On 2007-05-23, Serge Auckland wrote:

"Steve Swift" wrote in message
...

What plausible causes exist for the audio being different when the
individual bits being read off the CD are not? They may arrive with subtly
differing timings, but the sequence is identical. I'm sure the timing of
the bits varies every time a CD is played, due to varying rotational
speeds of the CD.

If you can do a double-blind test, and he can do this reliably, then you
have something. The only mechanism I can think of that could *possibly*
account for sonic differences is if the copy is so poorly burnt that the CD
player has a hard time reading the disc and there's a lot of interpolation
going on. It would then be useful to repeat the DBT using another CD player
of competely different type to see if the same results are obtained.
Otherwise, two bit-identical CDs will necessarily sound the same.

A common audiophile postulate for audibility of different discs of
nominally identical material is "jitter".

This surprises me a little, having looked at some AES papers on the
audibility thresholds for jitter. Although the research does says that
audible jitter at 10 kHz and above is remarkably low.

Also it seems to me that the jitter hypothesis relies on inadequate
engineering of clock extraction circuits to allow enough jitter to get
through to the audio output. Quite possible I suppose, but eminently
curable (and should not happen in the first place).

--
John Phillips

"John Phillips" wrote in message
...
On 2007-05-23, Serge Auckland wrote:

"Steve Swift" wrote in message
...

What plausible causes exist for the audio being different when the
individual bits being read off the CD are not? They may arrive with
subtly
differing timings, but the sequence is identical. I'm sure the timing of
the bits varies every time a CD is played, due to varying rotational
speeds of the CD.

If you can do a double-blind test, and he can do this reliably, then you
have something. The only mechanism I can think of that could *possibly*
account for sonic differences is if the copy is so poorly burnt that the
CD
player has a hard time reading the disc and there's a lot of
interpolation
going on. It would then be useful to repeat the DBT using another CD
player
of competely different type to see if the same results are obtained.
Otherwise, two bit-identical CDs will necessarily sound the same.

A common audiophile postulate for audibility of different discs of
nominally identical material is "jitter".

This surprises me a little, having looked at some AES papers on the
audibility thresholds for jitter. Although the research does says that
audible jitter at 10 kHz and above is remarkably low.

Also it seems to me that the jitter hypothesis relies on inadequate
engineering of clock extraction circuits to allow enough jitter to get
through to the audio output. Quite possible I suppose, but eminently
curable (and should not happen in the first place).

--
John Phillips

Quite so! There's no excuse these days for jitter. However, this doesn't
seem to have got through to some designers of "audiophile" DACs. One DAC I
saw reviewed (I can't remember which one but it was expensive!) made the
comment that it was so sensitive, it would reveal the differences between
digital cables. What this meant was that it had such an appallingly
engineered receiver that there was no reclocking of data, and pattern jitter
on the cable went uncorrected. So much for "so sensitive", crap actually.

S.

--
http://audiopages.googlepages.com

In article , Serge Auckland
wrote:


One DAC I saw reviewed (I can't remember which one but it was
expensive!) made the comment that it was so sensitive, it would reveal
the differences between digital cables. What this meant was that it had
such an appallingly engineered receiver that there was no reclocking of
data, and pattern jitter on the cable went uncorrected. So much for "so
sensitive", crap actually.

It *was* 'sensitive' - the problem was that it shouldn't have been! :-)

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

On 2007-05-24, Jim Lesurf wrote:
In article , Serge Auckland
wrote:

One DAC I saw reviewed (I can't remember which one but it was
expensive!) made the comment that it was so sensitive, it would reveal
the differences between digital cables. What this meant was that it had
such an appallingly engineered receiver that there was no reclocking of
data, and pattern jitter on the cable went uncorrected. So much for "so
sensitive", crap actually.

