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Colouring CDs Green

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James Pinakis

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Aug 5, 1990, 8:11:24 AM8/5/90
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[I'm not sure whether I should have cross-posted this to one of the urban
myth newsgroups. Maybe someone can tell me if it's all crap. ]

I've heard from a somewhat unreliable source that if one colours the outside
and inside edges of a CD with green (and I'm told it _has_ to be green
or else it won't work) permanant felt pen, the CD will "sound better"
and skip less. It's meant to have something to do with eliminating/reducing
reflected light. Has anyone else heard this, and if so is it from somewhere
more reliable than "the guy at the local hi-fi shop"? Has anyone tried it?
I tried it on some CDs that my ageing CD player jumps around on and managed
to convince myself that my CD player was able to find the start of tracks
more easily, but still jumped occasionally. But as for "sounding better"...

james
jam...@bison.cs.uwa.oz.au

Pogo Joe

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Aug 5, 1990, 1:39:24 PM8/5/90
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If that isn't the biggest bunch of crap I have heard since the "CD Soundrings"
Jeez! What are these "audiophiles" smoking? They are the most unscientific
religious group of bozos I can think of. I read about this in Car Audio, and
they mentioned that Stereophile endorsed the practice. Well, they just lost
any credit I had for them. I really think there is a psychological disorder
that all of these "audiophiles" suffer from. I am totally serious. Does any-
one know of any studies that have been done? There are so many bogus acc-
esories out there that these guys fall for and buy, like $100 1M patch cords,
"ribbon" speaker wire, $5,000 CD players, etc. I can't believe what these
guys believe. You could literally make a fortune just by preying on their
ignorance, and I guess that's why it keeps happening. I suppose there is no
fortune to be made in the green marker market, but I bet someone started it
as a joke, kind of like Teenage Mutant Ninja Turtles. And look how much money
that joke brought in. Anyways, I am sick of these bozos, and the bozos that
claim that vinyl is better than digital. The supposed goal of high end audio
is to faithfully reproduce live music, and if you add coloration, it is det-
rimental to the sound. Vinyl is not "different," it is inferior. Why can't
these guys get a grip on the scene. Oh well, enough of my bitching, I just
woke up. Keep your green markers as far away from your CD's as I am from
my old turntable.

-------------------------------------------------------------------------------
Jeff Axelrod | "If you chose not to decide, you still have made
| a choice" -Neil Peart, Rush ///
ja2...@uxa.cso.uiuc.edu | \XX/ AMIGAUSER
-------------------------------------------------------------------------------

logan shaw

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Aug 5, 1990, 1:40:46 PM8/5/90
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I know you asked not to hear about something a salesman at a local hi-fi
shop said, but this is what I heard there, so it ain't so bad.

We were listening to a CD which had a nasty spot on it. Sounded like a
piece of metal rattling. So, the salesman put some goop on it that makes
it reflect better and it helped a little. Then he went back and put some
green stuff around the edges and it help a little more. Overall, the CD
sounded fairly harsh to start with and when he was done, it sounded
noticeably better. Before this, I was a skeptic. I did not believe CD
treatments did _any_ good whatsoever. Now I believe they help a little,
at least for CD's that already have a problem.

All this leads me to an interesting question: in common practice, how
much of the data really _is_ misread off the CD? Since they are parity
checked (I hear), has anyone made a CD player that counts and displays
parity errors per second? It would be interesting to see how many errors
commonly happen and would help everybody judge whether CD treatments
are really necessary.


>james
>jam...@bison.cs.uwa.oz.au


============================================================================
"The machine minded material man Logan Shaw
desperately dreams of a brand new sedan. ls...@ccwf.cc.utexas.edu
Wlll he expect long lasting gain ========================
from a toy that will race then rust in the rain?" - elim Hall, Things Break

Alain Picard

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Aug 5, 1990, 3:38:07 PM8/5/90
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In article <35...@ut-emx.UUCP>, ls...@walt.cc.utexas.edu (logan shaw) writes...

>In article <jamesp.649858284@bison> jam...@wacsvax.uwa.oz (James Pinakis) writes:
>All this leads me to an interesting question: in common practice, how
>much of the data really _is_ misread off the CD? Since they are parity
>checked (I hear), has anyone made a CD player that counts and displays
>parity errors per second? It would be interesting to see how many errors
>commonly happen and would help everybody judge whether CD treatments
>are really necessary.

WHAT DIFFERENCE does it make how many errors are picked up by the
error checking circuit? That's precisely what it's there for!
You can make a mistake on every single bit, if you correct it,
you still have the same information. Not ONE BIT less.

It's the same as writing (computer) data on a magnetic tape.
In the writing and reading back process, there are many "errors"
which are corrected using the CRC algorithms, but in the end,
your data is PERFECTLY intact. (Believe me, you can tell when
the data is screwed up.)

We're off on another wild goose chase here with error checking
and ##$!@!* green paint!!! If you're worried about sound on
CD's, worry about why people don't know where to put their
$#^$%@!! microphones during the recording sessions!

Sincerely yours, one who thinks a lot of CD's DON'T
sound so bad after all (But then again, I also listen
to LP's from the 50's and 60's, so what do I know?)

Alain Picard

Craig Demel

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Aug 5, 1990, 5:34:13 PM8/5/90
to
hahahahahahahahahahahahahahahahahahahahahahahahhaahahahahahahahahahahahahahaha
hahahaahhaahahahahaahahahahahahahahahahahahaHAHAHAHAAHAHAHAHAHAHAHAHAHAHAHAHAHAHA
HAHAHAHAHAHAHAHAAHAHAHAHAHAHAHAHAHAHAHAHHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAAH
AHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA


HAHAHA HAHAHA AHAHAHAH
HAHAHA HAHAHA AHAH HAHA
HAHAHA HAHAHA AHAH HAHA
HAHAHAHAHAHAHAHAHAH AHAH HAHA
HAHAHAHAHAHAHAHAHAH HAHAHAHAHAHAHAHA
HAHAHAHAAHAHAHAHAHA HAHA HAHA
HAHAHA HAHAHA HAHA HAHA
HAHAHA HAHAHA HAHA HAHA
HAHAHA HAHAHA HAHA HAHA


(but seriously, folks, I'm really just trying to keep you poor noninitiates
from learning about this amazing new audio secret. That way I can REALLY laugh
my head off when Drew Kaplan offers green markers for 49.50 each.)

-craig

Andrew Koenig

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Aug 5, 1990, 11:40:15 PM8/5/90
to
In article <35...@ut-emx.UUCP>, ls...@walt.cc.utexas.edu (logan shaw) writes:

> All this leads me to an interesting question: in common practice, how
> much of the data really _is_ misread off the CD?

The design criterion for the system is 1 uncorrected error
per month of continuous playback.
--
--Andrew Koenig
a...@europa.att.com

Greg Harp

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Aug 5, 1990, 8:17:16 PM8/5/90
to
In article <35...@ut-emx.UUCP> ls...@walt.cc.utexas.edu (logan shaw) writes:
>I know you asked not to hear about something a salesman at a local hi-fi
>shop said, but this is what I heard there, so it ain't so bad.
>
>We were listening to a CD which had a nasty spot on it. Sounded like a
>piece of metal rattling. So, the salesman put some goop on it that makes
>it reflect better and it helped a little. Then he went back and put some
>green stuff around the edges and it help a little more. Overall, the CD
>sounded fairly harsh to start with and when he was done, it sounded
>noticeably better. Before this, I was a skeptic. I did not believe CD
>treatments did _any_ good whatsoever. Now I believe they help a little,
>at least for CD's that already have a problem.

I was there (ie. it was my CD). This disc is a Philips all-digital recording
of Mozart's Requiem made in West Germany. In several places, there are
distortions that (after listening to the disc on several high end systems
and speakers) Logan and I have determined is a microphone that was a bit
too close to the singers. (good ol' information overload)

Now, I'm not implying that this green stuff (in this case, it was a paint, not
a marker) is a miracle-worker that correct mistakes made during recording,
but it certainly softened the distortion alot. I believe it was a combination
of that and a good cleaning that improved the overall sound of the disc. (I
actually heard violins that sounded like they were made out of WOOD! What a
concept!)

The effect on my Dark Side of the Moon (Crapitol's 1st release, I believe)
was not as noticeable. However, if you have a high-end system (I'm talking
single components around the $300+ plus level) the "green goop" might
actually be an invesment worth making. The stuff this guy used was an opaque
green paint in a tube (supposed to coat 200 discs) that cost about $15.
That and a good cleaning should improve most discs an _audible_ amount.

>All this leads me to an interesting question: in common practice, how
>much of the data really _is_ misread off the CD? Since they are parity
>checked (I hear), has anyone made a CD player that counts and displays
>parity errors per second? It would be interesting to see how many errors
>commonly happen and would help everybody judge whether CD treatments
>are really necessary.

I'm willing to bet that the count would be high. Consider that CD ROMs and
other optical disk storage is not NEARLY a dense as the storage of data for
an audio disc. I believe that this is because the makers of the computer
CD systems have to lower the density to a _reliable_ level.

>============================================================================
>"The machine minded material man Logan Shaw
> desperately dreams of a brand new sedan. ls...@ccwf.cc.utexas.edu
> Wlll he expect long lasting gain ========================
> from a toy that will race then rust in the rain?" - elim Hall, Things Break

greg...

_ _ Disclaimer: "What I _really_ meant was..."
AMIGA! ////
//// "Run to the bedroom, in the suitcase on the left you'll find my
_ _ //// favorite axe." --Roger Waters, Pink Floyd's The Wall, One of My Turns
\\\\////
\\XX// Greg Harp gr...@ccwf.cc.utexas.edu

Pogo Joe

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Aug 5, 1990, 9:04:53 PM8/5/90
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Does someone have a sledgehammer so that I can knock Greg in the head with it?
Look, the only possible reason ffor that CD sounding any different than before
is because you cleaned it. And the only thing that may have done is prevented it
from skipping. I swear, some people are just so damned ignorant. Putting a
stupid green circle around a CD is NOT going to change the sound quality! I thought this was a joke when I fisrst saw it. My god, get a grip on reality!
You people will believe anything! You know, if you take sandpaper, and gently
wipe your discs with them, especially the poorly recorded ones, it will help smooth
the data. You'll get smoother highs, and tighter bass. Really. Try it!

Brian Boutel

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Aug 6, 1990, 12:15:10 AM8/6/90
to
In article <35...@ut-emx.UUCP>, gr...@walt.cc.utexas.edu (Greg Harp) writes:

|>
|> >All this leads me to an interesting question: in common practice, how
|> >much of the data really _is_ misread off the CD? Since they are parity
|> >checked (I hear), has anyone made a CD player that counts and displays
|> >parity errors per second? It would be interesting to see how many errors
|> >commonly happen and would help everybody judge whether CD treatments
|> >are really necessary.
|>
|> I'm willing to bet that the count would be high. Consider that CD ROMs and
|> other optical disk storage is not NEARLY a dense as the storage of data for
|> an audio disc. I believe that this is because the makers of the computer
|> CD systems have to lower the density to a _reliable_ level.
|>

My CD player, a Cambridge Audio CD2, (16 bit * 16 times oversampling)
flashes an indicator whenever it has to interpolate or mute, i.e. when
errors are detected, but can't be corrected from the redundant info on
the disk. It flashes only on disks that are visibly badly damaged, on
most disks not at all. If this is reliable, (and other samples I've seen
at my dealer's are the same,) it suggests that the sample stream being
fed into the DACs is normally correct.

--brian

Internet: br...@comp.vuw.ac.nz
Postal: Brian Boutel, Computer Science Dept, Victoria University of Wellington,
PO Box 600, Wellington, New Zealand
Phone: +64 4 721000
Fax: +64 4 712070

Francis Vaughan

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Aug 6, 1990, 2:09:36 AM8/6/90
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In article <1990Aug06.0...@comp.vuw.ac.nz>, br...@comp.vuw.ac.nz

(Brian Boutel) writes:
|> In article <35...@ut-emx.UUCP>, gr...@walt.cc.utexas.edu (Greg Harp) writes:
|>
|> |>
|> |> >All this leads me to an interesting question: in common practice, how
|> |> >much of the data really _is_ misread off the CD? Since they are parity
|> |> >checked (I hear),

Oh dear, maybe we should have a monthly posting, "Commonly misunderstood
realities about CD." CDs have a VERY high degree of error detection and error
correction. It amounts to roughly 50% redundancy, but encoded in such a way
that the sort of defect found on a CD is normally completely recoverable.
COMPLETELY.

|> |> I'm willing to bet that the count would be high. Consider that CD
ROMs and
|> |> other optical disk storage is not NEARLY a dense as the storage of
data for
|> |> an audio disc. I believe that this is because the makers of the computer
|> |> CD systems have to lower the density to a _reliable_ level.

Also not true.
A quick calculation. 80 minutes * 60 * 44KHz * 16 Bits * 2 = 850MB
Maximum data on a CD rom is 600MB. The actual data encoding method is
IDENTICAL. Some CD ROM players will also play audio CDs.

|> My CD player, a Cambridge Audio CD2, (16 bit * 16 times oversampling)
|> flashes an indicator whenever it has to interpolate or mute, i.e. when
|> errors are detected, but can't be corrected from the redundant info on
|> the disk. It flashes only on disks that are visibly badly damaged, on
|> most disks not at all. If this is reliable, (and other samples I've seen
|> at my dealer's are the same,) it suggests that the sample stream being
|> fed into the DACs is normally correct.


OK, I will second Brians comments. My cousins husband rigged up his CD
player with a counter to check on the error rates, this is his summary.


"The CD error indicator - wired from the SAA 7020 error correcting chip. C1
and C2 errors are indicated (single bit errors not indicated, > 1 error = C1,
> 2 errors = C2 - interpolation / mute). Pin 3 goes high for C1, Pin 36 for
C2. Both pins are high when a disk is not playing. Power is from pin
40 for +5v and pin 20 for 0V. Thousands of C1 errors are indicated. C2 are
thankfully very rare - only on one disk so far."

OK now, note ONE disk only with ANY C2 errors.

Now a recap from Greg Harp,

> In several places, there are
> distortions that (after listening to the disc on several high end systems
> and speakers) Logan and I have determined is a microphone that was a bit
> too close to the singers. (good ol' information overload)
> Now, I'm not implying that this green stuff (in this case, it was a
paint, not
> a marker) is a miracle-worker that correct mistakes made during recording,
> but it certainly softened the distortion alot. I believe it was a
combination
> of that and a good cleaning that improved the overall sound of the disc. (I
> actually heard violins that sounded like they were made out of WOOD! What a
> concept!)

Reality Check.

Nobody who has any understanding of the CD process can belive that the green
goop can make any difference to the number stream arriving out of the digital
chain. Is anyone still prepared to claim that scribbling on your CDs will
help aleviate recording or transcription defects? This must also apply to
cleaning the disk. Unless the disk is so filthy as to be generating
uncorrectable errors the data stream will NOT be effected.

And a final observation. CDs are played using an Infra Red laser, just
what colour a paint/goop has in the visible spectrum has to do with its
properties in the IR I don't know, and I suspect the purveyors of the goop
don't know either.

Francis Vaughan.

Eric Smith

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Aug 6, 1990, 2:58:46 AM8/6/90
to
In article <35...@ut-emx.UUCP> gr...@walt.cc.utexas.edu (Greg Harp) writes:
In article <35...@ut-emx.UUCP> ls...@walt.cc.utexas.edu (logan shaw) writes:
>All this leads me to an interesting question: in common practice, how
>much of the data really _is_ misread off the CD? Since they are parity
>checked (I hear), has anyone made a CD player that counts and displays
>parity errors per second? It would be interesting to see how many errors
>commonly happen and would help everybody judge whether CD treatments
>are really necessary.

