the A/D converter used to make the original
digital master.

> (The
>problem of an AES/EBU datastream, where there is a clock embedded in
>the data is somewehat different, but manifests itself in a similar
>manner in the DAC.)

No, it manifests itself in an *entirely* different manner.

> The CD player's crystal oscillator you mention must
>therefore control both the DAC and the disc rotation. The signal retrieved
>from the rotating disc is actually analog in nature.

So what? It still produces a stream of ones and zeros, with an error
rate of less than one in ten *million* from any modern transport mech
and associated electronics. Hardly an audible problem........

> Much processing is
>therefore required to reconstruct a digital bitstream to be fed to the
>DAC, including some kind of memory buffer.

Yes, a FIFO buffer timed by the DAC master clock.

>As I wrote, timing uncertainties in the raw data retrieval do appear to
>propagate through this system, resulting in measurable effects in the
>recovered analog signal. Things like buffers and PLLs low-pass filter
>the timing uncertainty but do not eliminate it, unfortunately.

Unfortunately for your theory, there are *no* PLLs in a well-designed
CD player, and the buffer is a FIFO unit, clocked by the free-running
DAC master clock, so there is *no* attenuation involved, simply a
total *lack* of dependence on the jitter of the raw signal as
retrieved from the disc.

>That a CD-R carrying identical data to a CD can sound different is
>described in in article at http://www.stereophile.com/asweseeit/523.
>
>> 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.
>
>Around 12 years ago, this subject was examined by Ed Meitner and Bob
>Gendron in an AES paper. To their surprise, they found -- and I
>duplicated their work -- that riding on the DC power rail supplying the
>ICs in a DAC was the audio signal described by the data that was being
>processed. If you think about it, this is astonishing. Check it out.

It's not really astonishing, but it *is* a sign of poor system design.
See any current Meridian player for a fine example of how it should be
done - or just hook up any old transport to a Benchmark DAC-1.

It's unfortunate that your august publication still makes the fatal
error of assuming that a DAC which actually *is* sensitive to
different transports is somehow 'superior', when the plain *fact* is
that it's basically broken.
--

Stewart Pinkerton | Music is Art - Audio is Engineering
July 5, 2004 9:08:28 AM

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

Steven Sullivan wrote:

> chung <chunglau@covad.net> wrote:
>> John Atkinson wrote:
>> > "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.
>> >
>
>> Seems like an ideal tool for checking the green-pen claim. If there was
>> an effect, it had to affect the block error rate or time-base errors,
>> no? Has Stereophile tried doing that?
>
> For how many years did the CD Stoplight make the Stereophile 'Recommended
> Comnponents' list, anyway?

I guess this supports the view that Stereophile is an entertainment
magazine. This also really destroys the credibility of the "Recommended
Components" list, IMO.

>
> Plextools came with all (nonprofessional) Plextor CDRW drives I've bought
> in the last few years, btw.
>
Anonymous
July 5, 2004 9:08:41 AM

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

Stewart Pinkerton <patent3@dircon.co.uk> wrote in message
news:<R1PFc.22187$Oq2.18326@attbi_s52>...
> On 3 Jul 2004 14:55:52 GMT, Stereophile_Editor@Compuserve.com (John
> Atkinson) wrote:
> >Toni <post_to_usenet@hotmail.com> wrote in message
> > news:<xMfFc.13105$%_6.3916@attbi_s01>...
> >> 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.
> >
> >As I said, "heroic" measures. Not many audiophiles will tolerate a
> >delay of 60+ minutes before they can hear their music.
>
> Absolute rubbish if you know *anything* about the technology. A delay
> of 4 seconds is more than adequate for *total* buffering and
> reclocking.

Two points Stewart. First, is that a 4s buffer falls, I think, under
the category of "heroic" measures. However, the buffer output clock
still needs to be tied to the long-term average of the incoming
dataclock and that is the pathway for low-frequency jitter, unless
the circuit topology is optimal. I have just reviewed a DAC designed
by r.a.p. regular Dan Lavry, who has some intersting ideas on this.

Second, is that I was addressing "Toni"'s suggestion that CD playback
jitter would be eliminated if the disc's content were first stored on
hard disk. Yes, it would be possible to start reading the disc, then
start outputting the data after a delay of about 4s, which would perhaps
be sufficent, but again, this falls under the "heroic measure" heading,
IMO.

