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PStamler PStamler is offline
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It is alleged that even fairly benign speakers such as AR3s would force the
protective circuits to react audibly.


AR3s weren't all that benign. First off, they had unusually low
sensitivity, meaning they needed more voltage than yer average speaker
to produce a given SPL.

Second, trey were nominally 4 ohms, in an era when 8 ohm speakers were
the norm, and they could dip down to 3 ohms at some frequencies,
meaning they also needed a lot of current to produce a given SPL.

Finally, it was the beginning of the era when rock music was taken
seriously by audio fans, who had mostly listened to classical, jazz
and Persuasive Percussion. In his excellent book on solid-state power
amp design, Bob Cordell discusses how repeated low-frequency signals
(read: kickdrum hits) can interact with the back-EMF from an
underdamped woofer (the AR speakers had a Qtc of 1.1, meaning they
were mildly underdamped) to make the speaker draw a good deal more
current than its nominal impedance rating would imply. The AR3s, when
hit by kickdrum-type signals, demanded current levels corresponding to
an effective load impedance of 1-1.5 ohms.

Most of the craze for super-powered amplifiers in the 1970s (think
Phase Linear, Ampzilla, etc.) was fueled by the desire to drive AR-
type speakers to high volumes on rock music. It took a while for folks
to realize that current delivery mattered more than raw power, and
that an amp which voltage-clipped at, say, 100W (but with ample
current capability) could do as well as a "700W" amplifier. I have
such an amp (from Parasound) in the other room, and it will drive just
about anything happily. Doesn't burn up, either.

Peace,
Paul
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William Sommerwerck William Sommerwerck is offline
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"Mxsmanic" wrote in message
...
anahata writes:


I obviously don't know the technical details of your story, but my
first reaction would be to question whether what you get when you
download a YouTube video (for comparison with the "original") is
exactly what you get when you play it in real time.


I was going by the audio files he gave me, and he claimed that there
was a huge, horrible difference between them. I did the nulling test
and found essentially no difference at all, and I trust the numbers
more than I trust his ear or his ego.


I think YouTube probably adopted the same position that I did. You
can't fix something that isn't broken.


As for Ethan's "Audio Myths" video, I saw that a couple of weeks
ago and there's a lot of good stuff there, though I'm not sure sure
everyone would agree with his views about the (un)importance of
dither.


If I understand dither correctly, then his assertion that it isn't
important seems reasonable.


It costs nothing to properly dither the signal. Therefore, there's no reason
not to do it.

The reason that an undithered signal /doesn't/ sound awful, is that musical
tones are rarely at (or close-enough to) sub-multiples of the sampling
frequency, and/or don't last long enough, for correlated quantization error
to be audible.

To hear what this error sounds like, listen to a test CD with an undithered
sweep tone. (I think the Denons are undithered, but I don't remember.)


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"Arny Krueger" wrote in message
...
"William Sommerwerck" wrote in message
...


There are two good reasons for dither.


First, it prevents obvious distortion when a musical note is a
"sub-multiple" of the sampling frequency.


Second, optimized dither makes the output of the DAC --
which is, strictly speaking, digital -- look like an analog
signal with random noise.


The counterpoint is that virtually every real world audio signal has
enough noise to dither itself. Enough of it comes from the analog
domain, which just isn't that clean compared to 16 bits.


I'm not sure this is correct. But I'm not going to argue the point before
doing some checking.


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On Wed, 21 Mar 2012 15:27:00 -0700, "William Sommerwerck"
wrote:

"Arny Krueger" wrote in message
m...
"William Sommerwerck" wrote in message
...


There are two good reasons for dither.


First, it prevents obvious distortion when a musical note is a
"sub-multiple" of the sampling frequency.


Second, optimized dither makes the output of the DAC --
which is, strictly speaking, digital -- look like an analog
signal with random noise.


The counterpoint is that virtually every real world audio signal has
enough noise to dither itself. Enough of it comes from the analog
domain, which just isn't that clean compared to 16 bits.


I'm not sure this is correct. But I'm not going to argue the point before
doing some checking.


If the recording has its source in a microphone, you can be pretty
sure that this is correct, and not by a small margin either. You need
the noise to be better than about 100dB below signal to prevent any
degree of natural dither. There certainly isn't a recording studio
that can achieve that. There is one sound lab I know that I believe
can - it is buried deep underground in an old salt mine.

d
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On Wed, 21 Mar 2012 09:57:28 -0700, ethanw wrote:

[ dither]

But it's not nearly as important as some people claim, at least not for
most music that's recorded at sensible levels.


Very likely.

