MOTM

Okay, a few people are going to say I am nuts for saying this, but 
it`s one of the major reasons for some of its inefficiencies.

THE DISCS ARE NOT PERFECTLY ROUND. 

When the discs come out of the factory, they look round,but they are 
far from round. This creates a push-pull wobble effect. 

I have done blind listening tests with the same discs. One of them is 
the factory version and the other is a perfectly round bevelled disc.
I heard information on the bevelled disc which was missing from the 
factory disc. Don`t believe any of the AudioFools who say it doesn`t 
make a difference. Any person who can hear properly, can spot the 
difference right away. It`s amazing, that the manufacturers let this 
happen in the first place. Even AudioFool CD`s aren`t bevelled.

The reason, I didn`t answer this question more quickly, was that i 
couldn`t find the website for you to see for yourself. The bevelling 
machine comes from Germany.

There are DAC`s out there, that don`t use any filtering whatsoever.
Please check out the URL below.

http://www.sakurasystems.com/articles/pitracermemo.html

This is a Japanese company, which is way ahead of the game. Instead 
of fixing the Digital to Analog converter with filtering and 
oversampling, they choose to attack the problem at its source. They 
keep parts, in the units, down to the bare minimum to get the job 
done. 

Regards,
RM

> I have done blind listening tests with the same discs. One of them is
> the factory version and the other is a perfectly round bevelled disc.
> I heard information on the bevelled disc which was missing from the
> factory disc. Don`t believe any of the AudioFools who say it doesn`t
> make a difference. Any person who can hear properly, can spot the
> difference right away. It`s amazing, that the manufacturers let this
> happen in the first place. Even AudioFool CD`s aren`t bevelled.

Either the data is read correctly or it isn't. Data is buffered as much as
a second ahead of where it is with plenty of time to recover. If you have
exactly the same data with no buffer underrun, wobble or no wobble, it
will make no difference.

It amazes me that there are those that think that regular audio CD players
can't do something CDROM players on computers do on a daily basis.

-->Neil

-------------------------------------------------------------------------------
Neil Bradley            In the land of the blind, the one eyed man is not
Synthcom Systems, Inc.  king - he's a prisoner.
ICQ #29402898

Neil writes:
>>Either the data is read correctly or it isn't. Data is buffered as much as
a second ahead of where it is with plenty of time to recover. If you have
exactly the same data with no buffer underrun, wobble or no wobble, it
will make no difference.<<

I was thinking the same thing. A wobbly 1 or 0 is still a 1 or 0. Unless data 
is being dropped or lost because of the wobble, there will be no sound 
difference.

When CD's hit the market years ago, Computer Music Journal had an article 
showing that the digital data affected listeners. People grew weaker and were 
not able to lift as much weight when listening to a CD as opposed to a vinyl 
record. How ridiculous, considering the CD output is filtered and appears as a 
continuous analog signal at the output.

-Elhardt

--- In motm@y..., Neil Bradley <nb@s...> wrote:
> > I have done blind listening tests with the same discs. One of 
them is
> > the factory version and the other is a perfectly round bevelled 
disc.
> > I heard information on the bevelled disc which was missing from 
the
> > factory disc. Don`t believe any of the AudioFools who say it 
doesn`t
> > make a difference. Any person who can hear properly, can spot the
> > difference right away. It`s amazing, that the manufacturers let 
this
> > happen in the first place. Even AudioFool CD`s aren`t bevelled.
>
 
> Either the data is read correctly or it isn't. 

You just said it yourself, it doesn`t matter if it is buffered or 
not,if it wasn`t read propeply to begin with.

Your average Consumer CD player has approx. 4000 errors per second. A 
HiFi player cuts it down by about half. AudioPhile and Pro Gear 
brings down the error count to below 1000.



Data is buffered as much as
> a second ahead of where it is with plenty of time to recover.


Recover from what, the hit your portable CD or Automobile CD player 
took to avoid skips. :) For Data CD`s it doesn`t matter as much, but 
for audio, it matters a lot.


 If you have
> exactly the same data with no buffer underrun, wobble or no wobble, 
it
> will make no difference.

Sorry, but this statement is wrong. please read the Article with the 
attached Url`s

 
> It amazes me that there are those that think that regular audio CD 
players
> can't do something CDROM players on computers do on a daily basis.
> 

What amazes me, is Designers inventing New Formats, when they haven`t 
figured how to make the most out of the one that is there now.