> Ask Meridian, who do use this technique in their 800 series.

Yes, Meridian does do this. It should be noted that the players are
_very_ expensive. Normal-priced CD players do not have anything like
4s' worth of FIFO, though with memory as cheap as it is I do not know
why.

John Atkinson
Editor, Stereophile
Anonymous
July 5, 2004 6:30:57 PM

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

On Mon, 05 Jul 2004 05:08:41 GMT, Stereophile_Editor@compuserve.com
(John Atkinson) wrote:

>Stewart Pinkerton <patent3@dircon.co.uk> wrote in message
>news:<R1PFc.22187$Oq2.18326@attbi_s52>...
>> On 3 Jul 2004 14:55:52 GMT, Stereophile_Editor@Compuserve.com (John
>> Atkinson) wrote:
>> >Toni <post_to_usenet@hotmail.com> wrote in message
>> > news:<xMfFc.13105$%_6.3916@attbi_s01>...
>> >> 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.
>> >
>> >As I said, "heroic" measures. Not many audiophiles will tolerate a
>> >delay of 60+ minutes before they can hear their music.
>>
>> Absolute rubbish if you know *anything* about the technology. A delay
>> of 4 seconds is more than adequate for *total* buffering and
>> reclocking.
>
>Two points Stewart. First, is that a 4s buffer falls, I think, under
>the category of "heroic" measures.

Agreed - but not what you said above.

>However, the buffer output clock
>still needs to be tied to the long-term average of the incoming
>dataclock and that is the pathway for low-frequency jitter, unless
>the circuit topology is optimal.

No, it doesn't - that is the whole *point* of genuine reclocking. The
allowable clock frequency tolerance for CDs is such that a 4 second
buffer is adequate to avoid overrun or underrun after 80 minutes. Of
course, Benchmark have shown in the DAC-1 that an asynchronous
re-sampler can provide an equally good solution to incoming jitter,
with no such delay.

>I have just reviewed a DAC designed
>by r.a.p. regular Dan Lavry, who has some intersting ideas on this.
>
>Second, is that I was addressing "Toni"'s suggestion that CD playback
>jitter would be eliminated if the disc's content were first stored on
>hard disk. Yes, it would be possible to start reading the disc, then
>start outputting the data after a delay of about 4s, which would perhaps
>be sufficent, but again, this falls under the "heroic measure" heading,
>IMO.

In terms of applying a 'brute force' solution, yes, but not much of a
drawback to any typical audiophile. Compare and contrast with the time
it takes to put on an LP............

>> Ask Meridian, who do use this technique in their 800 series.
>
>Yes, Meridian does do this. It should be noted that the players are
>_very_ expensive. Normal-priced CD players do not have anything like
>4s' worth of FIFO, though with memory as cheap as it is I do not know
>why.

OTOH, the Benchmark DAC-1, which I believe has been reviewed by
Stereophile, is equally immune to jitter in the incoming datastream,
and costs less than $1,000 - i.e. less than many of your recommended
cables!
--

Stewart Pinkerton | Music is Art - Audio is Engineering
July 5, 2004 6:31:22 PM

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

Hi Atkinson and Norbert,

(Oops, and hello to everybody as I just "jumped in" without
presenting me to the group)

please let answer to both in the same post:

En Norbert Hahn va escriure en 4 Jul 2004 14:56:02 GMT:

>On 3 Jul 2004 14:55:52 GMT, Stereophile_Editor@Compuserve.com (John
>Atkinson) wrote:
>
>>As I said, "heroic" measures. Not many audiophiles will tolerate a
>>delay of 60+ minutes before they can hear their music.

A delay of 60+' is not realistic. Most PCs will read a CD in < 8'
+ once you have loaded it it can stay in your hard disk for as
long as you / Windows want.

As for the heroic measure I'm not so sure. A laptop is in the
price range of medium to good speakers and surely less expansive
than what some call "true high-end" transports.

Another advantage, if you want to give the time to it is, that
you can extract the audio with one of those programs that will
re-read the audio blocks as many times as required to guarantee
that they match and there are no bit read errors. This is
impossible to do in real-time in a normal CD reader. This I would
accept in the "heroic measure".