I'm willing to bet that the count would be high. Consider that CD ROMs and
other optical disk storage is not NEARLY a dense as the storage of data for
an audio disc. I believe that this is because the makers of the computer
CD systems have to lower the density to a _reliable_ level.

CD-ROMs have only a SLIGHTLY lower data density that CD-AUDIO. For CD-AUDIO,
it is acceptable to have a small number of unrecoverable errors, because the
player can interpolate. In my experience, a disc typically has a fair number
of recoverable errors (where the error correction can recover the EXACT data
that was intended to be read), and typically 0 to 20 unrecoverable errors.
Due to the interleave process, it is extremely unlikely that two consecutive
samples are in error, so the unrecoverable errors are dealt with by
interpolation. When there is more than one consecutive sample in error,
muting takes effect.

For CD-ROM, obviously it is necessary that the error rate be much lower. By
adding one additional layer of error correction to the two layers present
in CD-AUDIO, it becomes possible to correct errors that would be
uncorrectable on an audio disk. This added layer of error correction
consumes approximately 15% of the raw capacity of the disk.
--
Eric L. Smith Opinions expressed herein do not necessarily reflect those
esm...@apple.com of my employer, friends, family, computer, or even me! :-)

Robert E. Gruber

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Aug 6, 1990, 7:46:58 AM8/6/90
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Funny, I was pretty sure this thread on CD tweaks would have
come and gone already (I just started reading this group).
Why would it hit Stereophile (a monthly magazine) long before
it hit the "electronic streets," so to speak?

Anyway, the May issue of Stereophile has an article by Robert
Harley titled: "Jitter, Errors, & Magic: Do CD rings, mats,
lotions, and unguents improve the sound from CD?" The article
attacks two general misconceptions about CD errors and sound
quality:

(1) Errors are the primary source of sonic degradation. This is
just plain wrong: most CD's have ZERO uncorrectable errors,
and even if there are one or two errors that require
interpolation (on an ENTIRE cd) this result will be momentary
and hardly noticeable. At worst, an audible tick or glitch
can result.

(2) If there are no uncorrectable errors, there can be no
difference in sound (the "bits-is-bits" argument).
The author claims that this is also wrong. As an example, he
says that while it can be proven by comparing each bit
that a digital master and a multi-generation digital copy
have identical bits, they do not sound the same. He suggests that
the most likely reason for the difference in sound is jitter,
i.e., a time-axis variation in the digital bitstream.

Let me expand on this jitter idea, since it is very
interesting. First, a footnote mentions that an article on
the effects of data jitter by Malcolm Hawksford appeared in
the Feb. 90 issue of HFN/RR. Has anyone read this article?
There was also a workshop held at the 88th AES convention on
the audible effects of data jitter. The conclusion was that
jitter in the digital data stream presented to a DAC
translates into spectral component sidebands in the resulting
audio signal. An example given in a footnote: if jitter in
the data stream presented to the DAC has a periodic nature
equivalent to 200Hz, then +/- 200Hz sidebands appear around
every spectral component in the analog music signal.

Theoretically, the bits produced by the zero-crossing
detector are buffered, and clocked out at an exact interval
to the CD player's DAC. However, the author interviewed
engineers who claimed that jitter can still reach the DAC.
In particular, engineers at a company called Madigril
reported some interesting experiments. They found that the
amount of jitter in the signal, as well as the shape and
asymmetry of the HF signal, caused changes in the resulting
audio signal (as determined by blind listening tests).
Because of these tests, they designed a CD player which
cleans up the HF signal before processing it. In addition,
the clock that clocks out words to the DAC could have jitter
itself. Apparently, a shift of as little as 100 picoseconds
can result in audible conversion-timing errors.

Jitter should have more of an effect on low-level signals,
since the error in relation to the signal will be large
compared to the same jitter applied to high-amplitude
signals. Apparently, JVC makes a "K-2 interface" that is
designed to reduce jitter. Does anyone know what this is?
The author claims that this interface seems to improve
soundstage depth and low-level resolution. Has anyone else
listened to a K-2 and experienced this?

One thing the author notes is that different pressings of the
same CD (i.e., CD's of the same music, made at different
pressing factories) have widely different amounts of jitter ---
the difference is an order of magnitude greater than the
difference in jitter produced by a cheap CD player vs. an
expensive CD transport. This implies that improvements in
the CD manufacturing process (to produce CD's with minimum
jitter) should result in significant audible improvements in
the sound (better soundstage, imaging, or whatever reduced
jitter results in) regardless of the CD player used for
playback. This is encouraging news --- assuming manufactures
will ever attempt to produce CD's with reduced jitter.

The article starts with a pretty good explanation of
how CD's are encoded and how CD players work, then goes on to
measure 6 different "CD tweaks" with respect to three things:
data error rate, ability to correct (rather than conceal)
errors, and jitter. The 6 tweaks were:

(1) CD Stoplight (a marker that applies a green paint to the
outer edge of the CD). The manufacturer claims that it
selectively absorbs the infrared laser light reflecting
around the disk interior, resulting in a better signal/noise
ratio in the HF signal recovered by the CD player's
photo-detector. Perhaps a chemist or physicist out there
could explain why (or if) the visible color of the paint
matters, since it is supposedly absorbing non-visible light.

(2) Finyl (a liquid applied to the disks surface). The
manufacture has an amazing number of claims about how the
liquid provides "optimal impedence matching" and about the
resulting sound improvements (the article reproduces
all of the claims, for a good laugh).

(3) Armor All. This tweak was "discovered" by one of
Stereophile's reviewers, who guessed that polishing the clear
surface coating which is on top of the actual data layer of
the CD might cut down on the diffraction caused by that layer
as the laser light passes through it in each direction.
Note that a Stereophile reader wrote in to say that Armor
All will rot your CD's over time, at which point the reviewer
announced that he had switched over to using Rain-X, which
he believes will not harm your CD's (no guarantees, though).

(4) CD Soundrings
(5) the Mod Squad's CD Damper disc
(6) the Arcici Laserbase, a vibration-absorbing platform

The idea behind the last three is to improve the mechanics,
i.e., to keep the CD from vibrating or wobbling as it spins
inside the player; the result of this is sopposed to be... (a
smaller amout of jitter??) (The article didn't say what the
result was supposed to be.)

By the way, the article describes error correction vs. error
concealment: An error is when a zero is read as a one, or
vice versa, or when a defect, scratch, or dust particle
causes a momentarly lapse in the data flow. Because of the
redundancy of the data encoded on the CD, a "burst error" of
up to 4000 bits can be COMPLETELY CORRECTED, i.e. the
corrected data is identical to what is missing or misread.
For larger errors, the player CONCEALS the error by making a
best guess at the correct data, using interpolation.

THE RESULTS...

First, note that NONE of the CD's tested had
uncorrectable errors, i.e., there were no errors so large
that the CD player had to do error concealment by
interpolating! There was only one CD with an error that was
one step away (one bit away?) from needing error concealment.
Upon retry, this error went away, and was probably due to a
dust spec rather than a scratch or defect in the disc.

Second, NONE of the six tweaks produced significant changes
in error rate OR jitter. (In fact, the tweaks that involved
wiping on and buffing off a solution slightly increased the
error rates, probably because the application process
introduced new scratches.) Thus, will different amounts of
jitter DO appear to have an effect on the resulting sound,
the CD tweaks did not change the sound by reducing jitter.

Now for the truly disturbing part: after preforming
experiments which seem to debunk all of the six tweaks as
being totally useless, the author goes on to say that he
could actually hear an audible difference caused by each of
these tweaks! He concludes that there is something OTHER
than jitter that affects the musicality of CD's. For the
skeptics he says "I encourage anyone who asserts dogmatically
and without a trace of doubt (a good description of my
attitude at one time) that 'bits is bits' to listen with an
open mind through a decent playback system to the effects of,
say, CD Stoplight."

I wonder what kind of "decent playback system" is required
for the differences (if they exist) to be audible?
Obviously, the better the playback system, the more it will
reveal about the sound produced at the source. Even if CD
Stoplight makes a difference, I doubt you will be able to
hear it on a boom-box with a built-in CD player; but can you
hear it on a "mid-fi" system? Since CD's themselves vary
widely in such things as amount of jitter, it seems clear
that, even if a particular CD tweak actually "works", it may
still have little or no effect on a given CD. How many CD's
do you have to try out before you decide that a given tweak
does not seem to work? Sigh! I think I will wait for the
true tweakers-at-heart to try out these things and report
their results. If you do try something and want to report it
to rec.audio, perhaps you should let us know such things as
how many different CD's you tried it on, what kind of system
you have, whether you used a blind listening test, etc.

Well, it took me a heck of a long time to write up a summary.
I hope somebody finds it interesting.

-- Bob

Disclaimer: I have no relationship with or financial interest
in Stereophile or any of the companies which produce any of
the products mentioned above. Apply any tweaks at you own risk.

------------------------------------------------------------------
Bob Gruber MIT grad student gru...@lcs.mit.edu
------------------------------------------------------------------

Timothy G. Avery

unread,
Aug 6, 1990, 10:02:44 AM8/6/90
to
In article <jamesp.649858284@bison> jam...@wacsvax.uwa.oz (James Pinakis) writes:
>I've heard from a somewhat unreliable source that if one colours the outside
>and inside edges of a CD with green (and I'm told it _has_ to be green
>or else it won't work) permanant felt pen, the CD will "sound better"
>and skip less. It's meant to have something to do with eliminating/reducing
>reflected light.

Its a myth. I read an entire article this past year sometime in the
Columbus Dispatch which claimed the same thing... except they said the color
had to be turquoise. It also said there weren't any real measureable
improvements, but many people claimed it sounded better.

Well, any improvements in sound was purely psychological. Digitally
reproduced sound will be unaffected by the amount of light it receives or
reflects. All the light does is to read the data off of the disc. It either
does this with complete success or no success (a "skip"), and the amount
of light it loses or gains does not effect the general performance of the
disc. A successful retrieval of data will be then be digitally processed
by the micro-processor chips inside the CD player, which have nothing to
do with the laser light, but has everything to do with the actual sound you
hear.

So, before you or anyone you knows goes around coloring the edges of all of
your disks green (or turquoise or red or plaid...), save yourself a lot
of bother for no reason.

ch...@umiami.miami.edu

unread,
Aug 6, 1990, 11:45:40 AM8/6/90
to
In article <jamesp.649858284@bison>, jam...@wacsvax.uwa.oz (James Pinakis)
writes:

> I've heard from a somewhat unreliable source that if one colours the outside
> and inside edges of a CD with green (and I'm told it _has_ to be green
> or else it won't work) permanant felt pen, the CD will "sound better"
> and skip less. It's meant to have something to do with eliminating/reducing
> reflected light. Has anyone else heard this, and if so is it from somewhere
> more reliable than "the guy at the local hi-fi shop"? Has anyone tried it?
> I tried it on some CDs that my ageing CD player jumps around on and managed
> to convince myself that my CD player was able to find the start of tracks
> more easily, but still jumped occasionally. But as for "sounding better"...
>
> james
> jam...@bison.cs.uwa.oz.au

Here's my attempt to put this farce to rest. (My $0.02)

One of my professor's here, Ken Pohlmann (perhaps some of you have read his
books on CD's and Digital Audio?) heard about this and decided to do a little
test in our studio here (I wasn't at the test, so the details of the actual
test may be a bit different than what I write here, but this should get the
idea across). He took some CD players (I believe a portable, a Denon, and one
other machine), an amp, some speakers, and a handful of CD's. The CD's he
chose were checked to be sure they had the same lot number (it would be
possible for a difference in quality if they were from different pressings)
and listened to without the green ink. Then, coloring one of each CD with
green ink, repeated the test. In other words, all the discs were listened to
without the green ink, and compared with a double of itself, and then the
green ink was applied to one of the pairs. Well, we had a variety of people
in the studio that day, some skeptical, some not, all listening to the test.
_No one_ heard even the slightest difference in the sound, and no one knew
whether they were listening to a disc with or without the green ink. There
were no differences in the amount of errors displayed, either.

Disclaimer: I do not speak for Ken in any way, shape or form. I am merely
telling you what I know about a pretty legitimate test that he performed for
the students of his digital audio class (which I took last semester). And, if
you know what's going on inside a CD player and how the whole Digital Audio
scheme works, you'll know without a test that this green ink thing could never
make any CD sound better! The power of suggestion can be great!
--
Chuck Urwiler University of Miami Music Engineering Voice & Keys
===========================================================================
chuck@umiami -or @umiamivm (Bitnet) | "Sometimes the one thing that you're
ch...@umiami.miami.edu (Internet) | looking for, is the last thing on
ch...@miavax.ir.miami.edu (Internet) | your mind" -Robbie Nevil
===========================================================================
Disclaimer: I only work and learn at this University. I don't speak for it!

Dr Thrasher

unread,
Aug 6, 1990, 12:09:58 PM8/6/90
to
Bascially all you are doing by coloring the CD green (IF it does anything
at all, which I am still not convinced) is reverting back to the stone-age
of vinyl record quality. Since CD's are digital, they are strictly the absolute
best imaging that you can get. And coloring them green would if anything
cut down on the frequency range that the CD can offer. Why else does coloring
it reduce that "metallic" noise on that on CD? It is because by coloring
it you are just reducing ALL of the musical quality.

For crying out loud! Just adding some green ink cant magically make
the CD sound better at some places, and leave all of the rest of it as-is.
Rather, it just dulls the entire recording, giving you just total crap.

Scott Bulmahn
sbul...@yoyodyne.ncsa.uiuc.edu

--

Mika R Iisakkila

unread,
Aug 6, 1990, 2:26:35 PM8/6/90
to
a...@deimos.caltech.edu (Alain Picard) writes:

> In article <35...@ut-emx.UUCP>, ls...@walt.cc.utexas.edu (logan shaw) writes...

> >All this leads me to an interesting question: in common practice, how
> >much of the data really _is_ misread off the CD?

> WHAT DIFFERENCE does it make how many errors are picked up by the


> error checking circuit? That's precisely what it's there for!
> You can make a mistake on every single bit, if you correct it,
> you still have the same information. Not ONE BIT less.

Yeah, it DOES make a slight difference. Let's say that I have
a CD player that can detect and correct 100 erraneous bits per second.
Then, there comes this 101st error bit and my player jumps. If it's
possible to get rid of that 101st bit and play the record without any
audible errors, I want to do it, whether it involves coloring my CD's
green or placing a bowl of camel shit on top of the left speaker. It
would be very interesting to see the error rate coming off of the
disk, so you could tell for _sure_ if these witchcraft techiniques are
of any help.

Before you press the F key, read this article again - I'm not
telling you to color your CD's.
--
Treasury counter-intelligence Kennedy Cocaine Uzi [Hello to all my
fans in domestic surveillance] strategic NSA domestic disruption
smuggle CIA $400 million in gold bullion cryptographic supercomputer
El Salvador Mossad DES Ft. Bragg Marxist Nazi genetic Nancy Reagan

William Spencer

unread,
Aug 6, 1990, 7:12:24 PM8/6/90
to
in article <1990Aug6.0...@ux1.cso.uiuc.edu>, ja2...@uxa.cso.uiuc.edu (Pogo Joe) says:
>
> Does someone have a sledgehammer so that I can knock Greg in the head with it?

This is the calm, mature reply expected from the net.experts. I got
somethin' to say, but not without a bit more history.


Pogo Joe also said:
> If that isn't the biggest bunch of crap I have heard since the "CD Soundrings"
> Jeez! What are these "audiophiles" smoking? They are the most unscientific
> religious group of bozos I can think of.