This is all tongue and cheek stuff, at the end of the day, the 
question remains, does it sound good or not

Regards,
RM


> -->Neil
> 
> --------------------------------------------------------------------
-----------
> Neil Bradley            In the land of the blind, the one eyed man 
is not
> Synthcom Systems, Inc.  king - he's a prisoner.
> ICQ #29402898

> For Data CD`s it doesn`t matter as much, but 
> for audio, it matters a lot.

I disagree.  If *one* zero is interpreted as a one on a data CD, it 
could screw up the whole program, if it's an executable.  Data CDs 
are much less forgiving; with audio, our ear integrates.

I think.

Mike

--- In motm@y..., elhardt@a... wrote:
> Neil writes:
> >>Either the data is read correctly or it isn't. Data is buffered 
as much as
> a second ahead of where it is with plenty of time to recover. If 
you have
> exactly the same data with no buffer underrun, wobble or no wobble, 
it
> will make no difference.<<


> 
> I was thinking the same thing. A wobbly 1 or 0 is still a 1 or 0. 
Unless data 
> is being dropped or lost because of the wobble, there will be no 
sound 
> difference.

The problem is caused by the wobble, thereby creating an error. Since
you have lost the bit in question, you can not recover it. Now 
imagine this process taking place about 2000 to 4000 times in one 
second and tell me it doesn`t affect the outcome of the sound.

> 
> When CD's hit the market years ago, Computer Music Journal had an 
article 
> showing that the digital data affected listeners. People grew 
weaker and were 
> not able to lift as much weight when listening to a CD as opposed 
to a vinyl 
> record.

Was that Qualitative or Quantative Research :)


Guys, please Read the articles with the URL`s .  They are really 
informative and dispell a few myths. I will post another set of 
links  about this stuff in another post.

Regards,
RM
 How ridiculous, considering the CD output is filtered and appears as 
a 

> continuous analog signal at the output.
> 
> -Elhardt

> Your average Consumer CD player has approx. 4000 errors per second.

That means that, assuming each of those "errors" are single samples, that
10% of the audio is destroyed. That's plainly absurd.

> A
> HiFi player cuts it down by about half. AudioPhile and Pro Gear
> brings down the error count to below 1000.

Flatly not true. I worked as a repair tech for a short stint on CD players
- many brands (Sony, Denon especially). Not too particularly high end,
either - roughly $200-$500 players - in 1988.

Part of the focus process for the laser was done through checking pulses
coming from the error correction circuitry. That is, one pulse = one block
had an error reading it off the disc. I'm sorry, but the standard
alignment and adjustment procedure required there be *NO* errors.

> Data is buffered as much as
> > a second ahead of where it is with plenty of time to recover.
> Recover from what, the hit your portable CD or Automobile CD player
> took to avoid skips. :)

That, and a misread can allow the disc to spin back around for it to be
reread.

> For Data CD`s it doesn`t matter as much, but
> for audio, it matters a lot.

Audio == data on a CD. There is no difference. Data CDs cannot contain
errors, so it absolutely must be possible to read a CD with less than 4000
errors per second, otherwise no program or data files would survive.
Doesn't this strike you as completely irrational - that somehow $30 CDROM
drives *CAN* do perfect data transfers, yet a $150 CD player *CAN'T*?

> > will make no difference.
> Sorry, but this statement is wrong. please read the Article with the
> attached Url`s

Already did. While it may appear rational on the surface, it's completely
baseless and the description is so high level that it can be applied to

Listen, I spent several years listening to "audiophiles" rave about the
increased listening quality of CD sound rings and marking the edges of
their CDs to make them sound better. It's all provably false and anyone
with even the first level of understanding of how it works knows it's
completely laughable.

Anyway, attempting to steer the ship back on topic, I have heard others
say that MOTM gear sounds "digital". I've heard a few of the VCO samples -
they don't sound digital. Clean perhaps, but not digital.

-->Neil

-------------------------------------------------------------------------------
Neil Bradley            In the land of the blind, the one eyed man is not
Synthcom Systems, Inc.  king - he's a prisoner.
ICQ #29402898

Both audio and data CDs contain some redundancy that allow correcting single
bit errors and detecting more serious errors.  Correcting a single bit error
should be undetectable audibly or in a data stream.  Data is also
distributed, to some extent, so that a dropout that would affect many bits
is spread out somewhat.

If an error more serious than that occurs, audio players will interpolate
between neighboring samples.  The distribution of the error means that the
interpolation will happen several times to single samples in different
places rather than having one audible pop several samples long.  For low
frequency signals interpolation is not too bad, of course it affects higher
frequencies more.