However I remember going to a startling demonstration of what dither is
for, at an AES convention here in the UK somewhere around 1980. Some BBC
engineers did a demo rather like the part of your video where you
gradually reduce the number of bits used to digitise sound. They played a
piano recording truncated to only 4 bits, then the same but dithered. The
dither noise was like standing next to a steam engine, but the way the
piano notes decayed smoothly in to the noise compared with the crackling
and buzzes of the undithered version was very memorable.

Audio wasn't all often 16 bit then (The BBC used 12 bit and 14 bit
systems) and the dither/noise was arguably more likely to be audible.

--
Anahata
-+- http://www.treewind.co.uk
Home: 01638 720444 Mob: 07976 263827


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William Sommerwerck writes:

It costs nothing to properly dither the signal. Therefore, there's no reason
not to do it.


If dithering makes no difference in the final result, then there is no reason
to waste time or energy to do it, however small the required time or energy
might be (it is never zero). However ... if it makes no difference in the
final result, there's no harm in doing it, either.

The reason that an undithered signal /doesn't/ sound awful, is that musical
tones are rarely at (or close-enough to) sub-multiples of the sampling
frequency, and/or don't last long enough, for correlated quantization error
to be audible.


I've listened to Ethan's test files, and I hear no difference. If I hear no
difference, there isn't any, or at least none that is worth worrying about,
provided that the recording is intended to be heard (and not analyzed by a
computer or something).

To hear what this error sounds like, listen to a test CD with an undithered
sweep tone. (I think the Denons are undithered, but I don't remember.)


I don't have one. But if a sweep tone is required to hear the difference, then
it doesn't matter, because none of my recording projects involve sweep tones.
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"William Sommerwerck" wrote in message
...
I met someone about 10 years ago whose living room could have been
a showroom for all that snake oil. For basically a CD player,
amplifier,
pair of speakers, and connecting cables, he had spent almost $300K.
And it was all nonsense because his room was so sonically poor,
and the building A/C contributed a ton of uncontrollable noise.
He had even managed to pipe in his own dedicated power supply
so he could avoid the "noisy" standard power from his outlets.


Yep, I have a friend who was/is like that. He's calmed down quite a
bit after I've told him what matters and what doesn't. He initially
didn't
even have a grounded AC outlet in his room. I installed one for him.
He used to put arrows on his connecting cables so he could install
them in the same direction because "that was the way they were
burned in". He'd change out the power cables to some upgraded stuff.
He had a different set of inter-connects for classical and another for
jazz and another for vocals. It was crazy just trying to listen to music
at his house. I got a lot of my "high end" stuff from him because he
was constantly trading pieces out. I'd get stuff I could never afford at
rock bottom prices or for free. In reality, everything he did, did
something. It was subtle and you'd have to debate wether the $300
cable was $270 better than the $30 cable. But, I have to admit, things
did change, for better or worse, with all the tweaks he did.

Unfortunately,
he ended up listening to the equipment instead of the music.


The irony is that one buys high-quality equipment because it is
(supposedly) neutral -- rather than "musical" -- so that you can
appreciate
the performance, and ignore the hardware.



Nope, people pay that sort of money for bragging rights, nothing to do with
music or sound quality.

Trevor.


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"Anahata" wrote in message
o.uk...
But it's not nearly as important as some people claim, at least not for
most music that's recorded at sensible levels.


Very likely.

However I remember going to a startling demonstration of what dither is
for, at an AES convention here in the UK somewhere around 1980. Some BBC
engineers did a demo rather like the part of your video where you
gradually reduce the number of bits used to digitise sound. They played a
piano recording truncated to only 4 bits, then the same but dithered. The
dither noise was like standing next to a steam engine, but the way the
piano notes decayed smoothly in to the noise compared with the crackling
and buzzes of the undithered version was very memorable.



Right, dither is extremely CRITICAL in 4 bit systems! Even 8 bit ones :-)

Trevor.




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Trevor wrote:
: Nope, people pay that sort of money for bragging rights, nothing to do with
: music or sound quality.

Indeed, I remmeber that the brand name of his cables was "Statements".
Tells you something right there.

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"PStamler" wrote in message
...
It is alleged that even fairly benign speakers such as AR3s would force
the
protective circuits to react audibly.


AR3s weren't all that benign. First off, they had unusually low
sensitivity, meaning they needed more voltage than yer average speaker
to produce a given SPL.


Right. First off there wasn't just one AR3. The product's technical details
drifted somewhat even prior to the introduction of the AR3a. By modern
standards it was pretty efficient, but in a world that still had a lot of
604s, JBL component-series speakers with horns and high-effeciency woofers,
Altec Voice of the Theatre, and EV Patricians, they had low effciency and
low impedance.

