Ron Capik wrote:

Isn't imaging, sound stage, (etc.) something contrived by the recordist,
mix engineer, and mastering engineer. Don't they all have an impact
on the spatial image?

They do.

But I know what concert hall X sounds like, at least from the seat I like.
When I put in this recording made in concert hall X, I want it to sound
like that. Does it?

If you weren't the engineer how could you possibly
map that vision to one's own listening space? Heck, with multi-tracking
the entire space is contrived. Who's to say what's ~more~ natural.

That's where the problems start coming in. I can say that I have a good
solid image that extends beyond the speakers and has a sense of depth to
it... but maybe that's not at all what they wanted when they created that
recording.

An A/B test may identify a difference but can it provide any insight into
which is closer to the producer's/engineer's vision (or should I say
auralization... ) ? Has anyone calibrated their listening room with respect
to the mastering studio? Just what was that target average listening room
anyway... ?

I don't know, but I know what the recordings I made are supposed to sound
like, so I can use them to judge equipment. I know what recordings made
in certain halls should sound like too. But if things don't sound like
that, is it the fault of the recording or equipment? How can anyone tell?

[We seem to have way more questions than answers.]

That's what makes audio fun.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Mike Rivers wrote:
In article writes:


I
keep reading these high end magazine reviews of products which the reviewer
claims to have great imaging even the tonality is poor.


I've never tried to listen for the effect of jitter since I don't have
a way to control it, but I recall some of Bob Katz' writings of half a
dozen or so years back. He was introducing what, by today's standards,
would be considered massive amounts of FM on a data clock and
listening to what happened when he turned it on and off. One effect
that he observed was that things that were clearly located in the
stereo field were no longer as clearly located. This same sort of
thing can be a result of crosstalk, phase shift in the signal chain,
maybe even listening position. But when he heard a change that he
described in this way by doing nothing but adding jitter to the clock,
it's not unreasonable to suggest that this is an effect of jitter.

Why it manifests itself aurally that way is for someone else to try to
explain.

But is there a measurement for this?

Mike Rivers wrote:

I've never tried to listen for the effect of jitter since
I don't have
a way to control it, but I recall some of Bob Katz'
writings of half a
dozen or so years back. He was introducing what, by
today's standards,
would be considered massive amounts of FM on a data clock
and
listening to what happened when he turned it on and off.
One effect
that he observed was that things that were clearly located
in the
stereo field were no longer as clearly located. This same
sort of
thing can be a result of crosstalk, phase shift in the
signal chain,
maybe even listening position. But when he heard a change
that he
described in this way by doing nothing but adding jitter
to the clock,
it's not unreasonable to suggest that this is an effect of
jitter.

The key words I see a

"by today's standards, would be considered massive amounts
of FM on a data clock and listening to what happened when
he turned it on and off"

This grants that today we'd only rarely if at all,
experience these levels of jitter.

IOW, Katz's experiences of years and years ago are almost
entirely irrelevant to our situations, today.

Joe Sensor wrote:
Mike Rivers wrote:
In article
writes:


I
keep reading these high end magazine reviews of products
which the
reviewer claims to have great imaging even the tonality
is poor.


I've never tried to listen for the effect of jitter since
I don't
have a way to control it, but I recall some of Bob Katz'
writings of
half a dozen or so years back. He was introducing what,
by today's
standards, would be considered massive amounts of FM on a
data clock
and listening to what happened when he turned it on and
off. One
effect that he observed was that things that were clearly
located in
the stereo field were no longer as clearly located. This
same sort of
thing can be a result of crosstalk, phase shift in the
signal chain,
maybe even listening position. But when he heard a change
that he
described in this way by doing nothing but adding jitter
to the
clock, it's not unreasonable to suggest that this is an
effect of
jitter.

Why it manifests itself aurally that way is for someone
else to try
to explain.

But is there a measurement for this?