Craig Demel is even less diplomatic:
>
> hahahahahahahahahahahahahahahahahahahahahahahahhaahahahahahahahahahahahahahaha
> hahahaahhaahahahahaahahahahahahahahahahahahaHAHAHAHAAHAHAHAHAHAHAHAHAHAHAHAHAHAHA
> HAHAHAHAHAHAHAHAAHAHAHAHAHAHAHAHAHAHAHAHHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAAH
> AHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA
[wide bandwidth alpha graphics deleted]

in article <12...@sirius.ucs.adelaide.edu.au>, fra...@cs.ua.oz.au (Francis Vaughan) says:

> Reality Check.
>
> Nobody who has any understanding of the CD process can belive that the green
> goop can make any difference to the number stream arriving out of the digital
> chain.
>

>Is anyone still prepared to claim [....]

Indeed. Who is truly ready for a real net.lynching?

in article <jamesp.649858284@bison>, jam...@wacsvax.uwa.oz (James Pinakis) says:
>
> [I'm not sure whether I should have cross-posted this to one of the urban
> myth newsgroups. Maybe someone can tell me if it's all crap. ]
>

> I've heard from a somewhat unreliable source that if one colours the outside
> and inside edges of a CD with green (and I'm told it _has_ to be green
> or else it won't work) permanant felt pen, the CD will "sound better"
> and skip less. It's meant to have something to do with eliminating/reducing
> reflected light. Has anyone else heard this, and if so is it from somewhere
> more reliable than "the guy at the local hi-fi shop"? Has anyone tried it?
> I tried it on some CDs that my ageing CD player jumps around on and managed
> to convince myself that my CD player was able to find the start of tracks
> more easily, but still jumped occasionally. But as for "sounding better"...

Unlike the net.experts previously quoted James actually tried it!!!!!
Instead of spouting theory he used his ears! I'm suprised he didn't
get flamed for such of an "unscientific" approach!
He didn't hear a difference and that's okay.
Of course he didn't ASK for theory either, he asked if anyone had tried
it, but that didn't stop a net.rumble.

And now for the truly bold....

in article <35...@ut-emx.UUCP>, ls...@walt.cc.utexas.edu (logan shaw) says:
>
> We were listening to a CD which had a nasty spot on it. Sounded like a
> piece of metal rattling. So, the salesman put some goop on it that makes
> it reflect better and it helped a little. Then he went back and put some
> green stuff around the edges and it help a little more. Overall, the CD
> sounded fairly harsh to start with and when he was done, it sounded
> noticeably better. Before this, I was a skeptic. I did not believe CD
> treatments did _any_ good whatsoever. Now I believe they help a little,
> at least for CD's that already have a problem.

and:


in article <35...@ut-emx.UUCP>, gr...@walt.cc.utexas.edu (Greg Harp) says:
>
> I was there (ie. it was my CD).

[...]


> Now, I'm not implying that this green stuff (in this case, it was a paint, not
> a marker) is a miracle-worker that correct mistakes made during recording,
> but it certainly softened the distortion alot. I believe it was a combination
> of that and a good cleaning that improved the overall sound of the disc. (I
> actually heard violins that sounded like they were made out of WOOD! What a
> concept!)

>[...] if you have a high-end system (I'm talking


> single components around the $300+ plus level) the "green goop" might
> actually be an invesment worth making.

I presume that Pogo Joe hasn't caught up with these two with his
sledgehammer :-).

My turn:

Has anyone played around with the
synthesizer on a Commodore 64? The thing's noisy as hell. One thing
that's interesting is that the noise changes when the program activity
changes. For example, set up the synth chip for a constant tone and return to
the prompt. Then run a busy BASIC program. Hear the noise increase? At
first thought this makes no sense because everything in the computer
occurs at a high frequency far out of the range of hearing. However,
patterns of noise can contain subharmonics which bleed through. This could
explain how digital signals can bleed through to the audio sections.
Only if the high frequency digits produce no subharmonics will there
be absolutely no bleedthrough in any practical system. This includes
external digital processors.

in article <12...@sirius.ucs.adelaide.edu.au>, fra...@cs.ua.oz.au (Francis Vaughan) says:
> My cousins husband rigged up his CD
> player with a counter to check on the error rates, this is his summary.

>[...]


> Thousands of C1 errors are indicated.

Although errors are are only one source of digital crosstalk, if it's a
signifigant one this is certainly enough errors.


One anecdotal claim is that audible effects are related to the acoustical
effect of the treatment on the CD plastic. Sort of as if there is some
mechanism that picks up this. Errors might explain this. Vibration
would cause surges of errors at the vibration frequency. As I was
explaining before, it's not enough that errors or other digital signals occur,
they must have a signal content or pattern in the audible range.

Enough of my theories. Do I hear a difference? Well, I haven't heard
all the treatments on the best systems. My first experiments with
Armor All were pretty noneventful. However, as I previously reported,
an event occured that eliminated my skepticism:

>The tweak is: Goldmund Cones
>
>Program for the demo was Ladysmith Black Mambazo -- all male voices.
>
>First, without: Noticable breath-like noises. At least that's what I would
>tend to dismiss them as.
>With cones these sounds dissappeared. Remaining were real breath noises,
>far more subtle and natural. Other sounds were unaffected. The Goldmund
>rep switched them back and forth
>a few times. "Sounds like there's dust on the needle without them," I said.
>.
>This was on a system with Euphonic's player & a Wadia decoder, Thresholds,
>and Mirage M1's.
>Then we tried the Onkyo CD changer and amp and Mirage mini monitors. Same
>thing, though not as noticable with the less impressive speakers.
>
>According to the Goldmund rep, the cones act as mechanical diodes. Vibration
>goes out and doesn't come in.
>material inside. According to the rep, lesser spikes such as Tiptoes can
>actually make matters worse by reflecting vibration back into the player.
>
>Don't ask me why vibration's audible. It just is.

>The cones are a set (3) for $195. Ugh. Any machinists out there?

Check it out. As for me, my flame proof jacket is on.

greenpeace,
bill S.

Ryan Miller

unread,
Aug 6, 1990, 7:24:44 PM8/6/90
to
>From: jam...@wacsvax.uwa.oz (James Pinakis)
>Message-ID: <jamesp.649858284@bison>

>
>I've heard from a somewhat unreliable source that if one colours the outside
>and inside edges of a CD with green (and I'm told it _has_ to be green
>or else it won't work) permanant felt pen, the CD will "sound better"
>and skip less. It's meant to have something to do with eliminating/reducing
>reflected light. . . .
>
>james
>jam...@bison.cs.uwa.oz.au

This issue came up some time ago, I do not remember exactly when it was.
At that time, I asked one of our optical experts working on CD ROM and
related technology about it. I don't remember his exact words, but he
said something to the effect that `he couldn't see how it would make
any difference one way or the other.'

The way I see it, if you think some CD sounds or tracks better because
there is green marker pen on it then put green marker pen on it. Our
bodies can do amazing things when our minds believe in something.
---
Ryan Miller
ry...@hpfcla.HP.COM
---
The material presented does not necessarily reflect the
opinion, or position of my employer, or anyone else.

Chaz Larson

unread,
Aug 6, 1990, 7:25:19 PM8/6/90
to
In article <16...@abvax.UUCP> t...@odin.icd.ab.com (Timothy G. Avery) writes:
>So, before you or anyone you knows goes around coloring the edges of all of
>your disks green (or turquoise or red or plaid...), save yourself a lot
>of bother for no reason.

Wait! I've just thought of a test for this green marker hoo-ha I'll perform
tonight! I'll take a cd and paint half of the circumference green; this should
result in a wowing effect as the green-paint-improvements drop in and out and
in and out...

yeah, that's it!

Actually, I recall reading in Scientific American around the time of the initial
introduction of CD's that the data redundancy was such that one could drill a
hole of something like 2mm diameter through the disc and never hear it. Does
anyone know the real number or have the reference? I now have a CD I am willing
to drill a hole through for testing purposes... 8)

<chaz>


--
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
"Must think...bubble pipe will relax me and I think..."
- Flaming Carrot
cla...@ux.acs.umn.edu AOL:Crowbone

David Tholen

unread,
Aug 6, 1990, 9:25:36 PM8/6/90
to
In article <1990Aug6.1...@mintaka.lcs.mit.edu>, gru...@athena.mit.edu (Robert E. Gruber) writes:

> Now for the truly disturbing part: after preforming
> experiments which seem to debunk all of the six tweaks as
> being totally useless, the author goes on to say that he
> could actually hear an audible difference caused by each of
> these tweaks!

Here's a case study in logic. I color my CD edges green; I hear an audible
difference; therefore, the green edge had an effect. NOT NECESSARILY TRUE.
As other postings in this newsgroup have discussed, audio components change
their "sound" as they warm up (that's why some audiophiles leave their
equipment on all the time). Therefore, the audible difference between the
regular CD and the green-edged CD can't be attributed to the green edge unless
you can rule out the possibility that one of the other components in the
audio chain changed it's sound during the course of the test. An audible
difference is a necessary, but not sufficient, condition for proving that
green edges have an effect. Repeatability would certainly help prove the
point, but I have yet to see anybody demonstrate repeatability.

Now you know why universities require science courses for graduation. They
want to develop students' analytical skills. If we had a more critically
thinking public, a lot of these scams wouldn't have a chance to rip off
the consumer.

Ti Kan

unread,
Aug 6, 1990, 10:39:13 PM8/6/90
to
Oh boy, here we go again... along with the sound rings and the armor-all.
Did you know that someone has commercialized this concept and you can
now find "CD-edge marker pens" marketed through some hi-fi and record
stores! It never ceases to amaze me how quickly someone will jump at
the opportunity to make a few bucks (despite the absurdities of the
product).

-Ti
--
Ti Kan \\\
vorsprung durch technik! \\\
Internet: t...@altos.com /// \\\
UUCP: ...!{sun|sco|pyramid|amdahl|uunet}!altos!ti ////////\

Chaz Larson

unread,
Aug 6, 1990, 7:14:12 PM8/6/90
to
In article <35...@ut-emx.UUCP> gr...@walt.cc.utexas.edu (Greg Harp) writes:
>
>Now, I'm not implying that this green stuff (in this case, it was a paint, not
>a marker) is a miracle-worker that correct mistakes made during recording,
>but it certainly softened the distortion alot. I believe it was a combination
^^^^^^^^^^^^^^^^^^^^

>of that and a good cleaning that improved the overall sound of the disc. (I
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

>
>That and a good cleaning should improve most discs an _audible_ amount.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

I offer for sale a green paint marker for the low price of $15. Coating the
edges of your car's rocker covers, in conjunction with a good tune-up, will
improve your engine's performance remarkably.

This is the second go-round [that I've seen] on rec.audio for the green goop
theory. Does this mean we can expect another wave of "Armor All makes my
CD's sound 5000% better!!!!!" posts in the near future?

young.u.huh

unread,
Aug 6, 1990, 4:10:58 PM8/6/90
to

Perhaps someone could do a statistical study on this "phonomena."
The results may be interesting.
EXAMPLE:

1. Get a sample of listeners (audiophiles, if you prefer).

2. Get a sample of CDs in pairs, i.e., two of each title.

3. Color some of the CDs so that each of the following
pair-combinations are represented:

(colored, colored)
(colored, not colored)
(not colored, not colored)

4. Have each listener to listen to the pairs of CDs, switching
back and forth between the two, without knowing which CDs are
colored, of course! Ask the listener to identify which one
sounds "better" or whether they sound "indistinguishable."

5. Collect and analyze the data (use tests of significance, etc.).

Eric Smith

unread,
Aug 7, 1990, 12:38:35 AM8/7/90
to
In article <1990Aug6.1...@mintaka.lcs.mit.edu> gru...@athena.mit.edu (Robert E. Gruber) writes:

Anyway, the May issue of Stereophile has an article by Robert
Harley titled: "Jitter, Errors, & Magic: Do CD rings, mats,
lotions, and unguents improve the sound from CD?" The article
attacks two general misconceptions about CD errors and sound
quality:

(1) Errors are the primary source of sonic degradation. This is
just plain wrong: most CD's have ZERO uncorrectable errors,
and even if there are one or two errors that require
interpolation (on an ENTIRE cd) this result will be momentary
and hardly noticeable. At worst, an audible tick or glitch
can result.

(2) If there are no uncorrectable errors, there can be no
difference in sound (the "bits-is-bits" argument).
The author claims that this is also wrong. As an example, he
says that while it can be proven by comparing each bit
that a digital master and a multi-generation digital copy
have identical bits, they do not sound the same. He suggests that
the most likely reason for the difference in sound is jitter,
i.e., a time-axis variation in the digital bitstream.

The jitter on playback doesn't make it into the digital copy. If you
could somehow make multiple analog copies of a digital tape, then
try to play it back, the analog copying process could well have
destroyed your data. That's not how digital recorders work. They
copy the bits, not the jitter. They may have as much or more jitter
on playback as a CD player, but it isn't cumulative with dubbing.

Most if not all digital recorders buffer the data both on record and
playback to avoid dependence on tape (or disk) speed, just as a CD
player does on playback. The fullness of the buffer provides the
feedback for the speed control system.

Beats me how the same people who can't sense any problem with speed
control on phonograph turntables can hear a difference due to
jitter of a digital audio signal. The relative error is several
orders of magnitude lower. But then, that must be the problem.
Maybe increasing the jitter would add "warmth". :-)

...

Theoretically, the bits produced by the zero-crossing
detector are buffered, and clocked out at an exact interval
to the CD player's DAC.

The "exact interval" is a quartz crystal oscillator. Not the
most accurate frequency source on earth, but how many people
buy Cesium frequency reference locked turntables? :-)

You could perhaps replace the crystal in you CD player with one
of the crystal oven types (temperature controlled). I'd spend my
money elsewhere, as once my CD player warms up, it's temperature
stays fairly constant.

I haven't yet heard anyone complain about a CD player sounding
different as it warms up; perhaps this will be the next big
golden-ears controversy. :-)

...

Jitter should have more of an effect on low-level signals,
since the error in relation to the signal will be large
compared to the same jitter applied to high-amplitude
signals. Apparently, JVC makes a "K-2 interface" that is
designed to reduce jitter. Does anyone know what this is?
The author claims that this interface seems to improve
soundstage depth and low-level resolution. Has anyone else
listened to a K-2 and experienced this?

I haven't listened to a K-2 machine, but I believe it works
similarly to the Sony CDP-R1.

The SPDIF digital audio interface (the consumer version of AES/EBU,
used by most consumer players), is self clocking. The signal is
bi-phase mark encoded, and a clock recovery circuit (basically a
PLL) is used at the receiving side of the link. If there was a
vast amount of jitter in the transmitted signal (unlikely), the
clock recovery could fail. The clock recovery circuit itself may
introduce some jitter, which when coupled with the source jitter
may introduce error in a D/A converter. As described above, this
jitter will not affect the data when a digital dub is made.

The CDP-R1 (and probably the K2) use a separate clock signal to
avoid the need for clock recovery. The only way this could
reduce jitter is if the clock source on the transmit side of
the link has less jitter than the clock recovery circuit in an
SP-DIF link adds.

If you don't like the idea of clock recovery from a data stream,
consider that your computer uses essentially the same process
every time it reads a disk sector. Is it reliable?

To me, this seems like a .00001% gain for 10X dollars.

...

One thing the author notes is that different pressings of the
same CD (i.e., CD's of the same music, made at different
pressing factories) have widely different amounts of jitter ---
the difference is an order of magnitude greater than the
difference in jitter produced by a cheap CD player vs. an
expensive CD transport. This implies that improvements in
the CD manufacturing process (to produce CD's with minimum
jitter) should result in significant audible improvements in
the sound (better soundstage, imaging, or whatever reduced
jitter results in) regardless of the CD player used for
playback. This is encouraging news --- assuming manufactures
will ever attempt to produce CD's with reduced jitter.