>Hm, the RAM of a PC has lots of jitter due to its refresh cycles.
>Thus the samples are stored in the playback buffer of a sound card.
>The sound card has a local clock which controls its A/D and D/A chips
>and any chips for digital audio i/o.
>
>IMHO it is sufficient to buffer the audio for 10 ms in the buffer of
>the sound card. A 60+ minutes buffer is not needed.

This is completely true. Thinking of it, you don't even need to
pre-read the CD, as the PC is able to read the CD faster than
real time and buffer in RAM. An external USB SPDIF card would
guarantee a second _externally_clocked_ buffer not influenced by
the PC's internal electrical noise. The maniacs could even
replace the card's crystal by a high-quality custom-made one (not
very expensive, most electronics shops will order them for you).

Toni
Anonymous
July 5, 2004 6:47:03 PM

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

"Norman Schwartz" <nmsz1@att.net> wrote in message
news:<CvYFc.23081$%_6.1517@attbi_s01>...
> "John Atkinson" <Stereophile_Editor@compuserve.com> wrote in message
> news:ivOFc.20695$%_6.4910@attbi_s01...
> In the meantime, if you doubt the articles
> > in Stereophile, I suggest you read Barry Blesser's compendium on
> > digital audio in the October 1978 issue of the Journal of the
> > Audio Engineering Society, where the problems of word-clock jitter
> > were first described in an audio context (to the best of my
> > knowledge)...
>
> It's more than a bit annoying to me (at least) that words to the
> effect of information having appeared in academic journals are the
> equivalent of god's word. It would help to know if *that* journal uses
> peer review for acceptance for publication...

Papers that are published in the Journal of the AUdio Engineering
Society are indeed peer-reviewed.

John Atkinson
Editor, Stereophile
(Member AES)
Anonymous
July 7, 2004 11:08:24 AM

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

In article <_CdGc.27466$IQ4.7481@attbi_s02>,
Toni <post_to_usenet@hotmail.com> wrote:

>The maniacs could even
> replace the card's crystal by a high-quality custom-made one (not
> very expensive, most electronics shops will order them for you).

Curious as to what you mean by "high quality" in this context?

What, exactly, is "low quality" about the stock one?

Isaac
Anonymous
July 7, 2004 11:10:04 AM

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

Stewart Pinkerton <patent3@dircon.co.uk> wrote in message
news:<Kc5Gc.24114$MB3.7322@attbi_s04>...
> On Sun, 04 Jul 2004 07:39:58 GMT, Stereophile_Editor@compuserve.com
> (John Atkinson) wrote:
>> if you doubt the articles in Stereophile, I suggest you read Barry
>> Blesser's compendium on digital audio in the October 1978 issue of
>> the Journal of the Audio Engineering Society, where the problems of
>> word-clock jitter were first described in an audio context (to the
>> best of my knowledge). A Stereophile article showing how different
>> analog signals can be reconstructed from identical bitstreams can
>> be found at http://www.stereophile.com/reference/1290jitter. This,
>> too, is based on an AES paper, this time by Stephen Harris, and a
>> third article can be found at
>> http://www.stereophile.com/reference/590jitter. A fourth article,
>> showing measured differences, goes up in the stereophile.com
>> archives on Monday.
>
> Hardly new knowledge. Jitter has been acknowledged as a problem in
> digital audio since the '60s - telecomms being several decades
> ahead of so-called 'high end' audio, as usual.

With respect Stewart, I think you are being a tad disingenuous here.
Yes, the problems of jitter were known in telecommunications work.
But it was only with the advent of practical digital audio in the
1970s, with the pioneering work of the BBC in the UK, Sony, NHK and
Denon in Japan, and 3M and the late Dr. Thomas Stockham at Soundstream
in the US, that digital theory became applicable to audio. Far from
the Blesser paper that I mentioned being "decades" behind, it was
published in 1978, just a handful of years after the first digital
audio devices were prototyped. Bob Stuart's work on jitter reduction
in Meridian players followed the Blesser paper by a decade, but that
was still just 5 years after the commercial launch of the CD medium.