Of course. Joe, for a guy who presents himself as an
authoritative critic of measurements, you sure as blazes
don't know anything about the topic.

IOW Joe, your critiques of measurements are actually
critiques of *your ignorance* about measurements.

In article writes:

Why it manifests itself aurally that way is for someone else to try to
explain.

But is there a measurement for this?

You could probably set up an experiment where the subject is required
to aim a pointer (maybe a laser) at an apparent sound source. Mount it
on a tripod calibrated for azimuth and elevation. You could even read it
digitally if you wanted to use your comptuer.

You could collect data on the scatter of his shots with and without jitter
and see if the angle of uncertainty is greater with jitter than without, and
by how much. Do this with a couple of hundred subjects and get back to
us with your results. g



--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
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Mike Rivers wrote:
In article

writes:

Why it manifests itself aurally that way is for someone
else to try
to explain.

But is there a measurement for this?

You could probably set up an experiment where the subject
is required
to aim a pointer (maybe a laser) at an apparent sound
source. Mount it
on a tripod calibrated for azimuth and elevation. You
could even read
it digitally if you wanted to use your comptuer.

This kind of experiment has been done, probably most
recently to study HRTFs.

You could collect data on the scatter of his shots with
and without
jitter and see if the angle of uncertainty is greater with
jitter
than without, and by how much. Do this with a couple of
hundred
subjects and get back to us with your results. g

The usual way to study the audibility of jitter is to
present people with jittered and unjittered audio samples,
level-matched and time-synched, and see whether they can
reliably discern *any difference at all*.

The answer is that if any of the sidebands created by jitter
are much below the -80 dB level, people generally can't
reliably discern any difference at all.

The overarching irony of this discussion is that as a rule,
digital recording systems have far lower jitter than analog
recording systems. In analog systems we call jitter stuff
like scrape flutter and general flutter and wow.

When is the last time you saw an analog tape or vinyl-based
system as good as 0.01% or less flutter and wow of *any*
kind, unweighted? Doesn't happen that good with analog.
0.01% corresponds to -80 dB jitter, which while generally
beyond SOTA for analog, is ****-poor performance for a good
digital system.

For the record, the thing that really bugs me about analog
are the problems with speed accuracy as well as audible
flutter and wow. Sue me for loving piano concertos! ;-)

Your typical pro-audio digital audio system runs with the
equivalent of something like 0.0001% or better total
unweighted flutter and wow. Any standard weighting scheme
just makes that spec look even better.

Joe Sensor wrote:
Mike Rivers wrote:
In article writes:
I
keep reading these high end magazine reviews of products which the reviewer
claims to have great imaging even the tonality is poor.


I've never tried to listen for the effect of jitter since I don't have
a way to control it, but I recall some of Bob Katz' writings of half a
dozen or so years back. He was introducing what, by today's standards,
would be considered massive amounts of FM on a data clock and
listening to what happened when he turned it on and off. One effect
that he observed was that things that were clearly located in the
stereo field were no longer as clearly located. This same sort of
thing can be a result of crosstalk, phase shift in the signal chain,
maybe even listening position. But when he heard a change that he
described in this way by doing nothing but adding jitter to the clock,
it's not unreasonable to suggest that this is an effect of jitter.

Why it manifests itself aurally that way is for someone else to try to
explain.

But is there a measurement for this?

Yes, there is. You can either measure gross jitter in picoseconds, or
you can use a modulation domain analyzer to measure the spectrum of the
jitter.

A good introduction to the measurement can be found in John D. Paul's
_Characterizing Digital Audio Transformers with Induced Jitter Histograms_,
AES preprint 5448.

Nobody has done a good study on perceived effects vs. jitter levels at
various frequencies, though.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

In article writes:

IOW, Katz's experiences of years and years ago are almost
entirely irrelevant to our situations, today.