Second, trey were nominally 4 ohms, in an era when 8 ohm speakers were
the norm, and they could dip down to 3 ohms at some frequencies,
meaning they also needed a lot of current to produce a given SPL.


If your standard for a woofer was a D130 or the LF half a 604, then the AR3
was pretty intimidating. But, there were some bad-boy speakers in those
days like the Quad, Janzen, KLH and Crown electrostats.

Finally, it was the beginning of the era when rock music was taken
seriously by audio fans, who had mostly listened to classical, jazz
and Persuasive Percussion.


Right. Since you and I both lived then we know that part of the Command
Records formula was lots of mid-bass and midrange, but no real bass. The
politely- played string bass and drum kits on most jazz recordings were also
light on real bass.

In his excellent book on solid-state power
amp design, Bob Cordell discusses how repeated low-frequency signals
(read: kickdrum hits) can interact with the back-EMF from an
underdamped woofer (the AR speakers had a Qtc of 1.1, meaning they
were mildly underdamped) to make the speaker draw a good deal more
current than its nominal impedance rating would imply. The AR3s, when
hit by kickdrum-type signals, demanded current levels corresponding to
an effective load impedance of 1-1.5 ohms.


There were some odd nonlinear things that happened when voice coils were
forced out of the magnetic field and then suddenly popped back in. A voice
coil out of its magnetic field generates no counter-EMF, and so its
impedance is very low - basically DCR. Negative resistance effects are
possible with highly nonlinear loads.

Most of the craze for super-powered amplifiers in the 1970s (think
Phase Linear, Ampzilla, etc.) was fueled by the desire to drive AR-
type speakers to high volumes on rock music. It took a while for folks
to realize that current delivery mattered more than raw power, and
that an amp which voltage-clipped at, say, 100W (but with ample
current capability) could do as well as a "700W" amplifier. I have
such an amp (from Parasound) in the other room, and it will drive just
about anything happily. Doesn't burn up, either.


Things really changed rapidly across those days. Tubed amps could be hurt by
running hard open-circuited, but shorts and low impedance loads didn't seem
to really bother them much. A really huge tubed amp was 60 wpc. Many of the
second generation SS amps started at 30-40 watts and ran up to 150-350 wpc.
Some could be killed instantly by a hard short. I fried an early Heathkit SS
amp with my roomates AR-3s.

Push on a speaker harder, and it fights back harder. AFAIK the SOA of a
tube is near-infinite, while the SOA of the early SS power devices was a bad
joke. The big amps of the day had half or less the SOA than modern amps
with the same power output. Development of SS devices that could handle big
reactive loads was stimulated by automotive electronic ignition systems and
computer hard drive voice coil drivers.




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"William Sommerwerck" wrote in message
...
"Arny Krueger" wrote in message
...
"William Sommerwerck" wrote in message
...


There are two good reasons for dither.


First, it prevents obvious distortion when a musical note is a
"sub-multiple" of the sampling frequency.


Second, optimized dither makes the output of the DAC --
which is, strictly speaking, digital -- look like an analog
signal with random noise.


The counterpoint is that virtually every real world audio signal has
enough noise to dither itself. Enough of it comes from the analog
domain, which just isn't that clean compared to 16 bits.


I'm not sure this is correct. But I'm not going to argue the point before
doing some checking.


Funny story that involves your good buddy Mr. JA. He wrote a glowing SP
review of a Meridian ADC with selectable dither, centerpieced by his
experiences transcribing one of his analog master tapes. In his sighted
evaluations he seemed to find a different poetic description of every
different dither that the Meridian added. I did a little study of the
situation and found that as a rule, the analog tape had 10s of dB more
noise, even on an fractional-octave basis.


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Mxsmanic wrote:

Not long ago I got into an argument of sorts on another forum with someone who
insisted that YouTube was dramatically, criminally distorting the sound of the
music he played in a video. After I expressed doubts on the degree of
distortion that YouTube's encoding and compression might cause, he finally
sent me sound files of the original recording and the YouTube recording. I
couldn't hear a difference, but I was flamed in the most arrogant way
imaginable for daring to say so. So I took the files again into Sound Forge
and nulled them in the same way shown in this video. The result was silence
... which means, objectively, that there was no significant difference between
the YouTube version of the music recording and the original. I even looked at
the waveform resulting from the nulling, and it was essentially flat right
down to individual samples (a maximum amplitude of perhaps 2-4, out of
16,777,216). So obviously this guy was blowing smoke, but I could not convince
him of that.


I suggest you actually try this instead of just pretending to have done
so. Take an uncompressed file like a .wav, put it into a video container
file and upload it. What comes back won't be anything like what you sent
up.