Any reasonable amount of jitter in the data rate of the bit stream on the
disk will have no effect whatsoever on the audio, since the data is
buffered. A large enough amount of jitter on the disk may cause data
errors, which will be corrected, or (less likely) interpolated or
concealed.

...

Now for the truly disturbing part: after preforming
experiments which seem to debunk all of the six tweaks as
being totally useless, the author goes on to say that he
could actually hear an audible difference caused by each of
these tweaks! He concludes that there is something OTHER
than jitter that affects the musicality of CD's. For the
skeptics he says "I encourage anyone who asserts dogmatically
and without a trace of doubt (a good description of my
attitude at one time) that 'bits is bits' to listen with an
open mind through a decent playback system to the effects of,
say, CD Stoplight."

Can you say placebo? I knew you could. :-)

...

Well, it took me a heck of a long time to write up a summary.
I hope somebody finds it interesting.

Yes, thanks for posting it!

Before everybody flames me, I should point out that I am criticizing
the article that was summarized, not Robert.

Mike Harrison

unread,
Aug 6, 1990, 8:03:11 PM8/6/90
to
In article <1990Aug6.0...@ux1.cso.uiuc.edu> ja2...@uxa.cso.uiuc.edu (Pogo Joe) writes:
>from skipping. I swear, some people are just so damned ignorant. Putting a
>stupid green circle around a CD is NOT going to change the sound quality! I thought this was a joke when I fisrst saw it. My god, get a grip on reality!

You're absolutely right! What hogwash, coloring CDs green!
No, you see, what you *really* do to improve the sound quality is
1) Make a pentagram on the floor (preferably in the direct centre of
the room)
2) Gently (gently, now!) place the CD, data side up, in the very center
of the pentagram.
3) Consecrate some holy water, and spread it evenly on the disc. It's
real important to get this part exactly right, so be careful!
4) Turn the lights down low, burn some incense (preferably some pine
treeish smelling stuff), assume a cross-legged position, and
pray to the god Apollo for precisely 22.34 minutes.


It's amazing how good this method works!! I've found my CDs sound 10 times
better!!!!

Mike
--
Mike Harrison | "We sell our souls, we sell our souls for big
mrhar...@lion.uwaterloo.ca | wedge; Are we selling out tomorrow for today?"
mrhar...@tiger.uwaterloo.ca| -- Fish

Steve Kanefsky

unread,
Aug 6, 1990, 10:11:03 PM8/6/90
to
In article <19...@ux.acs.umn.edu> cla...@ux.acs.umn.edu (Chaz Larson) writes:
>
>Actually, I recall reading in Scientific American around the time of the initial
>introduction of CD's that the data redundancy was such that one could drill a
>hole of something like 2mm diameter through the disc and never hear it. Does
>anyone know the real number or have the reference? I now have a CD I am willing
>to drill a hole through for testing purposes... 8)

Yes, a good player can handle a single dropout of 2mm, and double dropouts
almost that large. No need to drill holes in your CDs, there is a standard
test disc with varying-size dropouts (Verany disc of calibrated dropouts.
Perhaps others as well).

However, it is obvious you have responded without reading all the relevant
information. The "bits-is-bits" article is somewhat naive. Blind listening
tests have indicated differences in identical bitstreams due to jitter
(timebase errors in the bitstream) and ripple (deviation from perfect
square waves in the digital signal). No one claims that green marker
reduces errors in the bitstream. What *is* strange is that it doesn't
reduce jitter or ripple either. But it's clear that we don't understand
all the factors which can influence the final analog output of a CD
player, so don't be so skeptical unless you've listened to the difference.

On the other hand, I'm not willing to accept casual listening tests as
evidence, and its much more difficult to construct good listening
tests than one would imagine. Rapid A/B switching can ruin a test,
and listening fatigue sets in quickly. In the Summer/Fall issue
of Audio Ideas Guide, a blind listening test of different speaker
and interconnect cables was performed. Subjects were asked whether
cable A sounded the same as, slightly different, or very different than
cable B, or whether they couldn't tell. Overall, subjects were only
right 51% of the time. However, each subject went through several
trials, and subjects were right 100% of the time on their first trial,
thus indicating that there is a small difference, but listening
fatigue sets in quickly. There were only 7 subjects, but that still
gives odds of only 1 in 128 that they would all be correct if they
couldn't hear a difference. (BTW, this test was comparing $0.10/foot
18-gauge zip-cord to the most expensive, $32/foot Monster Cable).


--
Steve Kanefsky
kane...@cs.umn.edu

Lance R. Bailey

unread,
Aug 7, 1990, 2:37:34 AM8/7/90
to
In article <1990Aug6.1...@mintaka.lcs.mit.edu>, gru...@athena.mit.edu (Robert E. Gruber) writes...

first of all, THANK YOU for taking the time, to summarize the article.

>
> ... the author goes on to say that he


>could actually hear an audible difference caused by each of
>these tweaks! He concludes that there is something OTHER

>than jitter that affects the musicality of CD's. ...

hmmmmmm, sounds like a typical case of "my measurements do not
back up what i experience, therefore my measurements are wrong.

this is a great example of what a lot of people cannot grasp. The human ear is
an infinitely complex piece of machinery. The listening process involves not
only the ear (again, a basically mechanical device) but your mind and it's
interpretation of the signal passed to it. Thus, there is a host of
psychological effects/affects which control the listening experience.
Attempting to measure a piece of musical equipment with electro-mechanical
devices and parrallel what the experienced listener effects is a difficult
task at best, impossible on average.

_________________________________
Lance R. Bailey, Systems Manager | Robarts Research Institute
email: l...@rri.uwo.ca | Clinical Trials Resources Group
vox: 519-663-3787 ext. 4108 | P.O. Box 5015, 100 Perth Dr.
fax: 519-663-3789 | London, Canada N6A 5K8

Eric Smith

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Aug 7, 1990, 5:39:26 PM8/7/90
to
In article <7...@ria.ccs.uwo.ca> l...@rrivax.rri.uwo.ca (Lance R. Bailey) writes:

this is a great example of what a lot of people cannot grasp. The human ear is
an infinitely complex piece of machinery.

You're right... I can't grasp an infinitely complex piece of machinery.
I believe the human ear is of finite complexity, and that certain aspects
of its behavior are fairly well understood. I'll grant that we clearly
don't understand it completely.

The listening process involves not
only the ear (again, a basically mechanical device) but your mind and it's
interpretation of the signal passed to it. Thus, there is a host of
psychological effects/affects which control the listening experience.
Attempting to measure a piece of musical equipment with electro-mechanical
devices and parrallel what the experienced listener effects is a difficult
task at best, impossible on average.

If we can assume for that what a human hears is a function of the audio
signal arriving at his or her ears, then we should be able to determine
whether two audio signals will be percieved the same by measuring the
signals with a transducer that has the same response as the ear. What
happens after the ear (i.e., in the brain) is then irrelevant unless it
depends on factors other than the audio. Since we are discussing the
effects of changes in the audio signal path,

We probably can't make transducers with the same response as the human
ear, but if we have two audio signal paths (A and B) to compare, and can
determine that A presents a more accurate version of the source signal to
the ear than B, we can conclude that the perception of A will be closer
to the perception of the source than B will.

Note that this says nothing about which sounds "better".

Eric Smith

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Aug 7, 1990, 5:40:39 PM8/7/90
to
In article <26be2527-84....@tronsbox.xei.com> akcs.re...@tronsbox.xei.com (alan berger) writes:

Green markers: if the cd manufacturers haven't figured it out by now, don't
you think that they would have started to include special greenie markers
with every overpriced disk that you purchase?
Seems there's a market for everything these days.

Of course they wouldn't include them with the disk. They would want to
make more money by selling them, not less by giving them away.

Evan Whitney

unread,
Aug 6, 1990, 7:45:45 PM8/6/90
to
>WHAT DIFFERENCE does it make how many errors are picked up by the
>error checking circuit? That's precisely what it's there for!
>You can make a mistake on every single bit, if you correct it,
>you still have the same information. Not ONE BIT less.

Wrong. The difference is in the power supply. On my CD player (Magnavox 650)
when the correction circuit kicks in, there is a slight drain on the
power supply that produces an audible noise in and of itself, let alone
its effect on the intended audio portion. For most CDs this is not a
problem and goes unnoticed. However, when a particularly marginal CD is
played, the CD player produces a very annoying high-pitched whine that can be
heard in the next room. (Check out Nu Shooz's _Told You So_ CD for an excellent
example of this phenomemenon.)

The player appears to be able to play the CD, but must be making hundreds
(thousands?) of corrections per second. It was so bad, I couldn't bear to
listen to the whole thing, no matter how loud I turned it up.

The fewer the corrections, the better, as far as I'm concerned.

Evan

Alan Waterman

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Aug 7, 1990, 5:51:44 PM8/7/90
to

Unbelievable!!!!!!!!!!!!!!!!!!!!!! The original posting about coloring
CD edges green came many months ago. The person who posted it meant
it as a joke and couldn't believe that people were actually believing it,
so to clear the record he clarified this point about a month later.

Now the debate has started all over again because of the people who obviously
did not see the posting that said this was all a practical joke.

Dana A. Bunner

unread,
Aug 7, 1990, 10:37:45 AM8/7/90
to
In article <26be2527-84....@tronsbox.xei.com>, akcs.re...@tronsbox.xei.com (alan berger) writes...

>depending of course upon the sampling of the system, does it really matter?

>
>Green markers: if the cd manufacturers haven't figured it out by now, don't
>you think that they would have started to include special greenie markers
>with every overpriced disk that you purchase?
>Seems there's a market for everything these days.

Or better yet, we should soon begin to see the Audiophile labels like
Chesky, etc., sellings CD's "Pre-greened". Yes buy our CD's with the
pure green edges. No! Buy ours, our extensive research shows that one
needs a little extra blue in the tint, as well as a touch of red to
achieve the perfect tint to block laser refractions!

And if the lasers used are not all using the same light wavelight, we may
need special markers customized for JVC, SONY, and Pioneers as opposed
to domestic CD players.

If used correctly, there is a lot of money to be made.

Now for the next topic...has anyone ever tried the "Golden Ears" leather
ear-surrounds? By the time one has tested 200 interconnects, 420 speaker
stands, 59 power cords, ..., etc., etc. it would seem that someone out
there has tested the "EARS". Come on now, fess up and give us a report!

Dana B.

alan berger

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Aug 7, 1990, 2:02:10 AM8/7/90
to

Jim Roth

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Aug 7, 1990, 11:01:20 PM8/7/90
to

In article <1990Aug6.1...@mintaka.lcs.mit.edu>, gru...@athena.mit.edu (Robert E. Gruber) writes...

>Anyway, the May issue of Stereophile has an article by Robert


>Harley titled: "Jitter, Errors, & Magic: Do CD rings, mats,
>lotions, and unguents improve the sound from CD?" The article
>attacks two general misconceptions about CD errors and sound
>quality:
>
> (1) Errors are the primary source of sonic degradation. This is
> just plain wrong: most CD's have ZERO uncorrectable errors,
> and even if there are one or two errors that require
> interpolation (on an ENTIRE cd) this result will be momentary
> and hardly noticeable. At worst, an audible tick or glitch
> can result.
>
> (2) If there are no uncorrectable errors, there can be no
> difference in sound (the "bits-is-bits" argument).
> The author claims that this is also wrong. As an example, he
> says that while it can be proven by comparing each bit
> that a digital master and a multi-generation digital copy
> have identical bits, they do not sound the same. He suggests that
> the most likely reason for the difference in sound is jitter,
> i.e., a time-axis variation in the digital bitstream.

Well, this "jitter" thing seems to be the latest discovery of the analog
people.

In fact, the phenomena is very well understood, even classically so
as far as the digital signal processing literature goes. See for example
the nearly 30 year old paper:

"On the problem of time jitter in sampling" by A. V. Balakrishnan,
IRE Transactions on Information Theory, April 1962 pp 226-236.

Clock jitter on playback is a form of low index phase modulation and
that is all. If it were really the dire problem that these analog
people make it out to be, then one would readily be able to hear
the residual noise sidebands when notching out a pure sinewave from
a test CD (using nothing more than a low-technology twin-tee notch
filter.)

Well, I have tried this with a number of players over the years
(actually I was looking for quantization noise in general, but this
will reveal jitter effects too.) There was no descernablle modulation
of the sinewave signals, regardless of the frequency, caused by shaking
the player or even mounting CD sound rings. The dominant spectral
contamination was ordinary quantization noise, harmonic distortion
products, and beats with the sampling clock (at very high frequencies.)

Some players like the Denon 1520 were exceptionally pure in their
response, while others had quite noticible forms of distortion after
the notch filter.

As far as I'm concerned, this is yet another attempt by these magazine
writers to generate useless controversy by blowing up a trivial effect
and getting people anxious about their equipment.

>Let me expand on this jitter idea, since it is very
>interesting. First, a footnote mentions that an article on
>the effects of data jitter by Malcolm Hawksford appeared in
>the Feb. 90 issue of HFN/RR. Has anyone read this article?

Hawksford has written some questionable things (as well as some
interesting stuff.) His paper on "fuzzy distortion" (not related
to digital audio) was a bit off the deep end.

>There was also a workshop held at the 88th AES convention on
>the audible effects of data jitter. The conclusion was that
>jitter in the digital data stream presented to a DAC
>translates into spectral component sidebands in the resulting
>audio signal. An example given in a footnote: if jitter in
>the data stream presented to the DAC has a periodic nature
>equivalent to 200Hz, then +/- 200Hz sidebands appear around
>every spectral component in the analog music signal.

Yes, spectral sidebands are produced, but just how "severe" is
this effect in practice?

And do you really expect me to believe that the data on a typical
CD is so pure that one can actually hear the profound effects that
are claimed by merely tweaking ones *player*?

>In particular, engineers at a company called Madigril
>reported some interesting experiments. They found that the
>amount of jitter in the signal, as well as the shape and
>asymmetry of the HF signal, caused changes in the resulting
>audio signal (as determined by blind listening tests).
>Because of these tests, they designed a CD player which
>cleans up the HF signal before processing it. In addition,
>the clock that clocks out words to the DAC could have jitter
>itself. Apparently, a shift of as little as 100 picoseconds
>can result in audible conversion-timing errors.

People selling products are always making claims.

>Jitter should have more of an effect on low-level signals,
>since the error in relation to the signal will be large
>compared to the same jitter applied to high-amplitude
>signals. Apparently, JVC makes a "K-2 interface" that is
>designed to reduce jitter. Does anyone know what this is?
>The author claims that this interface seems to improve
>soundstage depth and low-level resolution. Has anyone else
>listened to a K-2 and experienced this?

Clock jitter does not necessarily have more or less effect on
low level signals. I heard no jitter effects in notching out a
fade to silence sinewave on players.

Clock jitter does have a greater effect on high frequency signals,
however my observations were that classical nonlinearity giving
rise to beats with the clock and quantization noise floor
predominated by far, even for very good players.

But let's be real, shall we? Try looking at the modulation noise
sidebands on analog media like the LP or tape. Of course this is
magically "inaudible" to the analog luddites writing for the
Stereofool. Even though it is *orders of magnitude* worse than
what happens with digital audio.

> [... none of the "tweeks" effect clock jitter or bit error rates ...]