Perhaps so, on the practical side of things (and I almost always argue
on the side of practicality) but he still says he can hear the effect
of jitter but is leaving it to manufacturers that know more than he
does to reduce its effect.

Still, he can show that it's possible for an untrained user to hear
the effect of jitter if there's enough of it. Some people can't tell
when frequency response cuts off at 10 kHz, or when mid-band THD
exceeds 5% either. But that doesn't mean that these can be neglected.


--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

Sure, but remember that Edison did plenty of public demonstrations with
his cylinder machines, where many folks claimed to be unable to distinguish
the live and recorded sound.


Those folks were probably shareholders. ;-)

Same things go on today.

In article writes:

The usual way to study the audibility of jitter is to
present people with jittered and unjittered audio samples,
level-matched and time-synched, and see whether they can
reliably discern *any difference at all*.

While it goes against your true double blind test methodology,
sometimes giving the test subject something specific to listen for (in
this case, the location of a particular sound) can give more
meaningful results than "any difference at all." Some people might not
think that not being able to pinpoint a sound is a difference.

The answer is that if any of the sidebands created by jitter
are much below the -80 dB level, people generally can't
reliably discern any difference at all.

Back to "distortion" again, I see.

The overarching irony of this discussion is that as a rule,
digital recording systems have far lower jitter than analog
recording systems. In analog systems we call jitter stuff
like scrape flutter and general flutter and wow.

Yes, but those have definite sonic artifacts. The "imaging" thing
isn't so well defined. I've never heard a digital system that has so
much clock instability as to sound like flutter. Nor have I heard
flutter in an analog recorder influence the location of a reproduced
sound (but I've never tried).

When is the last time you saw an analog tape or vinyl-based
system as good as 0.01% or less flutter and wow of *any*
kind, unweighted?

Different issue. Same with scrape flutter, which introduces
sidebands in the audible range.

For the record, the thing that really bugs me about analog
are the problems with speed accuracy as well as audible
flutter and wow. Sue me for loving piano concertos! ;-)

This is one of the greatest advantages of digital recording. I'm not
knocking it. But we're not talking about flutter when we talk about
the effect of clock jitter. If it's bad enough to hear as flutter, you
don't even think about the other potential problems.

Think about this - the clock controls the timing of the data,
including when the left and right channels of a stereo stream are
played. Suppose that timing gets noisy so that you get random changes
in phase between the two channels? You're likely to perceive this
as a fuzzy image rathen than as audible noise, frequency response
irregularities, or frequencies that weren't there in the original
recording.

--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

In article writes:

But is there a measurement for this?

Yes, there is. You can either measure gross jitter in picoseconds, or
you can use a modulation domain analyzer to measure the spectrum of the
jitter.

Arny's point is that jitter has on effect other than when it gets bad
enough to cause flutter. Measuring the amount of jitter is one thing.
Assessing its audible effects is another. You can measure the AC line
voltage going into a power amplifier with a voltmeter, but you need to
perform a different kind of test to tell that when it drops below 90
volts, it clips when putting out 30 watts instead of clipping at 150
watts.

Nobody has done a good study on perceived effects vs. jitter levels at
various frequencies, though.

I think that a more interesting study would be about the effects of
random jitter. Jitter at a fixed frequency is probably caused by
something that you can actually do something about. Not sure about
random jitter, though.


--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

In article znr1119975982k@trad, Mike Rivers wrote:
In article writes:

The answer is that if any of the sidebands created by jitter
are much below the -80 dB level, people generally can't
reliably discern any difference at all.

Back to "distortion" again, I see.

This is mostly correct, BUT audibility depends a lot on how far the
sideband is from the main lobe.

You can take the attitude that there is a point below which everything is
inaudible no matter how far out it is (which is what Arny does with
distortion), but if you do that you have to be damn sure that you picked
the a point low enough. Since I keep hearing weird things I cannot explain,
I sometimes wonder if the points are picked low enough. Looking at the
spectrum sometimes helps us explain things.