What's interesting is that the same thing is apt to happen to the video
as well as to the audio. Youtube uses perceptual encoding for both, so
for they audio they basically throw away anything that the algorithm thinks
won't be audible. What gets thrown away is between 70% and 90% of the
actual data stream going up if you're sending up uncompressed audio.

It's worse if you send up a typical MP3 file that has already been through
a perceptual encoding stage because the artifacts are made much worse by
transcoding.

The only way to get an absolute copy as you describe is to upload a data file
in the precise format that Youtube uses for internal representation, so that
no encoding or transcoding is required. This format is documented (and in
fact, Final Cut Pro has a specific setting for generating youtube files).
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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"Anahata" wrote in message
o.uk...
On Wed, 21 Mar 2012 09:57:28 -0700, ethanw wrote:

[ dither]

But it's not nearly as important as some people claim, at least not for
most music that's recorded at sensible levels.


Very likely.

However I remember going to a startling demonstration of what dither is
for, at an AES convention here in the UK somewhere around 1980. Some BBC
engineers did a demo rather like the part of your video where you
gradually reduce the number of bits used to digitise sound. They played a
piano recording truncated to only 4 bits, then the same but dithered. The
dither noise was like standing next to a steam engine, but the way the
piano notes decayed smoothly in to the noise compared with the crackling
and buzzes of the undithered version was very memorable.


That demo makes its point well, but it doesn't apply well to modern
recording for the reason that Don just brought up.

Audio wasn't all often 16 bit then (The BBC used 12 bit and 14 bit
systems) and the dither/noise was arguably more likely to be audible.


In practice, 12 bits is where adding dither becomes just about manditory,
and if you are down at 8 bits or less, there is no choice but to use it and
your choices about noise shaping become very important.

BTW dither has been around for a long time in purely analog systems. It can
do wonders for the listenability of a slightly misadjusted class B power
amp, for example. Of course in modern times, we don't have them to worry
about. ;-)



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"William Sommerwerck" wrote in message
...
"Mxsmanic" wrote in message
...
anahata writes:


I obviously don't know the technical details of your story, but my
first reaction would be to question whether what you get when you
download a YouTube video (for comparison with the "original") is
exactly what you get when you play it in real time.


I was going by the audio files he gave me, and he claimed that there
was a huge, horrible difference between them. I did the nulling test
and found essentially no difference at all, and I trust the numbers
more than I trust his ear or his ego.


I think YouTube probably adopted the same position that I did. You
can't fix something that isn't broken.


As for Ethan's "Audio Myths" video, I saw that a couple of weeks
ago and there's a lot of good stuff there, though I'm not sure sure
everyone would agree with his views about the (un)importance of
dither.


If I understand dither correctly, then his assertion that it isn't
important seems reasonable.


It costs nothing to properly dither the signal. Therefore, there's no
reason
not to do it.


The reason that an undithered signal /doesn't/ sound awful, is that
musical
tones are rarely at (or close-enough to) sub-multiples of the sampling
frequency, and/or don't last long enough, for correlated quantization
error
to be audible.


If you work with systems that really do require dither, the above
considerations don't seem to hold much water IME. The odd collection of
noises that you can get with music has to be heard to be believed.

The two reasons that undithered signals don't sound awful in modern systems
is:

(1)Whatever nasty sounds they make are limited to to 1 or 2 LSB, and in 16
bit systems they are very, very small
(2) Self-dither - the analog domain sources we use diigital with have noise
on the order of 10 LSBs or more. (thats 10x 1 LSB, not the 10 lowest bits).

To hear what this error sounds like, listen to a test CD with an
undithered
sweep tone. (I think the Denons are undithered, but I don't remember.)


Not a bad do it yourself project for most DAW software users.


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"Arny Krueger" wrote in message
...
"William Sommerwerck" wrote in message
...


The counterpoint is that virtually every real-world audio signal
has enough noise to dither itself. Enough of it comes from the
analog domain, which just isn't that clean compared to 16 bits.


I'm not sure this is correct. But I'm not going to argue the point
before doing some checking.


Funny story that involves your good buddy, Mr. JA.


I hope you mean that sarcastically. John is no more my "good buddy" than you
are.


He wrote a glowing SP review of a Meridian ADC with selectable dither,
centerpieced by his experiences transcribing one of his analog master
tapes. In his sighted evaluations he seemed to find a different poetic
description of every different dither that the Meridian added. I did a

little
study of the situation and found that as a rule, the analog tape had tens
dB more noise, even on an fractional-octave basis.


So... are you agreeing or disagreeing with me?