>Now for the truly disturbing part: after preforming
>experiments which seem to debunk all of the six tweaks as

>being totally useless, the author goes on to say that he


>could actually hear an audible difference caused by each of
>these tweaks! He concludes that there is something OTHER

>than jitter that affects the musicality of CD's. For the
>skeptics he says "I encourage anyone who asserts dogmatically
>and without a trace of doubt (a good description of my
>attitude at one time) that 'bits is bits' to listen with an
>open mind through a decent playback system to the effects of,
>say, CD Stoplight."

For all the pseudo-science in the article (fancy technobabble about
bit error rates, graphs, numbers, etc.) they fall flat on their face
by not at least doing a simple blindfold test to sanity check their
"disturbing conclusion".

Par for the course, naturally. I mean, surely if these silly tweaks
made such a striking difference then surely he could have been able
to correctly *identify* if a treated disk was playing or not?

Or am I missing the obvious here?

The real problem with this area is that there are a whole lot of people out
there who haven't a *clue* as to how things work in this world.

I'm talking simple first order common sense, the ability to estimate things
within a couple of orders of magnitude and so on. These people are going to
be easy targets for snake oil and patent medicine salesmen, and BS artists
writing for HIFI comics, who would like to convince them that they're being
real sophisticated and cool to believe this nonsense.

- Jim

Francis Vaughan

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Aug 7, 1990, 11:14:42 PM8/7/90
to

Gerp Harp mailed me a reply to some of the postings as his
NNTP server was acting up, ironicly his mail address makes my
mailer barf. This is further comentary.

-------------

OK, I try not to be a total cynic, I think perhaps there have been a
few misunderstandings and a few technical mess ups.

> I believe you misunderstood
> what I said. My disk has an error in the recorded data, which occured
> somewhere along the line. This error causes every player I have heard it
> on (quite a few, esp. high end) to try an make up for it, failing miserably
> and making a distortion-like noise. Putting "greep goop" on the edges of
> the disc made an AUDIBLE difference at that point. Anyway, read what I
> had to say to this guy.

You still must be very careful about this. If you assert the fault is in the
data stream and not in the player it is only physicly possible
for the green goop to have helped in fixing C2 (uncorrectable) errors off the
disk. Any other sort of damage to the signal (such as you suggested may have
come from a too-close mic position etc.) is irrevocably locked into the bits.
It is entierly possible that there is a C2 error or two on your disk and
that the goop may help fix these, but these only last for a few milli seconds.

> You sound like the same kind of cynics that opposed oversampling
filters on CD
> players because it was someone's wild idea!

On the contary, the moment the first CD players came out, I was already
thinking
about ways to build oversampling systems, and was down at my local hi-end
vendors shop explaining what I forsaw in the high end. I am glad to say that
I was very accurate. The new Krell CD player is precisly what I described
five years ago.

> What kind of grades did you make in physics?
Very good ones. Lets try not to get too personal.

> You see, a CD players uses a laser to read the data on the disk. Lasers are
> light beams. Light beams REFRACT when they are projected into dense objects,
> such as plastic. Due to refraction and internal reflection, the beams can
> interfere. One of the places where this internal reflection can occur the
> most is the edge!

No argument here, except for the "most" in the last sentence. This is
unsubstantiated. It might be true, but is not in any way substantiated.

> Now, since a silicon-based laser tends to have long wavelength, we can
consider
> it to be RED (although it's beyond the visible range). Now, something GREEN
> won't reflect a ray of light in the RED area! Amazing, huh?

No, we can't consider it to be red. The reflectivity of a substance in the
infra-red is NOT dependant upon its properties in the visible. Water strongly
absorbs some infra red wavlengths, but is transparent in the visible. Whereas
the goop MIGHT have a very low absorbtion at the appropriate wavelength the
fact that it is green to the human eye has very little to do with it.

Be very careful here. You might be arguing from the idea that green is the
complementary colour to red (it sounds as if you may be). Remember that
complementary colours are an artifact of the human visual system and have
no equivalence in spectroscopy. We are concered with only one thing,
the absorbtion of the goop at one, and only one wavelength. Why choose
green goop? Surely blue would be better? How about black? Green ironicly could
be a bad choice since the middle of green is about 450nm, which is about
double the 900nm of a typical IR semiconductor laser. Hence it might be a
very good refector.

> Now, painting the edge of a disc an opaque green will greatly cut the
> internal reflection of the beams. Hence, less errors.

This is a "maybe" with a "could be" with an "if". Not a "will" and "hence".

> This all leads to the result that my disc with a large error on it now plays
> as though the error is much smaller.

What is the error? That really is the crux of the argument. You continually
cite a nebulous error. The whole point of the many rebuttals and
citations of the mechanisms of the CD chain is to show that ONLY C2 errors
can be created in the disk reading mechanism. If there is some dammage to the
data in earlier processing the only thing your goop will do is allow us
to hear it unsullied by C2 errors. C2 errors either exist or not. The number
may reduce but each error cannot be "lessened".


> You can't tell me that the green paint did nothing to my disc. I and three
> other people (this test was done in a professional listening room using
> pretty high end audio) all heard the difference. This could not be accounted
> to cleaning, since I had already cleaned this CD more than once for the same
> reason.

Very possibly it did change the playback charateristics. But I and many others
dispute the reasons advanced. It CANNOT change the data stream. There has been
some discussion about jitter in the playback chain, and IF the goop lessens
errors in reading and results in fewer C1, (correctable errors) than maybe
the jitter in the DAC will be reduced. This will have NOTHING to do with the
recording or digital transcription process. It may have something do do with
the pressing. Mostly it is in the CD player.

You should try it on the SONY top end CD player (CDP-R1). It has a master
clock in the DAC, NOT in the disk reader, a design specificly designed to
eliminate the jitter outlined.

Next you MUST try a double blind trial. Two disks, same batch number and
an operator that doesn't know which disk is which. Also clean the goop off
and goop the ungooped one half way through the trial too. Hard but the only
valid proof.

It would be instructive to know what the error rates off your disk are.
If you do have a disk with a huge number of C1 errors and the goop does
lessen them then the world may sit up and listen.

Francis Vaughan

Francis Vaughan

unread,
Aug 8, 1990, 2:21:22 AM8/8/90
to
In article <13...@ulysses.att.com>, g...@ulysses.att.com (Griff Smith) writes:
|> In article <529...@hpscdc.scd.hp.com>, ev...@hpscdc.scd.hp.com (Evan

Whitney) writes:
|> > The difference is in the power supply. On my CD player (Magnavox 650)
|> > when the correction circuit kicks in, there is a slight drain on the
|> > power supply that produces an audible noise in and of itself,
|>
|> I believe you, but I doubt that it's the error correction logic; the
|> logic is running all the time anyway. You probably have a warped
|> disk.

... description of servo mechanism wrecking power supply.

Very good point. One that I had forgotten. There is no such thing as error
correction as a seperate activity. A stream of bits is sucked into the system
and a stream of values spat out. The redundancy information is ALWAYS
interpreted,
as it is this that allows the system to detect the error in the first place.
Only when the error is unrecoverable does any change in the system occur.

Francis Vaughan

logan shaw

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Aug 7, 1990, 1:28:45 PM8/7/90
to
In article <11...@alice.UUCP> a...@alice.UUCP (Andrew Koenig) writes:

>In article <35...@ut-emx.UUCP>, ls...@walt.cc.utexas.edu (logan shaw) writes:
>
>> All this leads me to an interesting question: in common practice, how
>> much of the data really _is_ misread off the CD?
>
>The design criterion for the system is 1 uncorrected error
>per month of continuous playback.

How close do CD players come to this in practice? Do most of them
attain this? Few of them?

If few of them actually attain this, then these treatments are worth
something, but if a fairly decent CD player (say $400 or so) meets the
spec, then all these treatments only make sense for flawed CD's.

>--
> --Andrew Koenig
> a...@europa.att.com


============================================================================
"The beauty queen, clevely clad, Logan Shaw
admires herself in a cigarette ad. ls...@ccwf.cc.utexas.edu
Will she admit that all was in vain ========================
when the face in her mirror cracks like a windowpane?"
-Elim Hall, _Things_Break_

Timothy G. Avery

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Aug 7, 1990, 12:20:48 PM8/7/90
to
Armor All makes my CD's sound 5000% better !!!!

Sorry, I had to do it....:-)

Timothy G. Avery

unread,
Aug 7, 1990, 12:25:17 PM8/7/90
to
In article <1990Aug6.2...@cbnewsh.att.com> yo...@cbnewsh.att.com (young.u.huh) writes:
>
>Perhaps someone could do a statistical study on this "phonomena."
>The results may be interesting.

Someone already knew someone who did this just as you described and posted the
results just a few days ago. You must have missed that one.

Tim

Sture Jonsson

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Aug 8, 1990, 4:34:07 AM8/8/90
to
In article <6704.2...@umiami.miami.edu> ch...@umiami.miami.edu writes:
>One of my professor's here, Ken Pohlmann ...

<Interesting "CD tweak" test report>

>make any CD sound better! The power of suggestion can be great!

I don't want to trash your test report (which sounded quite interesting to me),
and I definitely do not have any real opinion on CD tweaks.

But what I want to say is that when conducting tests one has to be fully aware
of the possibility of the suggestion working both ways. That is, it is fully
possible that people "hear" things just because they want to, but it is also
VERY MUCH a possibilty that people DON'T hear things because they don't want
to !

Probably it's much more common to hear things that don't exist, but there still
is a possibility of the opposite.

> Chuck Urwiler University of Miami Music Engineering Voice & Keys

Listen and enjoy
sture

Henry Kautz

unread,
Aug 7, 1990, 2:57:52 PM8/7/90
to
The most recent issue of Stereophile (August?) is quite amusing, as it
contains a large number of letters from people whose CD players have
been damaged by Armor All, which sublimates onto the the laser, and a
warning that the Green Marker treatment is also dangerous, because it
eventually flakes off and can damage the mechanism.

The best thing about this whole episode is that it may have convinced
a lot of people to stop reading Stereophile (sorry, no re-subscription
from me!), stop fussing with and wasting their money on stupid "hi fi
tweaks", and GET A LIFE.
--

---- Henry Kautz

:uucp: allegra!kautz
:arpa/internet: ka...@allegra.att.com
or ka...@research.att.com
:csnet: kautz%research...@RELAY.CS.NET
:old csnet: kautz%all...@btl.csnet

Alain Picard

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Aug 7, 1990, 12:59:17 PM8/7/90
to
In article <529...@hpscdc.scd.hp.com>, ev...@hpscdc.scd.hp.com (Evan Whitney) writes...

>>WHAT DIFFERENCE does it make how many errors are picked up by the
>>error checking circuit? That's precisely what it's there for!
>>You can make a mistake on every single bit, if you correct it,
>>you still have the same information. Not ONE BIT less.
>
>Wrong. The difference is in the power supply. On my CD player (Magnavox 650)
^^^^^^ Really ?

>when the correction circuit kicks in, there is a slight drain on the
>power supply that produces an audible noise in and of itself, let alone
>its effect on the intended audio portion. For most CDs this is not a
>problem and goes unnoticed. [ + more deleted stuff]

Ah. So now it's not the bitstream but the power supply... And you
want me to believe that there's a chip in the player that's not
powered up until it's needed (!?) If this is true, may I suggest
you go buy a nice, cheap $120 Technics CD player just like mine,
it doesn't seem to suffer from the strange problems you describe...
Cheers, ap

Oh, and someone posted a long harangue about how unscientific we
all were because we were judging this stuff **WITHOUT EVEN LISTENING!!**

If someone tells me that by throwing a ball at 100 m/s up in the air,
I can send it to the moon, I don't need to try it to find out that's
wrong, do I? Proper scientific method does NOT mean that I have to
debunk everything which contradicts established theories. Let the
people with the unconventional theories (green paint, etc) establish
the proper scientific tests, then I'll listen. (Hell, I may even
take part in the test if they want!)

Bill Oliver

unread,
Aug 7, 1990, 2:39:09 PM8/7/90
to

I've used this product and have done single blind listening
tests with it and have concluded it not only works but it's
AMAZING. Don't talk about things you know nothing about.

Bill

Evan Whitney

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Aug 8, 1990, 12:50:15 PM8/8/90
to
>/ hpscdc:rec.audio / g...@ulysses.att.com (Griff Smith) / 3:54 pm Aug 7, 1990 /

>>In article <529...@hpscdc.scd.hp.com>, ev...@hpscdc.scd.hp.com (Evan Whitney) writes:
>> The difference is in the power supply. On my CD player (Magnavox 650)
>> when the correction circuit kicks in, there is a slight drain on the
>> power supply that produces an audible noise in and of itself,

>I believe you, but I doubt that it's the error correction logic; the


>logic is running all the time anyway. You probably have a warped disk.

I don't think it was warped. I replaced it 5 times over a six month period,
and each disc caused the same high-pitched whine from the CD player, not
the speakers. I have 989 CDs in my collection. This one (Nu Shooz
_Told You So_) is the only one that causes this phenomenon. I believe that
the player is either attempting to correct thousands of errors per second,
or the servo is having a difficult time staying on track. One of the CDs
did indeed skip a couple of times.

I have stopped looking for a decent copy, as I have come to the conclusion
that the flaw exists in the master, and I don't think the music is that
good anyway. It would be interesting to hear if anyone else has this CD
and has experienced this wonderful sound.

Evan

jj, like it or not

unread,
Aug 8, 1990, 1:35:29 PM8/8/90
to
In article <7...@ria.ccs.uwo.ca> l...@rrivax.rri.uwo.ca writes:
>what happens in her brain. Tricky part is that as she was growing up, mom and
>dad would point at the grass and say "look, it is GREEN" and this person grows
>up calling RED,GREEN and calling GREEN,RED.
Aw, come on, Lance, you can do better than that. The proper response
which most any third-grader could give to you, is "so, what?" followed
by "looks OK to me".

I was going to refute this with some information on why neurons grow the
way they do and how the lateral geniculate works, but it occurred
to me that "He who argues with a fool...".

>esmith> We probably can't make transducers with the same response as the human
>esmith> ear,
>
>yes, one of my points was that i do NOT think that a transducer made by
>homosapien hands is capable of acting exactly the same as an ear.
So what? Everyone's ears are different, in fact more different than
a transdcer matched to one particular ear. (of course, you would
have to dissect that ear, which is a wee problem, in order to get
the particular basilar membrane sstructure...)

>esmith> but if we have two audio signal paths (A and B) to compare, and can
>esmith> determine that A presents a more accurate version of the source signal
>esmith> to the ear than B, we can conclude that the perception of A will be
>esmith> closer to the perception of the source than B will.
>
>no no no.
Yes, yes, yes. I tell you three times.

>we are "probably [unable to] make transducers with the same response as
>the human ear," thus we are unable to measure in exactly the same way.
"thus..." Wrong. Completely wrong. Illogical, and rhetorically
bankrupt to boot.
>If we
>are unable to measure the same way, then we are unable to guess at which, A
>or B is the most 'accurate' to the ear.
Not true. The sensitivities of the ear are very well known these
days. (not perfectly, but that's not relevant) Please see
the various papers in ASSP, AES, and elsewhere talking about
"perceptual coding" or "psychoacoustic coding", and THEN come back
and lecture us as an expert. Until then, spare us the
draconian pronouncements of impossibility.

>personally, i am still wondering how to handle treated CD's _without_
>getting green marker goop all over fingers.
Try a paper towel to wipe off the religious ink.

Before you rave about "jitter", go learn what it is. Before you
rave about "errors", go learn the facts.

Come to think of it, BEFORE YOU MAKE INCORRECT, PROVOCATIVE statements
that attack the entire base and implementation of scientific method,
go learn the facts.
--
Rince *Copyright alice!jj 1990, all rights reserved, except
Philib *transmission by USENET and like free facilities granted.
'A *Said permission is granted only for complete copies that
Choeil *include this notice. THIS MEANS YOU.