The overarching irony of this discussion is that as a rule,
digital recording systems have far lower jitter than analog
recording systems. In analog systems we call jitter stuff
like scrape flutter and general flutter and wow.

Yes, but those have definite sonic artifacts. The "imaging" thing
isn't so well defined. I've never heard a digital system that has so
much clock instability as to sound like flutter. Nor have I heard
flutter in an analog recorder influence the location of a reproduced
sound (but I've never tried).

The thing is that the jitter spectrum is usually very different than
the modulation domain spectrum of scrape flutter. You can use an old
Minicom test set into a spectrum analyzer to see the spectrum of the
phase noise of a tape machine and most of what you see is usually one
big rotational peak followed by a couple smaller ones. In the case
of a 440 most of what you see is at the frequency that the scrape flutter
idlers rotate at, or the frequency that the supply idler rotates, or
the capstan rotation frequency. One of the neat things about the 440
design is that all of these were carefully picked to be different
frequencies that weren't harmonically related. On the ATR-100 there's
really only one rotational peak but it's a lot smaller.

Anyway, if you're curious about how flutter influences imaging, check
out some of Jamie Howarth's demos on the Plangent Technologies website,
which I think is www.plangent.com. It's a magic box that removes
flutter from old analogue recordings by using residual bias as a pilot
reference tone. It's kind of weird hearing what happens when the flutter
is removed... things become more solid and defined and there is less of
a sense of instruments blending together.

When is the last time you saw an analog tape or vinyl-based
system as good as 0.01% or less flutter and wow of *any*
kind, unweighted?

Different issue. Same with scrape flutter, which introduces
sidebands in the audible range.

The last time I used an ATR-100. Did I mention that I really like the
ATR-100? Anyway, I think that jitter and flutter are two sides of the
same coin, but the end results are a little different because the spectra
are different. And I think eliminating BOTH of them will benefit the world.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

In article znr1119976280k@trad, Mike Rivers wrote:
In article writes:

Nobody has done a good study on perceived effects vs. jitter levels at
various frequencies, though.

I think that a more interesting study would be about the effects of
random jitter. Jitter at a fixed frequency is probably caused by
something that you can actually do something about. Not sure about
random jitter, though.

Well, we _do_ know that it's less audible when it's more random, and
more audible when it's all at one frequency. We've known that since
the efforts to deal with tape flutter in the sixties. That is why
folks designing PLLs for high-end DACs spend a lot of time looking
at plots and trying to get 60 Hz components and residual clock components
out of their clock error spectrum.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Mike Rivers wrote:
In article

writes:

The usual way to study the audibility of jitter is to
present people with jittered and unjittered audio
samples,
level-matched and time-synched, and see whether they can
reliably discern *any difference at all*.

While it goes against your true double blind test
methodology,
sometimes giving the test subject something specific to
listen for (in
this case, the location of a particular sound) can give
more
meaningful results than "any difference at all."

It doesn't go against any methodology of mine to give the
test subject something to listen for.

Thing is, jitter doesn't change the location where sound
comes from. If the jitter is *really* extreme (and in this
case it will be so extreme that you will probably hear some
other artifact first) you get a blurring of the image. But
its not like the image becomes wider, it just becomes more
vague. Vagueness is hard to pinpoint.

My preferred means for giving people something specific to
listen for is to set up a training test with such a big dose
of the effect being investigated that it is obvious and
unmistakable. I follow that up with smaller and smaller
amounts of the effect until it either becomes inaudible, or
the presentation is of a real-world quantity of the effect.

Some people might not
think that not being able to pinpoint a sound is a
difference.

The answer is that if any of the sidebands created by
jitter
are much below the -80 dB level, people generally can't
reliably discern any difference at all.

Back to "distortion" again, I see.

Well, jitter is FM distortion.