>> You may think it unlikely, Mr. Seufert, but that doesn't mean it
>> doesn't exist. The problem is that there is no clock in the disc
>> data.
>
> Exactly! In a standalone player, the only clock is the free-running
> DAC clock, which also controls the data-reading servo. Hence, *if*
> that clock has vanishingly low phase noise, and *if* the power
> supplies are absolutely clean, there can be no jitter in the output
> signal, other than that of the A/D converter used to make the
> original digital master.

I really don't think we disagree, Stewart. I would say that my position
is that your word "if" conceals a multitude of design sins on the part
of product designers, sins that, according to the measurements
published in Stereophile and other review magazines, allow time-base
errors to propagate through to the recovered analog signal. I agree
with you that such design sins are poor engineering; I would merely
point out to you and Mr. Mr. Seufert that because something in theory
can be made to be perfect, that doesn't mean all real-world solutions
are also perfect.

<snip>

>> Around 12 years ago, this subject was examined by Ed Meitner and
>> Bob Gendron in an AES paper. To their surprise, they found -- and I
>> duplicated their work -- that riding on the DC power rail supplying
>> the ICs in a DAC was the audio signal described by the data that was
>> being processed. If you think about it, this is astonishing.
>
> It's not really astonishing, but it *is* a sign of poor system design.

I agree Stewart, But it is also not uncommon in cost-compromised
players with inadequate power supplies. Again, practical implementation
of theoretically perfect circuit topologies can leave a lot to be desired.

> See any current Meridian player for a fine example of how it should
> be done - or just hook up any old transport to a Benchmark DAC-1.

Yup. The Benchmark is an extraordinary product. Its designer, BTW,
claims that it will pass EEC RF emission standards with its cover
removed, which, if true, is a testament to the layout of its pcb.

> It's unfortunate that your august publication still makes the fatal
> error of assuming that a DAC which actually *is* sensitive to
> different transports is somehow 'superior', when the plain *fact*
> is that it's basically broken.

I am not sure that Stereophile has said this, at least not since the
early 1990s (if then). When you say "still makes" this error, Stewart,
are you aware of a recent instance?

John Atkinson
Editor, Stereophile
Anonymous
July 7, 2004 11:10:23 AM

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

Stewart Pinkerton <patent3@dircon.co.uk> wrote:
> On 3 Jul 2004 14:55:52 GMT, Stereophile_Editor@Compuserve.com (John
> Atkinson) wrote:

> >Toni <post_to_usenet@hotmail.com> wrote in message
> > news:<xMfFc.13105$%_6.3916@attbi_s01>...
> >> 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.
> >
> >As I said, "heroic" measures. Not many audiophiles will tolerate a
> >delay of 60+ minutes before they can hear their music.

> Absolute rubbish if you know *anything* about the technology. A delay
> of 4 seconds is more than adequate for *total* buffering and
> reclocking. Ask Meridian, who do use this technique in their 800
> series. One might have hoped that the Editor of Stereophile would be
> aware of this. One might also have hoped that he'd be aware of
> asynchronous resampling, as used by the superb (and state of the art,
> and reviewed by Stereophile) Benchmark DAC-1..............

I assumed he meant that it takes 60+ minutes to read a CD into a
laptop and play it through a 'real' stereo system. Not that it
makes much sense that way; it takes me a few minutes at most to burn
a CD to my hard drive.

--

-S.
"We started to see evidence of the professional groupie in the early 80's.
Alarmingly, these girls bore a striking resemblance to Motley Crue." --
David Lee Roth
July 7, 2004 7:19:13 PM

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

En Isaac Wingfield va escriure en Wed, 07 Jul 2004 07:08:24 GMT:

>In article <_CdGc.27466$IQ4.7481@attbi_s02>,
> Toni <post_to_usenet@hotmail.com> wrote:
>
>>The maniacs could even
>> replace the card's crystal by a high-quality custom-made one (not
>> very expensive, most electronics shops will order them for you).
>
>Curious as to what you mean by "high quality" in this context?
>
>What, exactly, is "low quality" about the stock one?

Hi Isaac

AFAIK, "low quality" cristals are those being more bulnerable to
microphonics and temperature changes. It depends mostly on
manufacturing and packaging conditions (that is cristal in
capsule packaging). Some people debate about different stability
of same frequency cristals on old big containers, normal
containers or micro-miniature packaging.