The purpose of dither is to sufficiently randomize the quantization error
that it's no longer correlated with the signal. This requires noise with a
P-P value of two quantization steps (I think). The background noise of an
analog signal is unlikely to be at this level.




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On 3/21/2012 3:00 PM, Mxsmanic wrote:

I think YouTube probably adopted the same position that I did. You can't fix
something that isn't broken.


But a lot of people try to do just that.



--
"Today's production equipment is IT based and cannot be
operated without a passing knowledge of computing, although
it seems that it can be operated without a passing knowledge
of audio." - John Watkinson

http://mikeriversaudio.wordpress.com - useful and
interesting audio stuff
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Arny Krueger wrote:

Funny story that involves your good buddy Mr. JA. He wrote a glowing SP
review of a Meridian ADC with selectable dither, centerpieced by his
experiences transcribing one of his analog master tapes. In his sighted
evaluations he seemed to find a different poetic description of every
different dither that the Meridian added. I did a little study of the
situation and found that as a rule, the analog tape had 10s of dB more
noise, even on an fractional-octave basis.


It's weird, though. With the Prism AD-124, as I go around with different
noise shaping patterns, I can hear slight tonal differences in the
program audio, even recording at levels where the noise floor should make
no difference at all.

I don't know why I hear the tonal differences, and I think the flat Gaussian
dither gives the most neutral effect, but it's audible in a single-blind
test.

This may well be an artifact of the converter, but if so it's a really
interesting one.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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Scott Dorsey writes:

I suggest you actually try this instead of just pretending to have done
so.


I actually tried it.

Take an uncompressed file like a .wav, put it into a video container
file and upload it. What comes back won't be anything like what you sent
up.


I was comparing the files he sent me, which he said were the original and the
YouTube versions. If they were truly what he told me they were, there was no
significant degradation in the YouTube audio.

What's interesting is that the same thing is apt to happen to the video
as well as to the audio. Youtube uses perceptual encoding for both, so
for they audio they basically throw away anything that the algorithm thinks
won't be audible. What gets thrown away is between 70% and 90% of the
actual data stream going up if you're sending up uncompressed audio.


That's how all lossy compression for audio and video generally works these
days. Otherwise YouTube would not be able to compressed video by nearly 500 to
1 with so few artifacts.

The only way to get an absolute copy as you describe is to upload a data file
in the precise format that Youtube uses for internal representation, so that
no encoding or transcoding is required. This format is documented (and in
fact, Final Cut Pro has a specific setting for generating youtube files).


As I've said, he sent me the files directly; YouTube was not involved (at
least at my end).
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"William Sommerwerck" wrote in message
...
"Arny Krueger" wrote in message
...
"William Sommerwerck" wrote in message
...


The counterpoint is that virtually every real-world audio signal
has enough noise to dither itself. Enough of it comes from the
analog domain, which just isn't that clean compared to 16 bits.


I'm not sure this is correct. But I'm not going to argue the point
before doing some checking.


Funny story that involves your good buddy, Mr. JA.


I hope you mean that sarcastically. John is no more my "good buddy" than
you
are.


He wrote a glowing SP review of a Meridian ADC with selectable dither,
centerpieced by his experiences transcribing one of his analog master
tapes. In his sighted evaluations he seemed to find a different poetic
description of every different dither that the Meridian added. I did a

little
study of the situation and found that as a rule, the analog tape had tens
dB more noise, even on an fractional-octave basis.


So... are you agreeing or disagreeing with me?

The purpose of dither is to sufficiently randomize the quantization error
that it's no longer correlated with the signal. This requires noise with a
P-P value of two quantization steps (I think) The background noise of an
analog signal is unlikely to be at this level.


Right, analog tape will be FAR more for 16 bit recordings :-)

Trevor.


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So... are you agreeing or disagreeing with me?

The purpose of dither is to sufficiently randomize the quantization error
that it's no longer correlated with the signal. This requires noise with a
P-P value of two quantization steps (I think). The background noise of an
analog signal is unlikely to be at this level.


No, it doesn't require that level of noise exactly, it requires that
level as a MINIMUM. That amount of noise OR MORE will properly dither
the quantization.

Mark


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Mark writes:

No, it doesn't require that level of noise exactly, it requires that
level as a MINIMUM. That amount of noise OR MORE will properly dither
the quantization.


It sounds like you're just trading one noise for another. Since it is noise
either way, what's the advantage, particularly if it is inaudible?
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"Mark" wrote in message
...
The purpose of dither is to sufficiently randomize the quantization error
that it's no longer correlated with the signal. This requires noise with
a
P-P value of two quantization steps (I think). The background noise of an
analog signal is unlikely to be at this level.


No, it doesn't require that level of noise exactly, it requires that
level as a MINIMUM. That amount of noise OR MORE will properly dither
the quantization.