The overarching irony of this discussion is that as a
rule,
digital recording systems have far lower jitter than
analog
recording systems. In analog systems we call jitter stuff
like scrape flutter and general flutter and wow.

Yes, but those have definite sonic artifacts.

That's because they are so large.

The "imaging" thing isn't so well defined.

Exactly. It's hard to pinpoint vagueness.

I've never heard a digital system that has so
much clock instability as to sound like flutter.

Been there done that, but completely on purpose.

Nor have I heard
flutter in an analog recorder influence the location of a
reproduced
sound (but I've never tried).

See my previous comments about the effect of FM distortion
on imaging. You hear other artifacts first.

When is the last time you saw an analog tape or
vinyl-based
system as good as 0.01% or less flutter and wow of *any*
kind, unweighted?

Different issue.

Not really. Both digital and analog systems can introduce FM
distortion whose modulating frequency is say, 60 Hz (in the
US).

Admittedly, the most common FM modulating frequency for a LP
playback system is 0.555555 Hz and harmonics.

FM distortion is most audible at the lowest frequencies (as
in LP plyabck) , while the FM distortion in digital systems
is more likely to be at far higher frequencies which are
proportionately less audible.

Same with scrape flutter, which introduces
sidebands in the audible range.

Then there's the kind of jitter which is due to the signal
itself. That means that the distortion products are in the
audible range.

For the record, the thing that really bugs me about
analog
are the problems with speed accuracy as well as audible
flutter and wow. Sue me for loving piano concertos! ;-)

This is one of the greatest advantages of digital
recording. I'm not
knocking it. But we're not talking about flutter when we
talk about
the effect of clock jitter.

Sometimes yes, sometimes no.

If it's bad enough to hear as flutter, you
don't even think about the other potential problems.

Agreed.

Think about this - the clock controls the timing of the
data,
including when the left and right channels of a stereo
stream are
played. Suppose that timing gets noisy so that you get
random changes
in phase between the two channels?

Then you get vague imaging. Funny you should mention this -
in the past few days I posted about the effects of taking a
mono track and shifting it +45 degrees in one channel
and -45 degrees in the other. This adds spaciousness without
the nasty total cancellation in mono that you get when you
add spaciousness by inverting the polarity of one channel.

You're likely to perceive this
as a fuzzy image rathen than as audible noise, frequency
response
irregularities, or frequencies that weren't there in the
original
recording.

The ear tends to judge imaging over longer periods of time.
If you fuzz the image every random once in a while, the
listener might not notice it at all.

Scott Dorsey wrote:
In article znr1119975982k@trad, Mike Rivers

wrote:
In article

writes:

The answer is that if any of the sidebands created by
jitter
are much below the -80 dB level, people generally can't
reliably discern any difference at all.

Back to "distortion" again, I see.

This is mostly correct, BUT audibility depends a lot on
how far the
sideband is from the main lobe.

Agreed. When the FM sidebands are within the critical band
of the carrier, the ear perceives the modulation as
roughness. If they are outside the critical band, the ear
tends to perceive them as separate (usually aharmonic)
tones.

You can take the attitude that there is a point below
which
everything is inaudible no matter how far out it is (which
is what
Arny does with distortion), but if you do that you have to
be damn
sure that you picked the a point low enough.

Agreed.

Since I keep hearing
weird things I cannot explain, I sometimes wonder if the
points are
picked low enough. Looking at the spectrum sometimes
helps us
explain things.

Agreed.

The overarching irony of this discussion is that as a
rule,
digital recording systems have far lower jitter than
analog
recording systems. In analog systems we call jitter
stuff
like scrape flutter and general flutter and wow.

Yes, but those have definite sonic artifacts.

As does the most common or one of the most common forms of
jitter in poor systems, which is 60 Hz based in the US and
50 Hz based in most of the rest of the world.