Small but constant frequency errors and long term variation with
temperature are probably not critical for this application, but
microphonics could cause more jitter than the one it is trying to
cure in the first place.

Toni
Anonymous
July 8, 2004 9:28:40 AM

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

On Wed, 07 Jul 2004 07:10:04 GMT, Stereophile_Editor@compuserve.com
(John Atkinson) wrote:

>Stewart Pinkerton <patent3@dircon.co.uk> wrote in message
>news:<Kc5Gc.24114$MB3.7322@attbi_s04>...
>> On Sun, 04 Jul 2004 07:39:58 GMT, Stereophile_Editor@compuserve.com
>> (John Atkinson) wrote:
>>> if you doubt the articles in Stereophile, I suggest you read Barry
>>> Blesser's compendium on digital audio in the October 1978 issue of
>>> the Journal of the Audio Engineering Society, where the problems of
>>> word-clock jitter were first described in an audio context (to the
>>> best of my knowledge). A Stereophile article showing how different
>>> analog signals can be reconstructed from identical bitstreams can
>>> be found at http://www.stereophile.com/reference/1290jitter. This,
>>> too, is based on an AES paper, this time by Stephen Harris, and a
>>> third article can be found at
>>> http://www.stereophile.com/reference/590jitter. A fourth article,
>>> showing measured differences, goes up in the stereophile.com
>>> archives on Monday.
>>
>> Hardly new knowledge. Jitter has been acknowledged as a problem in
>> digital audio since the '60s - telecomms being several decades
>> ahead of so-called 'high end' audio, as usual.
>
>With respect Stewart, I think you are being a tad disingenuous here.
>Yes, the problems of jitter were known in telecommunications work.
>But it was only with the advent of practical digital audio in the
>1970s, with the pioneering work of the BBC in the UK, Sony, NHK and
>Denon in Japan, and 3M and the late Dr. Thomas Stockham at Soundstream
>in the US, that digital theory became applicable to audio.

Hardly. Digital theory was *always* applicable to audio, and most of
telecomms *is* audio.................

> Far from
>the Blesser paper that I mentioned being "decades" behind, it was
>published in 1978, just a handful of years after the first digital
>audio devices were prototyped.

And well before CD was launched.

> Bob Stuart's work on jitter reduction
>in Meridian players followed the Blesser paper by a decade, but that
>was still just 5 years after the commercial launch of the CD medium.

Yes, and Bob Stuart has consistently been at least a decade ahead of
the so-called 'high end' brands in real engineering.

>>> You may think it unlikely, Mr. Seufert, but that doesn't mean it
>>> doesn't exist. The problem is that there is no clock in the disc
>>> data.
>>
>> Exactly! In a standalone player, the only clock is the free-running
>> DAC clock, which also controls the data-reading servo. Hence, *if*
>> that clock has vanishingly low phase noise, and *if* the power
>> supplies are absolutely clean, there can be no jitter in the output
>> signal, other than that of the A/D converter used to make the
>> original digital master.
>
>I really don't think we disagree, Stewart. I would say that my position
>is that your word "if" conceals a multitude of design sins on the part
>of product designers, sins that, according to the measurements
>published in Stereophile and other review magazines, allow time-base
>errors to propagate through to the recovered analog signal.

And this atrocious incompetence is signally most noticeable in
products which *you* place in Class A..............................

> I agree
>with you that such design sins are poor engineering; I would merely
>point out to you and Mr. Mr. Seufert that because something in theory
>can be made to be perfect, that doesn't mean all real-world solutions
>are also perfect.

Agreed - so why do you keep promoting grossly overpriced mediocrity
such as the Mark Levinson and Forsell CD devices? Not to mention your
earlier espousal of such ludicrously incompetent trash as the YBA
'blue laser' player?

>>> Around 12 years ago, this subject was examined by Ed Meitner and
>>> Bob Gendron in an AES paper. To their surprise, they found -- and I
>>> duplicated their work -- that riding on the DC power rail supplying
>>> the ICs in a DAC was the audio signal described by the data that was
>>> being processed. If you think about it, this is astonishing.
>>
>> It's not really astonishing, but it *is* a sign of poor system design.
>
>I agree Stewart, But it is also not uncommon in cost-compromised
>players with inadequate power supplies. Again, practical implementation
>of theoretically perfect circuit topologies can leave a lot to be desired.