David Friedlander

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Aug 8, 1990, 4:42:36 PM8/8/90
to
In <7...@ria.ccs.uwo.ca> l...@rrivax.rri.uwo.ca (Lance R. Bailey) writes:

>In article <ESMITH.90...@goofy.apple.com>, esm...@goofy.apple.com (Eric Smith) writes...


>> If we can assume for that what a human hears is a function of the audio
>> signal arriving at his or her ears, then we should be able to determine
>> whether two audio signals will be percieved the same by measuring the
>> signals with a transducer that has the same response as the ear. What
>> happens after the ear (i.e., in the brain) is then irrelevant unless it
>> depends on factors other than the audio.

>I disagree. what happens in my brain is unknown to me, you and everyone else.
>Take the following example. Let us say that there is a person with a
>certain type of colour perception problem. All her life she sees green as
>red (and vice versa). That is, the slice of the spectrum that induces "GREEN"
>in everyone elses mind induces RED in her mind (and vice versa). This 'problem'
>is not due to a mis firing of the three cone types in her eyes, but rather


>what happens in her brain. Tricky part is that as she was growing up, mom and
>dad would point at the grass and say "look, it is GREEN" and this person grows
>up calling RED,GREEN and calling GREEN,RED.

>To all outward appearences, this person sees RED as RED and GREEN as GREEN
>but in her mind, things are completly reversed.

I don't think this is a realistic example of the way color-blindness works.

>the point is that two EXACTLY the same inputs are being perceived completly
>different by the brain and there is no way to tell that.

I think you have missed Eric's point here: If I show you a lawn of green
grass and a *photograph* of the same green lawn, if the photograph is
properly doing its job, then you should have no trouble identifying it as
the same color grass. I don't care *how* you perceive it, so long as you
make the connection that we are observing the same object in two forms.

Note that I am not talking about showing you August-burned-out brown
grass as compared to a photo of green grass.

As has been pointed out here before, audio (live or reproduced) is
comprised of sound waves that conform to very well-understood laws of
physics. Unless you can show that there is a difference between those
two types of sound, then I don't care (in this context) what your
perception is. If I am providing you with the same input, it should
produce the same results.

One other example: (anyone know a source for this?)
The human eye originally sees an inverted image, which the brain
subsequently inverts. An experiment was done (several) years ago in
which subjects were outfitted with glasses made of prisms which inverted
the images they saw. For the first few days, they went around bumping
into things, before their brains stopped inverting the image (or inverted
it again?) so that they could see normally. (Later, they had the same
adjustment problems when the lenses were removed!)
During the experiment, the processing that their brains were doing
was very different from you and me, but the world *looked the same* !

This is the same as your example *EXCEPT* that yours complicates matters
by including human labels ("dad would point at the grass and say "look, it
is GREEN"").

David Friedlander d...@sage0.gsfc.nasa.gov
NASA/ Goddard Space Flight Center
Greenbelt, MD 20771 Gamma Ray Observatory

Tom Pohorsky

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Aug 8, 1990, 5:00:49 PM8/8/90
to
In article <58...@darkstar.ucsc.edu> so...@ucscb.UCSC.EDU (Alan Waterman) writes:
>The person who posted it meant it as a joke and couldn't believe ...

Not meant as a flame:

There is some significant amount of people that beleive in the green effect
out in the real world, independent of what goes on on USENET. The discussion
is more than just a rec.audio in-joke. Personally, I'm pretty skeptical, but
just note that life does not imitate the net.

regards, tomp.
--
ames!vsi1!tomp to...@vicom.com

Griff Smith

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Aug 7, 1990, 6:54:48 PM8/7/90
to
In article <529...@hpscdc.scd.hp.com>, ev...@hpscdc.scd.hp.com (Evan Whitney) writes:
> The difference is in the power supply. On my CD player (Magnavox 650)
> when the correction circuit kicks in, there is a slight drain on the
> power supply that produces an audible noise in and of itself,

I believe you, but I doubt that it's the error correction logic; the


logic is running all the time anyway. You probably have a warped

disk. This might make the tracking servo power supply work overtime
trying to keep the laser assembly focused on the track. I have a few
discs that make my player click, and the sound is a lot louder when I
try to play a defective disc. I can't imagine how green snake oil
could help improve the shape of a bent disc (though I'm sure some of
you can invent some theories).
--
Griff Smith AT&T (Bell Laboratories), Murray Hill
Phone: 1-201-582-7736
UUCP: {most AT&T sites}!ulysses!ggs
Internet: g...@ulysses.att.com

Alain Picard

unread,
Aug 7, 1990, 10:25:35 PM8/7/90
to
In article <66...@sgi.sgi.com>, bol...@ozone.vlsi.sgi.com (Bill Oliver) writes...

Excuse me, but what is a "single blind listening test" ?
To do a blind test, you need at least 2 people,
one to throw a dice (or other random number generator) and flip
a switch, and one to listen and decide if what he hears is A or B.

ap

Lance R. Bailey

unread,
Aug 8, 1990, 1:43:03 AM8/8/90
to
In article <ESMITH.90...@goofy.apple.com>, esm...@goofy.apple.com (Eric Smith) writes...
>In article <7...@ria.ccs.uwo.ca> l...@rrivax.rri.uwo.ca (Lance R. Bailey) writes:
..
lrb>
lrb> The listening process involves
lrb> not
lrb> only the ear (again, a basically mechanical device) but your mind and it's
lrb> interpretation of the signal passed to it. Thus, there is a host of
lrb> psychological effects/affects which control the listening experience.
..
esmith>
esmith> If we can assume for that what a human hears is a function of the audio
esmith> signal arriving at his or her ears, then we should be able to determine
esmith> whether two audio signals will be percieved the same by measuring the
esmith> signals with a transducer that has the same response as the ear. What
esmith> happens after the ear (i.e., in the brain) is then irrelevant unless it
esmith> depends on factors other than the audio.

I disagree. what happens in my brain is unknown to me, you and everyone else.
Take the following example. Let us say that there is a person with a
certain type of colour perception problem. All her life she sees green as
red (and vice versa). That is, the slice of the spectrum that induces "GREEN"
in everyone elses mind induces RED in her mind (and vice versa). This 'problem'
is not due to a mis firing of the three cone types in her eyes, but rather
what happens in her brain. Tricky part is that as she was growing up, mom and
dad would point at the grass and say "look, it is GREEN" and this person grows
up calling RED,GREEN and calling GREEN,RED.

To all outward appearences, this person sees RED as RED and GREEN as GREEN
but in her mind, things are completly reversed.

the point is that two EXACTLY the same inputs are being perceived completly


different by the brain and there is no way to tell that.

esmith> We probably can't make transducers with the same response as the human
esmith> ear,

yes, one of my points was that i do NOT think that a transducer made by
homosapien hands is capable of acting exactly the same as an ear.

esmith> but if we have two audio signal paths (A and B) to compare, and can
esmith> determine that A presents a more accurate version of the source signal
esmith> to the ear than B, we can conclude that the perception of A will be
esmith> closer to the perception of the source than B will.

no no no.

we are "probably [unable to] make transducers with the same response as

the human ear," thus we are unable to measure in exactly the same way. If we


are unable to measure the same way, then we are unable to guess at which, A
or B is the most 'accurate' to the ear.


esmith> Note that this says nothing about which sounds "better".
nor, will you note, did (or does) mine. :-)

personally, i am still wondering how to handle treated CD's _without_
getting green marker goop all over fingers.

_________________________________

Steve Kanefsky

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Aug 8, 1990, 9:42:00 AM8/8/90
to

A single blind listening test is when the subject doesn't know which
source he or she is listening to.

A double blind test is when neither the subject nor the person performing
the test knows which is which.

It's possible in a single blind test that the person performing the test
might subconsciously communicate to the subject which player is which
(e.g. by facial expressions).


--
Steve Kanefsky
kane...@cs.umn.edu

ch...@umiami.miami.edu

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Aug 8, 1990, 11:25:11 AM8/8/90
to

Yep. I was the one who posted it. Check your backlogs. It's under the
same subject heading as all of these articles.
--

Chuck Urwiler University of Miami Music Engineering Voice & Keys

===========================================================================
chuck@umiami -or @umiamivm (Bitnet) | "Sometimes the one thing that you're
ch...@umiami.miami.edu (Internet) | looking for, is the last thing on
ch...@miavax.ir.miami.edu (Internet) | your mind" -Robbie Nevil
===========================================================================
Disclaimer: I only work and learn at this University. I don't speak for it!

William Kucharski

unread,
Aug 8, 1990, 12:51:28 PM8/8/90
to
In article <KAUTZ.90A...@adhoc.allegra.att.com> ka...@allegra.att.com writes:
>The most recent issue of Stereophile (August?) is quite amusing, as it
>contains a large number of letters from people whose CD players have
>been damaged by Armor All, which sublimates onto the the laser, and a
>warning that the Green Marker treatment is also dangerous, because it
>eventually flakes off and can damage the mechanism.

Please get your facts straight. There are several letters from people who
assert their CDs sound better/worse/are now damaged from the application of
Armor All, but the player report is from the front of the magazine. It seems
that the Audio Anarchist, Sam Tellig, pulled this month's article because he
has heard reports that CD Stoplight can gum up the works of some CD players when
the green paint flakes off the CD edge and into the player's innards. As a
matter of fact, he recommends that consumers stay away from CDs _period_ until
we figure out why CD Stoplight helps at all and how CDs "should" be made.

Granted, Stereophile is often thought provoking and even sometimes infuriating,
but since I don't get into Harry Pearson's ramblings in TAS, Audio is only
somewhat useful and Stereo Review -- well, is Stereo Review, Stereophile is the
best choice, IMHO.

--
===============================================================================
| Internet: kuch...@Solbourne.COM | William Kucharski |
| uucp: ...!{boulder,sun,uunet}!stan!kucharsk | Solbourne Computer, Inc. |
=== The sentiments expressed above are MY opinions, NOT those of Solbourne. ===

Tim Bray

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Aug 8, 1990, 10:53:53 PM8/8/90
to
kane...@cs.umn.edu (Steve Kanefsky) writes:
>A single blind listening test is...
>A double blind test is...

>It's possible in a single blind test that the person performing the test
>might subconsciously communicate to the subject which player is which
>(e.g. by facial expressions).

Not just possible; there have been totally incontrovertible demonstrations
of this effect, even when (a) the experiment controller has little
direct contact with the subject, and (b) the experiment controller has
little emotional investment in which way the experiment comes out. Moral
of the story; human beings communicate efficiently with each other, even
in the apparent absence of volition. You have to take active measures to
stamp this out.

Cheers, Tim Bray, Open Text Systems

jj, like it or not

unread,
Aug 9, 1990, 3:03:48 PM8/9/90
to
In article <37...@vrdxhq.verdix.com> bi...@vrdxhq.verdix.com (William Spencer) writes:

>Essentially, yes. Practically, not so easy. One difference between measuring
>and hearing is that different sounds are heard as unrelated. The presence of
>400 Hz at 110 dB doesn't prevent hearing 2222 Hz at 10 dB. The 2222 Hz
>would only be visible on the highest resolution of oscilloscopes.
Excuse me, but perhaps you should look into the subject matter before
you make absolute assertions. Your 2222 Hz signal is about 9.5 critical
bands away from your 400 Hz signal. Were your loud signal a lower level,
the 2222Hz signal would be unmasked, although not very audible,
however, given your absolute level, the spreading function due to
the cochlear filter separation starts to get much larger,
in fact, to about 10dB/critical band (or less!). I.e. the JND for your
2222Hz signal would be about 95dB below the 400Hz signal,
or 110-95=15dB, ergo even using a quite conservative analysis,
your signal would be inaudable. In practice, of course, the
distortion from the best existing transducer would easily mask
your 2222Hz signal.

In other words, you're close, but still substantially wrong.
These well-known effects can be found in Tobias's book,
"Fpoundations of Modern Auditory Cheory", Academic Press,
NY, 1970, for instance. Also check out a 1979 ASSP
paper (sorry, the citation isn't right next to me) by
Schroeder, Atal, and Hall on Psychoacoustic Coding,
as well as Brandenburg, K, "High quality sound coding at 2.5 bits/sample",
84th AES Convention Paris 1988, Johnston and Brandenburg "Second Generation
Perceptual Audio Coding: The Hybrid Coder", 88th AES Convention,
Montreux, 1990, Johnston, J. D, "Transform Coding of Audio Signals
Using Perceptual Noise Criteria", JSAC, 1988 Vol. 6, pp314+,
Theile, G (et al), "MASCAM: Low Bit rate coding of high quality audio
signal, and introdction tot he MASCAM system", EBU Review, No. 230.
and many others.

>A spectrum analyzer could also be used. You'd have to know what you're looking
Nothing else but spectrum analysis SHOULD be used, a scope is useless
for such measurements. In fact, you even need a smart spectrum
analyzer. Such exist. I'm sitting next to one. Not only that,
my FX80 has even smarter analyzers, such as specified by Brandenburg
in "Evaluation of quality for audio encoding at low bit rates" 82nd AES
convention, London 1987,as well as one based on Johnston's paper
above (with many proprietary modifications that make it much,
much better than any in the literature. Simple enough to do if
you study the art instead of making draconian pronouncements.

>for. But this is still simple compared to music. Distortion may occur only
>on transient signals with bizarre waveforms. The only way to analyze
So what? Use enough test material.
>differences could be a null test, subtracting one signal from the signal to be
>compared. This is difficult with some comparisons, for example comparing
>CD's, because the signals have to be synchronized with one another.
A null test is completely meaningless. Since you take the difference
and present it alone, you have no comprehension if the distortions
you hear would be masked by the signal.

Given that the typical music signal can be perceptably identical
to the original with a 20dB SNR, your test is meaningless. (See
above references, also the upcoming Sweedish Radio report
on ISO-MPEG testing, for instances.)

The ear really can't hear very much at all, it's just good
at a specific set of tasks. Eventually you'll all have to
accept that.

Greg Harp

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Aug 9, 1990, 2:34:25 AM8/9/90
to

greg...

_ _ Disclaimer: "What I _really_ meant was..."
AMIGA! ////
//// "Run to the bedroom, in the suitcase on the left you'll find my
_ _ //// favorite axe." --Roger Waters, Pink Floyd's The Wall, One of My Turns
\\\\////
\\XX// Greg Harp gr...@ccwf.cc.utexas.edu

Derrick Rowlandson

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Aug 9, 1990, 12:35:02 AM8/9/90
to

What I don't understand, is that if there is ANY truth to this,
(and there appears to be), why isn't this taken care during the
manufacturing process?

Derrick
--

der...@cs.AthabascaU.CA

Greg Harp

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Aug 9, 1990, 2:53:35 AM8/9/90
to
In article <34...@lulea.telesoft.se> st...@lulea.telesoft.se (Sture Jonsson) writes:
>In article <6704.2...@umiami.miami.edu> ch...@umiami.miami.edu writes:
>>One of my professor's here, Ken Pohlmann ...
><Interesting "CD tweak" test report>
>>make any CD sound better! The power of suggestion can be great!

>I don't want to trash your test report (which sounded quite interesting to me),
>and I definitely do not have any real opinion on CD tweaks.
>But what I want to say is that when conducting tests one has to be fully aware
>of the possibility of the suggestion working both ways. That is, it is fully
>possible that people "hear" things just because they want to, but it is also
>VERY MUCH a possibilty that people DON'T hear things because they don't want
>to !
>Probably it's much more common to hear things that don't exist, but there still
>is a possibility of the opposite.