It doesn't even require a "minimum" 2 bits P-P, but more, as with most
analog sources, will do the job fine.

Trevor.


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On Tue, 20 Mar 2012 04:08:47 -0700, Luxey wrote
(in article
24504044.276.1332241727760.JavaMail.geo-discussion-forums@vbmf37):

No, he did research for best trolling themes. Next from him will be
vinyl vs. CD, digital vs. analog, overcompression and loudness wars,...
------------------------------snip------------------------------


I'm waiting for somebody to bring up religion.

Can't somebody just yell "HITLER" and get back to real conversations?

--MFW

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On Tue, 20 Mar 2012 21:14:50 -0700, wrote
(in article ):

I met someone about 10 years ago whose living room could have been a
showroom for all that snake oil. For basically a CD player, amplifier,
pair of speakers, and connecting cables, he had spent almost $300,000.
And it was all nonsense because his room was so sonically poor,
and the building A/C contributed a ton of uncontrollable noise.
He had even managed to pipe in his own dedicated power supply
so he could avoid the "noisy" standard power from his outlets.
------------------------------snip------------------------------


Gordon Holt of STEREOPHILE told me on several occasions that he felt that
room acoustics were the single biggest factor that could help or hinder sound
quality. Unfortunately, there's no way to package room acoustics and sell
them for $99.95 (more like $995.95) like you can an expensive cable. Holt
was dismayed and unhappy that so few people grasped the importance of the
room itself.

I've also been to some very wealthy homes that had very costly audio and/or
home theater systems, but their acoustical properties were so bad, it was a
pain to listen to -- marble floors, reflective walls, high ceilings, tons of
reverb, weird nodes... just a sonic disaster. But they had all the right
gear. Nobody apparently told them to redecorate... or they just were
determined to keep the room itself the same.

--MFW

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On Thu, 22 Mar 2012 06:00:40 -0700, Scott Dorsey wrote
(in article ):

What's interesting is that the same thing is apt to happen to the video
as well as to the audio. Youtube uses perceptual encoding for both, so
for they audio they basically throw away anything that the algorithm thinks
won't be audible. What gets thrown away is between 70% and 90% of the
actual data stream going up if you're sending up uncompressed audio.

It's worse if you send up a typical MP3 file that has already been through
a perceptual encoding stage because the artifacts are made much worse by
transcoding.
------------------------------snip------------------------------


Yep, that's what I see and hear, too. Horrific compression for sound and
picture. I would agree with a previous comment that they don't seem to crush
the 720P HD videos as much, depending on the source.

--MFW



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William Sommerwerck William Sommerwerck is offline
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The purpose of dither is to sufficiently randomize the quantization
error that it's no longer correlated with the signal. This requires
noise with a P-P value of two quantization steps (I think). The
background noise of an analog signal is unlikely to be at this level.


No, it doesn't require that level of noise exactly, it requires that
level as a MINIMUM. That amount of noise OR MORE will properly
dither the quantization.


This Bothers Me. My gut reaction is No, that's not right. Noise at that
level "looks like" part of the signal. How can it properly randomize the
quantization errors?

For the time being, I remain unconvinced.


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"William Sommerwerck" wrote in message
...
"Arny Krueger" wrote in message
...
"William Sommerwerck" wrote in message
...


The counterpoint is that virtually every real-world audio signal
has enough noise to dither itself. Enough of it comes from the
analog domain, which just isn't that clean compared to 16 bits.


I'm not sure this is correct. But I'm not going to argue the point
before doing some checking.


Funny story that involves your good buddy, Mr. JA.


I hope you mean that sarcastically. John is no more my "good buddy" than
you
are.


He wrote a glowing SP review of a Meridian ADC with selectable dither,
centerpieced by his experiences transcribing one of his analog master
tapes. In his sighted evaluations he seemed to find a different poetic
description of every different dither that the Meridian added. I did a

little
study of the situation and found that as a rule, the analog tape had tens
dB more noise, even on an fractional-octave basis.


So... are you agreeing or disagreeing with me?

The purpose of dither is to sufficiently randomize the quantization error
that it's no longer correlated with the signal. This requires noise with a
P-P value of two quantization steps (I think).


So far so good.

The background noise of an analog signal is unlikely to be at this level.


It is likely to be this high or appreciably higher almost all of the time.

William, you need some time in the real world, actually looking at recorded
signals and signals at the output of a mic preamp or even just the mic.




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"Mxsmanic" wrote in message
...
Mark writes:

No, it doesn't require that level of noise exactly, it requires that
level as a MINIMUM. That amount of noise OR MORE will properly dither
the quantization.