However, both Meridian and Arcam seem able to provide essentially
immaculate performance without crippling price tags............

>> See any current Meridian player for a fine example of how it should
>> be done - or just hook up any old transport to a Benchmark DAC-1.
>
>Yup. The Benchmark is an extraordinary product. Its designer, BTW,
>claims that it will pass EEC RF emission standards with its cover
>removed, which, if true, is a testament to the layout of its pcb.

Indeed - so why is it not right at the top of your recommended list,
with about ten dollar signs?

>> It's unfortunate that your august publication still makes the fatal
>> error of assuming that a DAC which actually *is* sensitive to
>> different transports is somehow 'superior', when the plain *fact*
>> is that it's basically broken.
>
>I am not sure that Stereophile has said this, at least not since the
>early 1990s (if then). When you say "still makes" this error, Stewart,
>are you aware of a recent instance?

I confess that I have rather lost interest in S'pile since about 2001,
as it regrettably seemed to have fallen into the TAS morass, with
little of real interest to say to the inquiring mind................

If you have 'seen the light', and become more coherent (yuk, yuk),
then I'll be glad to reconsider.
--

Stewart Pinkerton | Music is Art - Audio is Engineering
Anonymous
July 8, 2004 8:54:43 PM

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

Stewart Pinkerton <patent3@dircon.co.uk> wrote in message
news:<cY4Hc.44459$Oq2.8565@attbi_s52>...
> On Wed, 07 Jul 2004 07:10:04 GMT, Stereophile_Editor@compuserve.com
> (John Atkinson) wrote:
> >Stewart Pinkerton <patent3@dircon.co.uk> wrote in message
> >news:<Kc5Gc.24114$MB3.7322@attbi_s04>...
> >> It's unfortunate that your august publication still makes the fatal
> >> error of assuming that a DAC which actually *is* sensitive to
> >> different transports is somehow 'superior', when the plain *fact*
> >> is that it's basically broken.
> >
> >I am not sure that Stereophile has said this, at least not since the
> >early 1990s (if then). When you say "still makes" this error, Stewart,
> >are you aware of a recent instance?
>
> I confess that I have rather lost interest in [Stereophile] since about
> 2001, as it regrettably seemed to have fallen into the TAS morass,
> with little of real interest to say to the inquiring mind...

In other words, you cannot qote an instance of this "still" being said
in Stereophile. Oh well...

John Atkinson
Editor, Stereophile
Anonymous
July 9, 2004 6:46:29 PM

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

In article <ivOFc.20695$%_6.4910@attbi_s01>,
Stereophile_Editor@compuserve.com (John Atkinson) wrote:

> In message <cc3j7f02icj@news2.newsguy.com>
> Timothy A. Seufert (tas@mindspring.com) wrote:
> > 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.
>
> Arguing by credential is never very productive, Mr. Seufert.

To be sure, but if you wish to cite Stereophile as a serious technical
authority, you'd better be prepared for howls of derision.

> In the meantime, if you doubt the articles
> in Stereophile, I suggest you read Barry Blesser's compendium on
> digital
> audio in the October 1978 issue of the Journal of the Audio
> Engineering
> Society, where the problems of word-clock jitter were first described
> in an audio context (to the best of my knowledge).

I don't have access to that article (it may be on the AES web site, but
if it is, I can't get at it because the AES web site is down at the
moment). However, I assure you that I am well aware of jitter issues
through first-hand experience in a different but related field.

> A Stereophile article showing how different analog signals can be
> reconstructed from identical bitstreams can be found at
> http://www.stereophile.com/reference/1290jitter. This, too, is based
> on
> an AES paper, this time by Stephen Harris, and a third article can be
> found at http://www.stereophile.com/reference/590jitter. A fourth
> article,
> showing measured differences, goes up in the stereophile.com archives
> on
> Monday. Before you dismiss all this work as "howlers," I politely
> suggest you should read it.

That word clock jitter can affect the output of a DAC is not
controversial, no matter how much you try to present it as such.

I note that you frequently attempt to build a strawman of the "bits is
bits" crowd as a bunch of ignoramuses who believe such jitter is
completely inconsequential. No, we just think it's not an issue in
systems designed by competent engineers, and that jitter cannot
mystically propagate across barriers it shouldn't be able to cross.