In fact, I'm willing to put money on the fact that most CD tweaks (including
the green goop) produce results that are mostly psychosomatic. Since I
advocate the green goop theory, I pursue it hoping to see it proved. That
way I can be sure that what I hear is an actual improvement, instead of a
supposed one. The point is that I believe that it sounds better, therefore
it does -- to me. Other don't believe it, and they don't hear any difference.

Music was intended to be listened to for enjoyment, was it not? Reducing it
to statistics and facts removes the _art_ of the recording. If something
sounds better to you, then screw everybody else's opinion. After all, they
didn't pay for your system or your recording, and they don't listen to your
equipment either.... Where does someone else get off telling others how
they should enjoy their music?

>> Chuck Urwiler University of Miami Music Engineering Voice & Keys
>
>Listen and enjoy
>sture

Eric Smith

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Aug 8, 1990, 6:25:10 PM8/8/90
to
In article <7...@ria.ccs.uwo.ca> l...@rrivax.rri.uwo.ca (Lance R. Bailey) writes:

In article <ESMITH.90...@goofy.apple.com>, esm...@goofy.apple.com (Eric Smith) writes...

..
lrb> The listening process involves not


lrb> only the ear (again, a basically mechanical device) but your mind and it's
lrb> interpretation of the signal passed to it. Thus, there is a host of
lrb> psychological effects/affects which control the listening experience.
..
esmith> If we can assume for that what a human hears is a function of the audio
esmith> signal arriving at his or her ears, then we should be able to determine
esmith> whether two audio signals will be percieved the same by measuring the
esmith> signals with a transducer that has the same response as the ear. What
esmith> happens after the ear (i.e., in the brain) is then irrelevant unless it
esmith> depends on factors other than the audio.

lrb> I disagree. what happens in my brain is unknown to me, you and everyone else.
lrb> Take the following example. Let us say that there is a person with a
lrb> certain type of colour perception problem. All her life she sees green as
lrb> red (and vice versa). That is, the slice of the spectrum that induces "GREEN"
lrb> in everyone elses mind induces RED in her mind (and vice versa). This 'problem'
lrb> is not due to a mis firing of the three cone types in her eyes, but rather
lrb> what happens in her brain. Tricky part is that as she was growing up, mom and
lrb> dad would point at the grass and say "look, it is GREEN" and this person grows
lrb> up calling RED,GREEN and calling GREEN,RED.
lrb> To all outward appearences, this person sees RED as RED and GREEN as GREEN
lrb> but in her mind, things are completly reversed.
lrb> the point is that two EXACTLY the same inputs are being perceived completly
lrb> different by the brain and there is no way to tell that.

I agree with what you are saying here; when I was a child I used to ask
people about this, with the inevitable response "what difference would it
make." You miss the point of what I was trying to say. I didn't say two
different people would perceive the same stimulus in the same way.

I said that one person would perceive the audio from signal path A in the
same way he/she would perceive the audio from signal path B, if both
signal paths produce the same stimulus to the ear. Therefore if we can
measure the characteristics of the stimulus from signal path A (without
green goop) and the stimulus from signal path B (with green goop), we can
tell whether they will be perceived the same. This has nothing to do with
the processing that the brain does after the ear, unless (1) the processing
in non-reproducible, or (2) the processing is significantly influenced by
factors other than the sound (air pressure waves).

If case 1 is true, there is no reason to even discuss the subject.

If case 2 is true, we must take care to

What we both agree on is that we can't currently determine exactly and in
complete detail what part of the stimulus is significant to human hearing.

I claim, however, that we can approximate the response of the ear arbitrarily
closely. It is a foregone conclusion that no measurement is ever "exact".

I won't argue whether the goal of high-fidelity reproduction is to replicate
the source sound as closely as possible, but if I want a specific effect, it
is much easier to achive the effect by specifically designed processing after
a transparent record/playback process than after a record/playback process
that modifies the sound. Therefore I want the signal out of my CD player to
be as close to identical to the signal that went into the mastering system as
is technologically possible. If green goop on the CD is necessary to
accomplish this, then by all means we should use it. I am just arguing that
it should be possible to tell whether they make a perceptible difference to
the listener by measuring the stimulus to the ear.

Of course, unless there is some inexplicable, magic in the signal path between
the CD player output and the ear, it should be possible to conduct an
experiment to determine whether the waveform from the CD player is closer to
the original with or without green goop on the CD. If something other than
the electrical waveform out of the CD player affects the listeners perception
when all other parts of the signal path are identical (amp, speakers, room,
etc.), then all bets are off.

esmith> We probably can't make transducers with the same response as the human
esmith> ear,

lrb> yes, one of my points was that i do NOT think that a transducer made by
lrb> homosapien hands is capable of acting exactly the same as an ear.

Again, we can approximate arbitrarily closely. What's the point of trying to
be exact? No two human ears (even the same person's) are identical anyhow.

esmith> but if we have two audio signal paths (A and B) to compare, and can
esmith> determine that A presents a more accurate version of the source signal
esmith> to the ear than B, we can conclude that the perception of A will be
esmith> closer to the perception of the source than B will.

lrb> no no no.
lrb> we are "probably [unable to] make transducers with the same response as
lrb> the human ear," thus we are unable to measure in exactly the same way. If we
lrb> are unable to measure the same way, then we are unable to guess at which, A
lrb> or B is the most 'accurate' to the ear.

Although we may not understand ALL of the subtleties of the human ear, we
can model it functionality well enough that certain changed in a signal will
have known effects to the perceived sound. Therefore if the signal varies
enough that known effects will occur, we CAN determine which signal is more
accurate. As the model aproaches reality, the smaller or more subtle a
change in the signal can be compared.

lrb> personally, i am still wondering how to handle treated CD's _without_
lrb> getting green marker goop all over fingers.

But you want to get green marker goop on your fingers! That makes the effect
even better! :-)

Personally, I think the whole green marker thing is a load of horse *$#^.
A salescreature played several CDs for me before and after applying the
marker, and although he seemed to hear an improvement, I certainly didn't.
No one has yet come up with a satisfactory answer as to how 'trapping' the
excess laser emissions is supposed to produce better sound. If they claim
to reduce the amount of error concealment, how is there going to be a
perceived improvement to any of my discs, which typically have zero to
two errors requiring concealment per disc? The concealment only affects
a few samples out of say 300 million on the disk.

If the green goop doesn't affect the bits coming from the disk (a testable
hypothesis), and doesn't affect the jitter of the signal (another testable
hypothesis), and doesn't affect the intensity of the optical output of my
disk player (yet another testable hypothesis), then is there any way it
could have an affect on my outboard D/A converter, which is connected via
optical cable?

I know! The green marker somehow causes the circuitry in the CD player
to work less hard (or harder), changing the load on the power supply.
This change in load affects the voltage regulator, bypass capacitors,
power supply filter capacitors and power supply transformer, changing
the load on our local electric company. The resulting minute variation
in line voltage is then coupled throught the transformer, capacitors,
regulator, etc. of my D/A converter into an audible difference in the
signal. That I can hear despite not being able to hear much larger
differences due to line voltage fluctuations caused by my neighbor's
air conditioner, refrigerator, and vacuum cleaner. I guess I'll have to
power my D/A converter from batteries. But what if the batteries are
receiving gravity waves from an alien civilization in the Andromeda
Galaxy?

Yeah, right! :-)

--
Eric L. Smith Opinions expressed herein do not necessarily reflect those
esm...@apple.com of my employer, friends, family, computer, or even me! :-)

Larry Spence

unread,
Aug 8, 1990, 7:36:31 PM8/8/90
to
I guess it's time for me to repost my article about how leaving your CD
player on autorepeat all night makes all the aluminum ooze out towards the
outer edge of the disk... %) %) %)

At least this thread gives me some idea what the half-life of readers of
rec.audio might be...

--
Larry Spence
larry@csccat
...{texsun,cs.utexas.edu,decwrl}!csccat!larry

William Spencer

unread,
Aug 8, 1990, 8:26:31 PM8/8/90
to
in article <12...@sirius.ucs.adelaide.edu.au>, fra...@cs.ua.oz.au (Francis Vaughan) says:
> It would be instructive to know what the error rates off your disk are.
> If you do have a disk with a huge number of C1 errors and the goop does
> lessen them then the world may sit up and listen.

Since COUNTING errors has already been done to no conclusion, it occurs
to me that tests should look for a different distribution of errors.
You could even hook up to the error correct signal and listen for a
difference.


bill S.

William Spencer

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Aug 8, 1990, 9:16:47 PM8/8/90
to

In article <ESMITH.90...@goofy.apple.com>, esm...@goofy.apple.com (Eric Smith) writes...
>
> If we can assume for that what a human hears is a function of the audio
> signal arriving at his or her ears, then we should be able to determine
> whether two audio signals will be percieved the same by measuring the
> signals with a transducer that has the same response as the ear. What
> happens after the ear (i.e., in the brain) is then irrelevant unless it
> depends on factors other than the audio.

Essentially, yes. Practically, not so easy. One difference between measuring


and hearing is that different sounds are heard as unrelated. The presence of
400 Hz at 110 dB doesn't prevent hearing 2222 Hz at 10 dB. The 2222 Hz
would only be visible on the highest resolution of oscilloscopes.

A spectrum analyzer could also be used. You'd have to know what you're looking

for. But this is still simple compared to music. Distortion may occur only
on transient signals with bizarre waveforms. The only way to analyze

differences could be a null test, subtracting one signal from the signal to be
compared. This is difficult with some comparisons, for example comparing
CD's, because the signals have to be synchronized with one another.

bill S.

David J. Finton

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Aug 9, 1990, 10:53:01 AM8/9/90
to
In article <529...@hpscdc.scd.hp.com> ev...@hpscdc.scd.hp.com (Evan Whitney) writes:
>>WHAT DIFFERENCE does it make how many errors are picked up by the
>>error checking circuit? That's precisely what it's there for!
>
>Wrong. The difference is in the power supply. On my CD player (Magnavox 650)

>when the correction circuit kicks in, there is a slight drain on the
>power supply that produces an audible noise in and of itself, let alone
>its effect on the intended audio portion. For most CDs this is not a
>problem and goes unnoticed. However, when a particularly marginal CD is
>played, the CD player produces a very annoying high-pitched whine that can be
>heard in the next room. (Check out Nu Shooz's _Told You So_ CD for an excellent
>example of this phenomemenon.)

How did you ascertain that the error circuit/power supply was responsible
for this noise? Were you able to measure the drain on the power supply?
Why would a drain on the power supply create an audible noise, anyway?

Couldn't the same thing be caused by bad servos controlling the laser's
focusing?

I've always heard about data errors muddying the soundstage or compressing
the dynamics, but never as resulting in a high pitched whine. Is the
noise constant, or does it fluctuate with the (assumed) stochastic
nature of the errors?

I have some CDs which have a high-pitched whine, although it doesn't
drive me out of the room. I always thought it was just an artifact
of a poor recording process. Has anyone else noticed this? I seem
to remember "Horowitz in Moscow" as having such a whine.

David Finton

Michael Hemy

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Aug 9, 1990, 11:21:12 AM8/9/90
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>From: jam...@wacsvax.uwa.oz (James Pinakis)
>
>I've heard from a somewhat unreliable source that if one colours the outside
>and inside edges of a CD with green (and I'm told it _has_ to be green
>or else it won't work) permanant felt pen, the CD will "sound better"
>and skip less. It's meant to have something to do with eliminating/reducing
>reflected light. . . .


Again misconception !! Reducing or eliminating reflected light, if it
were to occur, would only cause the sound to loose its warmth. As we
already know, the perfect flat acoustic response is not ,for everyone,
producing the best sound. Eliminating harmonic distortion is even a
better example of denying the sound its warmth. A very important
factor when listening to music, is the ambiance, which is governed by
the room's size and acoustics. This is why there is a growing market
for sound-processors, which add different delays to the signal to mimic
different listening environments.

How does all of the above relate to "Colouring CDs Green" ?
Very simply: Loosing additional reflections of the light beam is
compared to loosing acoustical delays in the original sound thus
making it sound dull.

The solution is to INCREASE the number of reflections !
This is done with the use of "sparkles" and "transparent glue".

1. Put some glue on the outer circumference of the CD.
2. Spread the sparkles particles on top.
3. Blow, to remove unglued particles.

Now ,relax and listen to the music. The sparkles act as tiny mirrors,
producing thousands of 'reflected delays'.
No wonder those sparkles are sometimes referred as "magic powder".
Now, the real trick is to master the quantity that needs to be spread,
depending on the required ambiance of-course. :*)

--Micky.

ch...@umiami.miami.edu

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Aug 9, 1990, 10:37:39 AM8/9/90
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In article <34...@lulea.telesoft.se>, st...@lulea.telesoft.se (Sture
Jonsson) writes:
> But what I want to say is that when conducting tests one has to be fully aware
> of the possibility of the suggestion working both ways. That is, it is fully
> possible that people "hear" things just because they want to, but it is also
> VERY MUCH a possibilty that people DON'T hear things because they don't want
> to !
>
> Probably it's much more common to hear things that don't exist, but there
> still is a possibility of the opposite.
>
> Listen and enjoy
> sture

I certainly agree with you, but I guess this means I didn't make my point very
clear. :-) I tried to give the impression that there were people in the room
that *wanted* to hear a difference, but they didn't. No one heard any
difference with the green goop on or off the discs. I would love to see a
bigger study of this, just to prove whether it's for real or not (I think it's
a crock, by the way).
--

Chuck Urwiler University of Miami Music Engineering Voice & Keys

Andrew Koenig

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Aug 9, 1990, 10:46:07 PM8/9/90
to
I wonder if people have tried coloring their ears green.

Or left out a saucer of green milk for the elves.
--
--Andrew Koenig
a...@europa.att.com

Alan Peterman

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Aug 10, 1990, 2:09:47 PM8/10/90
to
Whatever you may think of the sonic enhancements offered by coating the
edges of your CDs green (which I've tried and with careful listening found
perhaps a slight change), the latest ad from Audio Advisor raises the
question of price gouging. In the August AUDIO magazine, on page 87, is
a full page ad for many typical "audiophile" accessories such as feet,
tube traps, connectors, stands and so forth. What is new in this ad is
the "CD STOPLIGHT" which looks like a green marker and is labled as a
"green paint pen for CD treatment". The only remarkable feature is the
$14.95 price that is labeled "only"!

Are there really folks who will shell out $15 for a $2 marker that can
be gotten at any local store, and are even being given away free by some
audio shops? Are other "high-end" products similarily overpriced?

This seems to be somewhat common in audiophile products, the price must be
a "rip-off" to be a truely "high-end" product. Tube traps at $870,
speaker wire at $20 per foot, power cords for $250, interconnects at
hundreds of dollars. While I appreciate good equipment, and good quality,
some of this stuff and their prices are beyond comprehension. Guess some
folks don't care about value - and others love to prey on them.


--
Alan Peterman (503) 684-1984 (hm)
Airborne Cardinal RG N33291

Bob Myers

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Aug 10, 1990, 1:07:56 PM8/10/90
to
>In fact, I'm willing to put money on the fact that most CD tweaks (including
>the green goop) produce results that are mostly psychosomatic. Since I
>advocate the green goop theory, I pursue it hoping to see it proved. That
>way I can be sure that what I hear is an actual improvement, instead of a
>supposed one. The point is that I believe that it sounds better, therefore
>it does -- to me. Other don't believe it, and they don't hear any difference.
>
>Music was intended to be listened to for enjoyment, was it not? Reducing it
>to statistics and facts removes the _art_ of the recording. If something
>sounds better to you, then screw everybody else's opinion. After all, they
>didn't pay for your system or your recording, and they don't listen to your
>equipment either.... Where does someone else get off telling others how
>they should enjoy their music?