It sounds like you're just trading one noise for another. Since it is
noise
either way, what's the advantage, particularly if it is inaudible?


Quantization noise related to real world audio signals is both coherent and
represents aharmonic distortion. IOW, nasty sounding and audible if anything
that level is audible. Not easily masked.

Normal random noise of the same level is always preferable. The noise
related to dither can be spectrally shaped so that it is far less noticeable
than red, pink or white noise of the same amplitude.


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"William Sommerwerck" wrote in message
...
The purpose of dither is to sufficiently randomize the quantization
error that it's no longer correlated with the signal. This requires
noise with a P-P value of two quantization steps (I think). The
background noise of an analog signal is unlikely to be at this level.


No, it doesn't require that level of noise exactly, it requires that
level as a MINIMUM. That amount of noise OR MORE will properly
dither the quantization.


This Bothers Me. My gut reaction is No, that's not right. Noise at that
level "looks like" part of the signal. How can it properly randomize the
quantization errors?


William, you don't seem to understand that when dither is properly added, it
hits the quantizer looking just like the rest of the signal. I would chalk
that up to a failure of logic.

With a lot of DAW software and stand alone resamplers, you can turn dither
off during conversions that should have it.

I've confirmed experimentally that adding identical noise to the signal
before conversion has the effect as turning on the dither.

I don't know if you read my earlier post about dither helping sound quality
in pure analog systems, like class B amplifiers with the bias slightly
misadjusted. If so, you missed its meaning.


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Marc Wielage wrote:

Yep, that's what I see and hear, too. Horrific compression for sound and
picture. I would agree with a previous comment that they don't seem to crush
the 720P HD videos as much, depending on the source.


On the video side there are some interesting tricks that you can play.

For example, these two films were shot similarly, and transferred identically:

http://www.youtube.com/watch?v=2s1w3WlsTR0

http://www.youtube.com/watch?v=C4gDmdKXatE

Just watch the opening countdown leader to see the difference.
One of these was uploaded as a standard Pro-Res file, the other was a
similar Pro-Res file encoded with the FCP "Youtube" preset.
--scott

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


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"Arny Krueger" wrote in message
...

The purpose of dither is to sufficiently randomize the quantization error
that it's no longer correlated with the signal. This requires noise with

a
P-P value of two quantization steps (I think).


So far so good.


The background noise of an analog signal is unlikely to be at this level.


It is likely to be this high or appreciably higher almost all of the time.


That was my point.


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"Arny Krueger" wrote in message
...
"William Sommerwerck" wrote in message
...


The purpose of dither is to sufficiently randomize the quantization
error that it's no longer correlated with the signal. This requires
noise with a P-P value of two quantization steps (I think). The
background noise of an analog signal is unlikely to be at this level.


No, it doesn't require that level of noise exactly, it requires that
level as a MINIMUM. That amount of noise OR MORE will properly
dither the quantization.


This Bothers Me. My gut reaction is No, that's not right. Noise at that
level "looks like" part of the signal. How can it properly randomize the
quantization errors?


William, you don't seem to understand that when dither is properly added,
it hits the quantizer looking just like the rest of the signal. I would

chalk
that up to a failure of logic.


Not at all. I understand that. See below. One of my points is that how noise
that is comparable in level to the signal itself randomize quantization
errors that are much lower in level?


I've confirmed experimentally that adding identical noise to the signal
before conversion has the effect as turning on the dither.


Well, of course! That isn't the issue. The issue is whether /high levels/ of
background noise produce the same dithering effect as (supposedly)
theoretically "correct", optimized values.


I don't know if you read my earlier post about dither helping sound

quality
in pure analog systems, like class B amplifiers with the bias slightly
misadjusted. If so, you missed its meaning.


No, I got it.

I am not agreeing or disagreeing. I simply want to see a clear explanation.


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петак, 23. март 2012. 16.52.12 UTC+1, William Sommerwerck је написао/ла:
Not at all. I understand that. See below. One of my points is that how noise
that is comparable in level to the signal itself randomize quantization
errors that are much lower in level?


Seams your question is if the low level signal is actually dithering higher level noise, instead of being vice versa?
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On Friday, March 23, 2012 5:04:29 AM UTC-4, Marc Wielage wrote:
Unfortunately, there's no way to package room acoustics and sell
them for $99.95 (more like $995.95) like you can an expensive cable.


Well, some expensive cables sell for $5,000 each, and you can buy a room full of great acoustic treatment for the cost on a stereo pair of wires like that.

Holt was dismayed and unhappy that so few people grasped the importance of
the room itself.


I'm dismayed too.