Speaking of such barriers, what we have in fact been discussing is the
notion that jitter in the positions of pits and lands on a CD can affect
the analog output of common CD playback system designs, even when there
are no uncorrectable bit errors induced by pit/land position errors.
Would you care to address that topic?

> > 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.
>
> You may think it unlikely, Mr. Seufert, but that doesn't mean it
> doesn't
> exist. The problem is that there is no clock in the disc data.

Actually, the _feature_ is that there is no clock in the disc data.

> (The
> problem of an AES/EBU datastream, where there is a clock embedded in
> the data is somewehat different, but manifests itself in a similar
> manner in the DAC.) The CD player's crystal oscillator you mention
> must
> therefore control both the DAC and the disc rotation.

This is not a problem.

> The signal
> retrieved
> from the rotating disc is actually analog in nature.

Not in any sense that most engineers would think of as "analog". There
are two states, and binary information is encoded by the spatial
location of transitions between the two states. Absolute signal levels
do not matter so long as the contrast is sufficient to reliably
discriminate between the two states and avoid false edge transitions.
These are the characteristics typical of a digital signaling system, not
analog.

> Much processing
> is
> therefore required to reconstruct a digital bitstream to be fed to the
> DAC, including some kind of memory buffer.

But of course it requires a memory buffer; couldn't perform the
essential decoding and error correction steps without a buffer. And
that buffer also happens to be why jitter is not an issue during
playback.

> As I wrote, timing uncertainties in the raw data retrieval do appear
> to
> propagate through this system, resulting in measurable effects in the
> recovered analog signal. Things like buffers and PLLs low-pass filter
> the timing uncertainty but do not eliminate it, unfortunately.

Here we begin to see how you lead yourself astray. A PLL buffer does in
some ways act like a low-pass filter for jitter, but the buffer in a CD
player does not involve a PLL. In any reasonably well designed player,
that buffer's output and the DAC input are both clocked by a single
reference clock, not a clock synthesis or recovery circuit such as a
PLL. This means the jitter of the DAC word clock is simply unrelated to
timing uncertainties in the section of the player which decodes raw data
from the disc.

> That a CD-R carrying identical data to a CD can sound different is
> described in in article at http://www.stereophile.com/asweseeit/523.

This article is singularly unimpressive, being little more than a
collection of anecdotes. The one bit that is interesting mentions a
blind test but gives absolutely no details about the test design, so
that the reader cannot but wonder whether the test truly was blind...

> > 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.
>
> Around 12 years ago, this subject was examined by Ed Meitner and Bob
> Gendron in an AES paper. To their surprise, they found -- and I
> duplicated their work -- that riding on the DC power rail supplying
> the
> ICs in a DAC was the audio signal described by the data that was being
> processed. If you think about it, this is astonishing. Check it out.

That would indeed be astonishing, but you are astonishingly failing to
consider a far simpler and more likely explanation, given what a DAC
_does_.

> Back to the subject of supposed technical "howlers" in Stereophile
> magazine. As editor, I try hard to keep the incidence of errors to an
> acceptably low level. When the subject has come up before on r.a.h-e
> or
> other newsgroups, I have therefore asked the posters to be specific.
> If,
> indeed, there is a factual error in the magazine, I need to be aware
> of
> it. There are 4 specific examples in the groups.google.com record:
>
> Example 1: A John Busenitz mentioned, as you have just done, Mr.
> Seufert,
> the purported high incidence of techical errors in Stereophile. It
> turned
> out that Mr. Busenitz was only able to cite one example of such an
> error,
> but it didn't actually appear in Stereophile. It was in a book written
> by
> Stereophile's one-time technical editor, Robert Harley.

Well then, let us examine Mr. Harley's writing _for your magazine_.

Here he makes more or less the same error you are making now:

"Jitter is most often introduced by mechanical imperfections in digital
audio-storage devices. A CD player's rotational servo, for example, can
introduce time-base errors (jitter) in the recovered signal if its speed
varies even by a tiny amount."

From: http://www.stereophile.com/reference/590jitter/index2.h...