The "imaging" thing
isn't so well defined. I've never heard a digital system
that has so
much clock instability as to sound like flutter. Nor have
I heard
flutter in an analog recorder influence the location of a
reproduced
sound (but I've never tried).

The thing is that the jitter spectrum is usually very
different than
the modulation domain spectrum of scrape flutter.

Agreed.

You can use an old
Minicom test set into a spectrum analyzer to see the
spectrum of the
phase noise of a tape machine and most of what you see is
usually one
big rotational peak followed by a couple smaller ones.

Vinyl tends to follow the same pattern. However there are
often two rotation frequencies, one of the whole disc, and
one related to the rotation of the drive motor.

In the case
of a 440 most of what you see is at the frequency that the
scrape
flutter idlers rotate at, or the frequency that the supply
idler
rotates, or
the capstan rotation frequency. One of the neat things
about the 440
design is that all of these were carefully picked to be
different
frequencies that weren't harmonically related. On the
ATR-100 there's
really only one rotational peak but it's a lot smaller.

I regret that I did not have good facilities to look at the
jitter artifacts in vinyl tape in the days when I was highly
comitted to it.

Anyway, if you're curious about how flutter influences
imaging, check
out some of Jamie Howarth's demos on the Plangent
Technologies
website, which I think is www.plangent.com. It's a magic
box that
removes
flutter from old analogue recordings by using residual
bias as a pilot
reference tone. It's kind of weird hearing what happens
when the
flutter is removed... things become more solid and defined
and there
is less of a sense of instruments blending together.

Here's the web site:

http://www.plangentprocesses.com/

Some nice audio samples there.

When is the last time you saw an analog tape or
vinyl-based
system as good as 0.01% or less flutter and wow of
*any*
kind, unweighted?

Different issue. Same with scrape flutter, which
introduces
sidebands in the audible range.

The last time I used an ATR-100. Did I mention that I
really like the
ATR-100? Anyway, I think that jitter and flutter are two
sides of the
same coin, but the end results are a little different
because the
spectra are different.

Let's say that they can and often are different, but there's
nothing that makes them always be different.

And I think eliminating BOTH of them will
benefit the world. --scott

Agreed. Digital was the practical solution to wow and
flutter. Plangent Processes technology is a highly complex
but effective after-the-fact solution.

In article writes:

Anyway, if you're curious about how flutter influences imaging, check
out some of Jamie Howarth's demos on the Plangent Technologies website,
which I think is www.plangent.com. It's a magic box that removes
flutter from old analogue recordings by using residual bias as a pilot
reference tone. It's kind of weird hearing what happens when the flutter
is removed... things become more solid and defined and there is less of
a sense of instruments blending together.

Yes, I remember hearing his AES demos, and last year he was pointing
this improved imaging out, but I couldn't really tell on the show
floor.

Anyway, I think that jitter and flutter are two sides of the
same coin, but the end results are a little different because the spectra
are different. And I think eliminating BOTH of them will benefit the world.

I had a chat with one of the engineers at AES about why their Big Ben
clock generator got so many rave reviews about making anything that it
clocked sound better. The amplitude of the jitter in their spec sheet
isn't really that much smaller than other good devices. He said that
it had to do with the spectrum (or probably it's really the
probability distribution) of the jitter. But he really didn't sound
very convincing.

--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

In article writes:

Thing is, jitter doesn't change the location where sound
comes from.

No (so I'm told - I'm NOT speaking from listening experience here) it
doesn't change the position. Turning the jitter on isn't going to make
the listener point the laser in a different position. The effect, as
it's been described, is that it makes a well defined location less
well defined. For example, without introducing jitter, the subject
pointing at the clarinet ten times might have all of his sightings
within, say a 15 degree angular range. Turn on the jitter and he'll
still be pointing in pretty much the same direction, but his aim might
be spread over a 30 degree range. Average out both sets of
measurements and you'll probably come out to pretty close to the same
angle, but for any single measurement, the chance of being further off
the actual position is greater with jitter.