I've also been to some very wealthy homes that had very costly audio and/or
home theater systems, but their acoustical properties were so bad, it was a
pain to listen to -- marble floors, reflective walls, high ceilings, tons of
reverb, weird nodes... just a sonic disaster. But they had all the right
gear. Nobody apparently told them to redecorate... or they just were
determined to keep the room itself the same.


I think it's mainly ignorance, and also being brainwashed by audio salespeople and magazines. Yes, I've been told more than once "I don't want my living room to look like a recording studio" and I understand that. But if someone has $100k invested in "gear" and doesn't have a dedicated room, or doesn't care enough to obtain what their system is capable of, their priorities are really screwed up IMO.

--Ethan
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"Luxey" wrote in message
news:23826693.1455.1332518730099.JavaMail.geo-discussion-forums@vbtv42...
?????, 23. ???? 2012. 16.52.12 UTC+1, William Sommerwerck ?? ???????/??:

Not at all. I understand that. See below. One of my points is how
can noise that is comparable in level to the signal itself randomize
quantization errors that are much lower in level?


Seams your question is if the low level signal is actually dithering
higher level noise, instead of being vice versa?


I don't think so. Wouldn't truly random noise not require dither? Wouldn't
it be self-dithering?




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William Sommerwerck wrote:
"Luxey" wrote in message
news:23826693.1455.1332518730099.JavaMail.geo-discussion-forums@vbtv42...
?????, 23. ???? 2012. 16.52.12 UTC+1, William Sommerwerck ??
???????/??:

Not at all. I understand that. See below. One of my points is how
can noise that is comparable in level to the signal itself randomize
quantization errors that are much lower in level?


Seams your question is if the low level signal is actually dithering
higher level noise, instead of being vice versa?


I don't think so. Wouldn't truly random noise not require dither?
Wouldn't it be self-dithering?

I don't think it's useful to conflate dithering and "random noise". White
and pink noise, can be affected by different dithering alogorithms, for
example. One may have a difficult time *hearing* the impact of dither on
noise, but it these days it can be proven beyond any doubt simply by
comparing samples.

--
best regards,

Neil





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William Sommerwerck wrote:
The purpose of dither is to sufficiently randomize the quantization
error that it's no longer correlated with the signal. This requires
noise with a P-P value of two quantization steps (I think). The
background noise of an analog signal is unlikely to be at this level.


No, it doesn't require that level of noise exactly, it requires that
level as a MINIMUM. That amount of noise OR MORE will properly
dither the quantization.


This Bothers Me. My gut reaction is No, that's not right. Noise at that
level "looks like" part of the signal. How can it properly randomize the
quantization errors?


It doesn't matter if it's part of the signal. If you do something like
this, the noise floor will not be properly reproduced but signals above the
noise floor probably will be.

For the time being, I remain unconvinced.


Dither is a good idea and it doesn't hurt to use it.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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On 3/23/2012 4:57 AM, Marc Wielage wrote:
On Tue, 20 Mar 2012 04:08:47 -0700, Luxey wrote
(in article
24504044.276.1332241727760.JavaMail.geo-discussion-forums@vbmf37):

No, he did research for best trolling themes. Next from him will be
vinyl vs. CD, digital vs. analog, overcompression and loudness wars,...
------------------------------snip------------------------------


I'm waiting for somebody to bring up religion.

Can't somebody just yell "HITLER" and get back to real conversations?

--MFW

As I understand the law, the thread needs to evolve
to that point, and forcing the point is a violation.
[YMMV]
==

Later...
Ron Capik
--
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"Scott Dorsey" wrote in message
...
William Sommerwerck wrote:


For the time being, I remain unconvinced.


Dither is a good idea and it doesn't hurt to use it.


I said that!

The issue is whether the noise already in a signal -- regardless of level --
automatically dithers it. I don't believe it does. I would to see an
explanation that goes beyond hand-waving.


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On Fri, 23 Mar 2012 12:52:11 -0700, "William Sommerwerck"
wrote:

"Scott Dorsey" wrote in message
...
William Sommerwerck wrote:


For the time being, I remain unconvinced.


Dither is a good idea and it doesn't hurt to use it.


I said that!

The issue is whether the noise already in a signal -- regardless of level --
automatically dithers it. I don't believe it does. I would to see an
explanation that goes beyond hand-waving.


Dither is simply noise that is added to the signal, so it is there
ready when the quantization occurs. It matters not a jot how long
before quantization the noise got there. If it is added at the
microphone, it is exactly the same as if it was added a nanosecond
before quantization. All that matters is that it is a signal free from
correlation. Noise, in other words.

Remember it does not remove the energy associated with quantization
artefacts - it simply spreads that energy across the audio band.

d
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