--
Tim
Anonymous
July 9, 2004 6:48:00 PM

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

In article <cch49h01dvp@news1.newsguy.com>,
Toni <post_to_usenet@hotmail.com> wrote:

> En Isaac Wingfield va escriure en Wed, 07 Jul 2004 07:08:24 GMT:
>
> >In article <_CdGc.27466$IQ4.7481@attbi_s02>,
> > Toni <post_to_usenet@hotmail.com> wrote:
> >
> >>The maniacs could even
> >> replace the card's crystal by a high-quality custom-made one (not
> >> very expensive, most electronics shops will order them for you).
> >
> >Curious as to what you mean by "high quality" in this context?
> >
> >What, exactly, is "low quality" about the stock one?
>
> Hi Isaac
>
> AFAIK, "low quality" cristals are those being more bulnerable to
> microphonics and temperature changes. It depends mostly on
> manufacturing and packaging conditions (that is cristal in
> capsule packaging). Some people debate about different stability
> of same frequency cristals on old big containers, normal
> containers or micro-miniature packaging.
>
> Small but constant frequency errors and long term variation with
> temperature are probably not critical for this application, but
> microphonics could cause more jitter than the one it is trying to
> cure in the first place.

The things you describe affect essentially all crystals to just about
the same extent, assuming they are not actually broken.

In my experience, "high quality" mostly means, w.r.t. crystals,:

(1) the actual frequency of operation is closer to the specified
frequency. But note that even "non-precision" units are well within 50
parts per million, usually closer to ten ppm.

(2) the variation of frequency with temperature is less. But note that
even "ordinary" crystals are not likely to show enough drift to be
measured unless you have some pretty fancy lab equipment.

In almost every inside-a-computer or inside-consumer-electronics
application, ordering a "high quality" crystal without having a serious
understanding of exactly how the circuit was designed would be a waste
of money and might possible result in worse performance, not better. For
a "high quality" application, you need to know whether the crystal is in
a series or parallel configuration, and what the drive level and shunt
capacitance are, for starters.

Especially for "high quality" performance, the design of the oscillator
circuit that the crystal goes in is actually more important than the
crystal itself. Virtually every oscillator circuit used in consumer
audio applications will be of a type that simply cannot take advantage
of a crystal having higher precision or better temperature stability.
Most of the oscillators I've seen are actually pretty incompetently
designed and certainly could not take advantage of a superior crystal.
It's sometimes amazing that they work at all.

I know of exactly one situation where microphonics affected a crystal
oscillator in a way that was detrimental to the operation of the
equipment. The oscillator was the frequency control element for an FM
transmitter, and the microphonics were being caused by a snap-action
thermostat *inside* the crystal oven. That's a big "click" very close to
the crystal; nothing we could do from outside the unit had any noticable
effect on the oscillator. That particular crystal was physically much
larger, and operated at a significantly lower frequency than anything
I've seen in consumer gear. The large size and low frequency exacerbated
it's sensitivity to microphonics.

Isaac
Anonymous
July 9, 2004 8:32:39 PM

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

In article <n%eHc.46717$XM6.41060@attbi_s53>,
Stereophile_Editor@compuserve.com (John Atkinson) wrote:

> Stewart Pinkerton <patent3@dircon.co.uk> wrote in message
> news:<cY4Hc.44459$Oq2.8565@attbi_s52>...
> > On Wed, 07 Jul 2004 07:10:04 GMT, Stereophile_Editor@compuserve.com
> > (John Atkinson) wrote:
> > >Stewart Pinkerton <patent3@dircon.co.uk> wrote in message
> > >news:<Kc5Gc.24114$MB3.7322@attbi_s04>...
> > >> It's unfortunate that your august publication still makes the fatal
> > >> error of assuming that a DAC which actually *is* sensitive to
> > >> different transports is somehow 'superior', when the plain *fact*
> > >> is that it's basically broken.
> > >
> > >I am not sure that Stereophile has said this, at least not since the
> > >early 1990s (if then). When you say "still makes" this error, Stewart,
> > >are you aware of a recent instance?
> >
> > I confess that I have rather lost interest in [Stereophile] since about
> > 2001, as it regrettably seemed to have fallen into the TAS morass,
> > with little of real interest to say to the inquiring mind...
>
> In other words, you cannot qote an instance of this "still" being said
> in Stereophile. Oh well...

He missed the Arcam cd player on the July cover, too.

Stephen
!