It *was* 'sensitive' - the problem was that it shouldn't have been! :-)

Steady on! That's the same heresy as "an amplifier should just amplify
and its output should not depend on the particular speakers it drives."
It's the uncultured engineer's philosophy and the antithesis of the
right-minded thinking of those who enjoy music. :-)

--
John Phillips

In article , John Phillips
wrote:

A common audiophile postulate for audibility of different discs of
nominally identical material is "jitter".

This surprises me a little, having looked at some AES papers on the
audibility thresholds for jitter. Although the research does says that
audible jitter at 10 kHz and above is remarkably low.

Also it seems to me that the jitter hypothesis relies on inadequate
engineering of clock extraction circuits to allow enough jitter to get
through to the audio output. Quite possible I suppose, but eminently
curable (and should not happen in the first place).

I may be wrong, but it is my impression that 'jitter' is falling out of
fashion as a 'reason' for the comments made about the 'sound' of players.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

On 2007-05-24, Jim Lesurf wrote:
In article , John Phillips
wrote:

A common audiophile postulate for audibility of different discs of
nominally identical material is "jitter".
...
I may be wrong, but it is my impression that 'jitter' is falling out of
fashion as a 'reason' for the comments made about the 'sound' of players.

Possibly, but not in all quarters. From two different online reviews
in the recent edition of Stereophile (just the first place I looked):

"It is hard to predict the subjective effect of such high
jitter, but a flat, rather uninvolving presentation would be my
suggestion. I do note that Wes Phillips found that the Oppo player
sounded somewhat soft and overripe in the midbass, which is one
consequence of high amounts of random jitter, in my experience."

(http://www.stereophile.com/cdplayers...po/index5.html)

and

"However, both systems indicated some slight spectral spreading of
the central peak in the graph, due to the presence of some random
low-frequency jitter. Paul Miller has conjectured that this produces
a somewhat larger depiction of objects within the soundstage than is
strictly accurate, coupled with a rather laid-back presentation."

(http://www.stereophile.com/cdplayers/507nag/index4.html)

--
John Phillips

"Steve Swift the Slow Wit "


I know this is probably holy war territory, but I'm hoping for some
interesting ideas.


** Spoken just like any died in the wool

TROLLING ****WIT !!



My brother-in-law claims ......


** Then go get the dumb **** to post here himself.

So we can ALL have some fun with the autistic cretin.



... to be able to hear the difference between the ..


What plausible causes exist...


** Bewa irrational, logical fallacy in action.

Facts must first be * established as correct * BEFORE one searches for
hypotheses.

****wit audiophool asses like YOU never learn.




........ Phil

Phil Allison wrote:


So we can ALL have some fun with the autistic cretin.

while I agree with plenty of what you post on here

Being autistic does not mean, someone is a cretin

"Dave xxxx"

Phil Allison wrote:


So we can ALL have some fun with the autistic cretin.

while I agree with plenty of what you post on here

Being autistic does not mean, someone is a cretin



** ROTFL !!

Dave the ****wit posts exactly like any congenital autistic.

Sees only the words - but not the meaning.





....... Phil

"Steve Swift" wrote in message


My brother-in-law claims to be able to hear the
difference

Testible with blind, level-matched, time-synched tests. If he obtains the
above opinion in a sighted evaluation, or one that is not properly
time-matched, then he is reporting a difference that is an artifact of his
crappy evaluation method.

between the original and the copy, but only
when the copy was written at greater than 4x speed.

Possible, if you have a CD player that is unduely sensitive to playing
CD-Rs.

What plausible causes exist for the audio being different
when the individual bits being read off the CD are not?

The data being read off the CD have two properties - the binary status of
the bits, and the timing of the bits. The CD player is supposed to address
all relevant issues related to both. So, if the CD player is defective, the
bits could be the same, the timing could be different, and an audible
difference might result.

They may arrive with subtly differing timings, but the
sequence is identical. I'm sure the timing of the bits
varies every time a CD is played, due to varying
rotational speeds of the CD.

The timing changes you suggest are routine and well-known.

The CD player has a lot of circuitry in it to make the timing right again.