But
its not like the image becomes wider, it just becomes more
vague. Vagueness is hard to pinpoint.

This is why it's difficult to test.

My preferred means for giving people something specific to
listen for is to set up a training test with such a big dose
of the effect being investigated that it is obvious and
unmistakable. I follow that up with smaller and smaller
amounts of the effect until it either becomes inaudible, or
the presentation is of a real-world quantity of the effect.

That would work, too, as long as you don't introduce so much jitter
that the listener hears warbling and thinks that's what he's supposed
to listen for.

Well, jitter is FM distortion.

More like FM random noise. But then I guess noise is distortion.

I've never heard a digital system that has so
much clock instability as to sound like flutter.

Been there done that, but completely on purpose.

Well, OK, me, too, but it took turning the dial on the oscillator that
I was using as a word clock. Extremes don't count when you're trying
to determine the presence of things that are both subtle and vague.


--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo

Arny Krueger wrote:

I regret that I did not have good facilities to look at the
jitter artifacts in vinyl tape in the days when I was highly
comitted to it.

That's okay, the guys at 3M did, and they wrote a bunch of papers in the
AES about it. Send e-mail to Bob Groschen here because I am sure he has
some citations.

It's actually not a very big deal with vinyl, at least not with a good
lathe, because you have a huge amount of mass on the platter to even
it out. You still have issues with the main bearing and with the
drive mechanism. On a Scully, which has multiple pulleys and belts,
I'd bet that a flutter spectrum will show a peak for each one, but I
also bet the platter mass makes them all pretty minimal.

There are some playback systems, most notably direct drive turntables,
that have massive amounts of cogging. This results in one huge peak
in the phase noise spectrum. This is a known problem and easily avoided
by not using crappy DJ turntables.

Agreed. Digital was the practical solution to wow and
flutter. Plangent Processes technology is a highly complex
but effective after-the-fact solution.

Now you have to convince the digital guys to use decent clocking, though.
The word is getting around, but it's still not out enough.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On 28 Jun 2005 21:00:50 -0400, (Mike Rivers)
wrote:

Well, jitter is FM distortion.

More like FM random noise. But then I guess noise is distortion.

Or, as you're *way* too subtly implying, not.

Thanks, as always,

Chris Hornbeck
"Untestable does not mean meaningless."
-Joe Sensor

Mike Rivers wrote:

In article writes:

Thing is, jitter doesn't change the location where sound
comes from.

No (so I'm told - I'm NOT speaking from listening experience here) it
doesn't change the position. Turning the jitter on isn't going to make
the listener point the laser in a different position. The effect, as
it's been described, is that it makes a well defined location less
well defined. For example, without introducing jitter, the subject
pointing at the clarinet ten times might have all of his sightings
within, say a 15 degree angular range. Turn on the jitter and he'll
still be pointing in pretty much the same direction, but his aim might
be spread over a 30 degree range. Average out both sets of
measurements and you'll probably come out to pretty close to the same
angle, but for any single measurement, the chance of being further off
the actual position is greater with jitter.

But
its not like the image becomes wider, it just becomes more
vague. Vagueness is hard to pinpoint.

This is why it's difficult to test.
...snip..

Another aspect to consider is the relative spatial impact on harmonics.
By that I mean will all the harmonics of said clarinet point to the same
point(s) in space. Will (can, do,) the highs rotate about a the locus
of the fundamental or randomly jump about or some such. I would
expect that spatial variance would be frequency dependent.
Are left and right track jitter highly correlated?

Later...

Ron Capik
--

"Ron Capik" wrote in message

Mike Rivers wrote:

In article
writes:

Thing is, jitter doesn't change the location where sound
comes from.