A data CD, obviously, cannot interpolate if the error-correction fails.  On
a computer, though, you can retry a read, which often works.  I'm not sure
if higher end CD players retry reads (if there's a buffer it would be
possible) but I expect consumer audio CD players don't.

                    ...Craig

----- Original Message -----

From: "Mike Marsh" <mmarsh@...>
To: <motm@yahoogroups.com>
Sent: Tuesday, November 05, 2002 8:53 PM
Subject: [motm] Re: digital source and its medium puzzle- the answer


> > For Data CD`s it doesn`t matter as much, but
> > for audio, it matters a lot.
>
> I disagree.  If *one* zero is interpreted as a one on a data CD, it
> could screw up the whole program, if it's an executable.  Data CDs
> are much less forgiving; with audio, our ear integrates.
>
> I think.
>
> Mike
>
>
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>

>The problem is caused by the wobble, thereby creating an error. Since
>you have lost the bit in question, you can not recover it.

You most certainly can. A CD contains redundant data, with which it 
performs error correction--just like every other digital information 
storage device.

Unless your disc is severely damaged, none of those "4000" errors 
gets to the DAC.

I suggest creating a CD and checking for errors yourself. I've done 
this, and there aren't any.
-- 


-----------------------------------------------------------------
Tim Walters : The Doubtful Palace : http://www.doubtfulpalace.com

Oh no.....!

next thing ya know it'll be Mac vs. PC.

e

In a message dated 11/5/02 10:59:47 PM Central Standard Time, 
ringmod45@... writes:

> The problem is caused by the wobble, thereby creating an error. Since
>  you have lost the bit in question, you can not recover it


 It's been 20 years since I've read about CD encoding technology, so can 
someone correct me if I'm wrong here?

 I seem to remember reading that the data on a CD is duplicated once or 
possibly twice on every disc. That way, is there is a loss of any data, the 
error correction tells the laser to go to one of the extra tracks to recover 
it. The chances of the same bits of data on both tracks being bad is very 
slim, so this takes care of most of the errors.

 Also, I seem to remember that the laser pickup is on a transport that moves 
up and down. There is a sensor and circuitry that determines how far away the 
disc is from the laser at any given point in time. It then physically moves 
the laser up and down to follow any movement of disc surface. This keeps the 
laser in focus on the disc surface to avoid loss of data.

 When data cannot be recovered, error correction then kicks in to the phase 
that Paul mentioned somewhere, and interpolates any lost data.

 For what it's worth, I used to work at a high end audio shop years ago. One 
of the guys from McIntosh (I think it was) came in to talk to us about the 
product line. To demonstate the integrity of the error correction on their CD 
players, he attached thin strips of masking tape (drafter's tape?) to the 
discs. He put them on one by one, radially across the surface of the CD. He 
got up to something like 6 or 8 strips until it caused noticeable problems 
with the music! This is pretty wild considering that each one of those strips 
of tape was about 1/8" thick. Comparing that to the size of each bit on the 
disc surface (forgot how many microns that is), you get an idea of how well 
the error correction works. This was 15+ years ago, so I'd assume there have 
even been more improvements since then. 

 Andrew

> Anyway, attempting to steer the ship back on topic,

Yes. When I start downloading my maibox via modem, and I see
how many mails will be coming in, I can guess there must have been
a popular, off-topic thread in one of the mailing lists, even before
they arrive.



> I have heard others say that MOTM gear sounds "digital".

This comes from a single person (and a few of his fans) who
pretends he cannot hear the difference between a sample playback
machine and a free running VCO. This person obviously
used the word "digital" in order to say something nasty.
I've wasted way too much time in discussion with that guy.

There was a time when "digital" was used as a positive attribute
to advertise "low-noise", "modern", whatever. While this
word has a well-defined technical meaning (using numbers for
data representation - "digits" are "fingers", for counting in integer
steps ...), it's also just a _word_, and as such it follows every
fashion of the people who use it.

Personally, I'm happy that my MOTM is analogue, and I'm happy that
my VL7 physical modelling synth is digital. (But I'm thinking a lot about
analogue physical modelling modules lately - I guess I must discuss this
with Paul some time (;->) )

JH.

> ----- Original Message -----
> From: jhaible <jhaible@...>
> Yes. When I start downloading my maibox via modem, and I see how many
mails will be coming in, I can guess there must have been a popular,
off-topic thread in one of the mailing lists, even before they arrive.

Hint hint

> (But I'm thinking a lot about analogue physical modelling modules lately -
I guess I must discuss this with Paul some time (;->) )

Oh yes. :)  Please do.

LH