No (so I'm told - I'm NOT speaking from listening
experience
here) it doesn't change the position. Turning the jitter
on
isn't going to make the listener point the laser in a
different position. The effect, as it's been described,
is
that it makes a well defined location less
well defined. For example, without introducing jitter,
the
subject pointing at the clarinet ten times might have all
of
his sightings within, say a 15 degree angular range. Turn
on
the jitter and he'll still be pointing in pretty much the
same direction, but his aim might be spread over a 30
degree
range. Average out both sets of
measurements and you'll probably come out to pretty close
to
the same angle, but for any single measurement, the
chance of
being further off the actual position is greater with
jitter.

But
its not like the image becomes wider, it just becomes
more
vague. Vagueness is hard to pinpoint.

This is why it's difficult to test.
...snip..

Another aspect to consider is the relative spatial impact
on
harmonics. By that I mean will all the harmonics of said
clarinet point to the same point(s) in space.

All the harmonics of a source don't always point to the same
point(s) in space, even without jitter. Reflections at
least partially localize to the reflective surface, not the
source. Reflected sounds may or may not have timbre shifts.

Arny Krueger wrote:

"Ron Capik" wrote in message


...snip..
Another aspect to consider is the relative spatial impact
on
harmonics. By that I mean will all the harmonics of said
clarinet point to the same point(s) in space.

All the harmonics of a source don't always point to the same
point(s) in space, even without jitter. Reflections at
least partially localize to the reflective surface, not the
source. Reflected sounds may or may not have timbre shifts.

Yes, the spatial character of the real world is dynamic and very
complex. However, note that I said ~relative~ spatial impact. Thus
I'm asking if disproportionate shifting of the spatial distribution,
what
ever that natural spatial distribution might be, may be taking place.
Maybe a bit like chromatic aberration on an undulating screen.

Also note that both tape and vinyl have the right and left tracks
mechanically linked.

Later...

Ron Capik
--

On Thu, 30 Jun 2005 15:40:12 GMT, Ron Capik
wrote:

Arny Krueger wrote:
All the harmonics of a source don't always point to the same
point(s) in space, even without jitter. Reflections at
least partially localize to the reflective surface, not the
source. Reflected sounds may or may not have timbre shifts.

Yes, the spatial character of the real world is dynamic and very
complex. However, note that I said ~relative~ spatial impact. Thus
I'm asking if disproportionate shifting of the spatial distribution,
what
ever that natural spatial distribution might be, may be taking place.
Maybe a bit like chromatic aberration on an undulating screen.

Also note that both tape and vinyl have the right and left tracks
mechanically linked.

've been trying to think about y'all's question without much
progress. Maybe the problem could be simplified to just
considering the first-arrival sounds (first), and then
working on the general case.

Very interesting; good fortune,

Chris Hornbeck
"Betty, is that Jimmy's ring you're wearing?"
'um huh."
"Gee, it must be great riding with him.
Is he picking you up after school today?"
"unh uh"
"By the way, where'd you meet him?"

Chris Hornbeck wrote:

On Thu, 30 Jun 2005 15:40:12 GMT, Ron Capik
wrote:

...snip..
Yes, the spatial character of the real world is dynamic and very
complex. However, note that I said ~relative~ spatial impact. Thus
I'm asking if disproportionate shifting of the spatial distribution,
what
ever that natural spatial distribution might be, may be taking place.
Maybe a bit like chromatic aberration on an undulating screen.

Also note that both tape and vinyl have the right and left tracks
mechanically linked.

've been trying to think about y'all's question without much
progress. Maybe the problem could be simplified to just
considering the first-arrival sounds (first), and then
working on the general case.

Very interesting; good fortune,

Chris Hornbeck

For what it's worth, my conjecture would work just fine
addressing direct (first arrival) effects. 'twas Arny that
added reflective surfaces.

In my conjecture said source has an image, as complex
or simple an image as you care to envision. Does jitter
have a frequency dependent or frequency neutral
impact on that image?

Later...

Ron
--

" ...y' get the picture? "
"Yes, we see... "