On the other hand, some of the "tweaks" which have been proposed over the
years for audio - including CDs - have been fairly expensive (some "audiophile"
cables, for example) or possibly *damaging* (the reputed effects of
"Armor-All-ing" your CDs). If the effects are "psychomatic," then someone
*should* object to people wasting their money or damaging their equipment out
of sheer ignorance. I assume that few of us have unlimited budgets, and that
we wish to invest what money we spend on audio in the best way possible. If
you really insist on spending money on a "psych" improvement, I suggest that
you'd do better spending it on a good hypno-therapist: "Your system sounds
G-O-O-D!!!! Your system sounds W-O-N-D-E-RRRRR-F-U_LLLL!"

Bob Myers KC0EW HP Graphics Tech. Div.| Opinions expressed here are not
Ft. Collins, Colorado | those of my employer or any other
my...@fc.hp.com | sentient life-form on this planet.

Greg Harp

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Aug 11, 1990, 1:48:35 AM8/11/90
to
In article <1803...@hpfcdj.HP.COM> my...@hpfcdj.HP.COM (Bob Myers) writes:
>On the other hand, some of the "tweaks" which have been proposed over the
>years for audio - including CDs - have been fairly expensive (some "audiophile"
>cables, for example) or possibly *damaging* (the reputed effects of
>"Armor-All-ing" your CDs). If the effects are "psychomatic," then someone
>*should* object to people wasting their money or damaging their equipment out
>of sheer ignorance. I assume that few of us have unlimited budgets, and that
>we wish to invest what money we spend on audio in the best way possible. If
>you really insist on spending money on a "psych" improvement, I suggest that
>you'd do better spending it on a good hypno-therapist: "Your system sounds
>G-O-O-D!!!! Your system sounds W-O-N-D-E-RRRRR-F-U_LLLL!"

Unfortunately, some people _do_ damage their equipment out of ignorance, but
then what do they blissfully ignorant think they're doing messing with
otherwise functional audio systems anyway? People who do not take the time
to research these things are asking for trouble.

As for damaging "tweaks": The original suggestion to use Armor-All was
accompanied by a disclaimer that it would speed CD deterioration.

As for high prices: Well, you often _do_ get what you paid for in high-end
audio. I personally can't afford a pair of B&W 801s, but I know they are
much better than my (rather nice, IMHO) $350 speakers.

Most tweaks are warranty-voiders too, but that doesn't stop most people. The
quest for better sound is a perpetual persuance of mankind.

As for the hypno-therapist: It'd probably work, too! :-)
I'd rather put the money into my audio system or (*gasp*) other things!

To restate my point: Unless _you_ are the owner of the audio system at hand,
you have no right to dictate what the owner does to make his/her system sound
the way he/she likes it. If someone wants to spend X amount of dollars on
equipment that may-or-may-not improve their system, then they have perfect
right to. What's important is how much they enjoy their music.

>Bob Myers KC0EW HP Graphics Tech. Div.| Opinions expressed here are not
> Ft. Collins, Colorado | those of my employer or any other
>my...@fc.hp.com | sentient life-form on this planet.

Sture Jonsson

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Aug 14, 1990, 2:52:38 AM8/14/90
to
In article <11...@alice.UUCP> j...@alice.UUCP (jj, like it or not) writes:
>The ear really can't hear very much at all, it's just good
>at a specific set of tasks. Eventually you'll all have to
>accept that.

Can your measurement devices say which one in an orchestra plays out of tune,
can it judge which of two performances are more enjoyable to listen to ?

Because things of that nature is all that really matters.

If so, I'd really like to see that (I mean it !).

Listen and enjoy
sture

Francis Vaughan

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Aug 14, 1990, 5:45:41 AM8/14/90
to
In article <1990Aug10.1...@techbook.com>, a...@techbook.com (Alan

Peterman) writes:
|> Are there really folks who will shell out $15 for a $2 marker that can
|> be gotten at any local store, and are even being given away free by some
|> audio shops? Are other "high-end" products similarily overpriced?
|>
|> This seems to be somewhat common in audiophile products, the price must be
|> a "rip-off" to be a truely "high-end" product. Tube traps at $870,
|> speaker wire at $20 per foot, power cords for $250, interconnects at
|> hundreds of dollars. While I appreciate good equipment, and good quality,
|> some of this stuff and their prices are beyond comprehension. Guess some
|> folks don't care about value - and others love to prey on them.

I think this is endemic in most high end stuff. Many bits are grossly
overpriced in comparison with their manufacturing cost. However one needs
to look at the source of many of these costs.

Monster cable and products are a good case study. My experience has been
that any of the monster products are all quite well made, and are all
a cut above off-the-self equivalents. However they tend to be about three
times the price of the off-the-self bits. There is no doubt that ordinary
monster cable is a good speaker cable, and all the discount clones are
inferior (mostly in quality of manufacture, things like ease of soldering,
quality of finish, I make no claims about "golden eared" suble sonic
differences).

Monster interconnects I think are (were actually, I haven't tried any in
about three years) very nicely made balanced cables, that are really a lot
nicer than the garden variety Belden et. al. cables. I could easily belive
that Monster interconnects would be preferable. However this is again based
soley on quality of construction, things like nice insulation, lots of copper,
nice screens, careful packing of the strucure. However, how it gets to be as
expensive as it does in comparison stretches the credibility.

Much of the price hike is in the middle men. 100% markup on accessories
is not uncommon, sometimes more. This covers them for the loss of cash flow
as much of this junk sits on shelves for ages. It can also cost nearly as
much to sell a green marker as to sell an ampilfier. Sometimes you can find
a common industry component (say a high quality RCA plug) in both an electronic
components store and a HiFi shop. The HiFi shop will often be twice the
cost. Its not just rip-off factor (although this does enter into it). They
are just not set up to handle small quantities of odd items.

Really stupid high end stuff is another matter. $250 for a power cord?
Is this real? This isn't price gouging, this is exploitation of the
feeble-minded. P.T. Barnum had things to say about them.

My feeling about many of the pseudo-scientific junk at idiotic prices
(idiot priced speaker cable and $15 green pens) is that it fulfils a void
in the psyches of many unfulfilled audio freaks. Someone may as well get
rich ripping these people off. It is quite symbiotic, as the audio freaks
only feel happy (fleetingly) when they have shelled out 3 months wages
for 20 feet of speaker cable. It's a substitute religion really. Just replace
the sackcloth with golden-ratio-cross-section-solid-silver-time-aligned
speaker cable and the ashes with green markers.

Francis Vaughan

Disclaimer: I only speak for myself.

Steve Kanefsky

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Aug 14, 1990, 11:57:17 AM8/14/90
to
In article <13...@sirius.ucs.adelaide.edu.au> fra...@cs.ua.oz.au writes:
>In article <1990Aug10.1...@techbook.com>, a...@techbook.com (Alan
>Peterman) writes:
>|> Are there really folks who will shell out $15 for a $2 marker that can
>|> be gotten at any local store, and are even being given away free by some
>|> audio shops? Are other "high-end" products similarily overpriced?
>|>
>|> This seems to be somewhat common in audiophile products, the price must be
>|> a "rip-off" to be a truely "high-end" product. Tube traps at $870,
>|> speaker wire at $20 per foot, power cords for $250, interconnects at
>|> hundreds of dollars. While I appreciate good equipment, and good quality,
>|> some of this stuff and their prices are beyond comprehension. Guess some
>|> folks don't care about value - and others love to prey on them.
>

...

>Really stupid high end stuff is another matter. $250 for a power cord?
>Is this real? This isn't price gouging, this is exploitation of the
>feeble-minded. P.T. Barnum had things to say about them.

Yes, this is real. My personal favorite is a power cord upgrade that
Audio Advisor offers for a $300 voltage regulator/spike & surge protector.
(i.e. the upgraded power cord comes *before* the regulation/filtration!)

Here is the blurb in the latest Audio Advisor catalog regarding the ugrade:

"If you own a Tripplite LC-1800, you know how clean power improves your
system. Now you can dramatically improve the sound of your Tripplite--
for an incredibly low price. With a new Phase II power cord from Tara
Labs, your system will sound more musical and more dynamic. You'll hear
smoother highs, a more spacious soundstage, and tighter, deeper bass."

The upgrade costs from $100-220 depending on the length of the cord.

I got a pretty good laugh from this, but I wonder if something like
an isolation transformer could make a difference in the sound, or at least
prevent the ticks and pops through my speakers when I flip a light switch
(a $40 power strip with surge and spike protection and EMI/RFI filtering
doesn't help at all). Stereophile thought that the $1250 power block
made an amazing difference in the sound (but then again they also thought
green marker and Armor-All made a big difference :-) ). I'm not going
to spend $1250, but they said that the biggest improvement was with the
source components and not with power amps, and there are some cheaper models
which aren't meant to handle power amps, but which should work ok on
low-power stuff.


--
Steve Kanefsky
kane...@cs.umn.edu

Mark A. Feit

unread,
Aug 14, 1990, 10:46:04 PM8/14/90
to
In article <1990Aug14....@cs.umn.edu> kane...@cs.umn.edu (Steve Kanefsky) writes:

>|> Are there really folks who will shell out $15 for a $2 marker that can
>|> be gotten at any local store, and are even being given away free by some
>|> audio shops? Are other "high-end" products similarily overpriced?

You'd better believe it! Despite a lot of years of loud music, my
hearing's still intact and my ears still like my 27-year-old tube
receiver better than any of the new solid state gear I keep hearing at
stereo stores. I figure my receiver is worth about $30.00, so
subtract that from the $750 somebody shells out and I have a lot of
change leftover.


"If you own a Tripplite LC-1800, you know how clean power improves your
system. Now you can dramatically improve the sound of your Tripplite--
for an incredibly low price. With a new Phase II power cord from Tara
Labs, your system will sound more musical and more dynamic. You'll hear
smoother highs, a more spacious soundstage, and tighter, deeper bass."
The upgrade costs from $100-220 depending on the length of the cord.

Really? Wow! Maybe if I plug my computer into one of these things,
my computer will operate more like a computer, I'll get smoother
execution, tighter loops, and my RAM will be more dynamic. But
seriously, though... I don't care how many of those things you plug
in in a line, there's still no substitute for a well-filtered,
well-regulated power supply in each component and
sufficiently-shielded cabling between components to keep the noise
out. (Take a hint from us musicians... Guitar cable works wonders on
stereos!)

I got a pretty good laugh from this, but I wonder if something like
an isolation transformer could make a difference in the sound, or at least
prevent the ticks and pops through my speakers when I flip a light switch

Probably not... In it most basic sense, an isolation transformer is
just a 1:1 transformer. Noisy signal in = Noisy signal out. Once
again, the aforementioned well-filtered, well-regulated power supply
will do the trick quite nicely.


- Mark

................................... ...................................
: Mark A. Feit : fe...@cs.odu.edu :
: Old Dominion University CS Dept. : ...!xanth!feit :
: Norfolk, Virginia, U.S.A., Earth : "Where are my socks, anyway?" :
................................... ...................................
"Programming is 10% science, 25% ingenuity, and 65% the art of getting
the ingenuity to work with the science."

--

- Mark

................................... ...................................
: Mark A. Feit : fe...@cs.odu.edu :
: Old Dominion University CS Dept. : ...!xanth!feit :
: Norfolk, Virginia, U.S.A., Earth : "Where are my socks, anyway?" :
................................... ...................................
"Programming is 10% science, 25% ingenuity, and 65% the art of getting
the ingenuity to work with the science."

William Spencer

unread,
Aug 14, 1990, 11:13:44 AM8/14/90
to
in article <11...@alice.UUCP>, j...@alice.UUCP (jj, like it or not) says:
> In article <37...@vrdxhq.verdix.com> bi...@vrdxhq.verdix.com (William Spencer) writes:

>>Essentially, yes. Practically, not so easy. One difference between measuring
>>and hearing is that different sounds are heard as unrelated. The presence of
>>400 Hz at 110 dB doesn't prevent hearing 2222 Hz at 10 dB. The 2222 Hz
>>would only be visible on the highest resolution of oscilloscopes.

> Excuse me, but perhaps you should look into the subject matter before
> you make absolute assertions. Your 2222 Hz signal is about 9.5 critical
> bands away from your 400 Hz signal. Were your loud signal a lower level,
> the 2222Hz signal would be unmasked, although not very audible,
> however, given your absolute level, the spreading function due to
> the cochlear filter separation starts to get much larger,
> in fact, to about 10dB/critical band (or less!). I.e. the JND for your
> 2222Hz signal would be about 95dB below the 400Hz signal,
> or 110-95=15dB, ergo even using a quite conservative analysis,
> your signal would be inaudable.

I thought maybe I was exaggerating a couple dB.

Do these theories take into account detuning? Experience leads me to believe
that 2222 would be a lot easier to hear than 2000 or 2200 which are
harmonically related to 400.

> In practice, of course, the
> distortion from the best existing transducer would easily mask
> your 2222Hz signal.

A pure 400 Hz 110 dB signal would be impossible to produce, yes.

> In other words, you're close, but still substantially wrong.

> These well-known effects can be found in Tobias's book [...]

I appreciate the references but nevertheless find it interesting that
I already more or less knew the answer from experience :-).

I do miss being around good libraries.

> In fact, you even need a smart spectrum
> analyzer. Such exist. I'm sitting next to one.

I'm not. How much dem thangs go fer these days anyhow? Can I borrow it?

> Simple enough to do if
> you study the art instead of making draconian pronouncements.

This draconian pronouncement was good enough to drag some info out
in the open. Ther point I was making remains essentially true.

> A null test is completely meaningless. Since you take the difference
> and present it alone, you have no comprehension if the distortions
> you hear would be masked by the signal.

If there isn't any distortion you don't even have to know if there's any
masking.

> The ear really can't hear very much at all, it's just good
> at a specific set of tasks. Eventually you'll all have to
> accept that.

I accept that the ear follows Murphy's Law: The ear will miss a lot,
but not necessarily every thing you want it to miss.

> Rince *Copyright alice!jj 1990, all rights reserved, except
> Philib *transmission by USENET and like free facilities granted.
> 'A *Said permission is granted only for complete copies that
> Choeil *include this notice. THIS MEANS YOU.

YES SIR!


bill S.

Copyright 1990 WCS. Violators will be strung up by their toenails
and subjected to thrash music, easy listening, or religous music as applicable.
Using genuine DAK equipment, of course.

IMHO,NTOOME

Question authority, it already questions you.

No artist desires to prove anything. Even things that are true can be proved.
--Oscar Wilde

Bob Myers

unread,
Aug 15, 1990, 1:36:19 PM8/15/90
to

It's been mentioned before, but it looks like it bears mentioning again:

Contrary to popular belief, "price" in a free-market system has VERY little
to do with "cost." "Price" ALWAYS equates to "what they're willing to pay
for this product." Just another reason why an informed consumer stands a
better chance of getting the most for his money - especially in the snake-oil
world of audio!

jj, like it or not

unread,
Aug 15, 1990, 4:11:53 PM8/15/90
to

In article <37...@vrdxhq.verdix.com> bi...@vrdxhq.verdix.com (William Spencer) writes:
>in article <11...@alice.UUCP>, j...@alice.UUCP (jj, like it or not) says:

>Do these theories take into account detuning? Experience leads me to believe
>that 2222 would be a lot easier to hear than 2000 or 2200 which are
>harmonically related to 400.

No. They figure absolute detectablity. If the signal were at a harmonic,
it would be substantially *harder* to detect, in fact, for the given
loudness and middle ear, 60dB might be a better estimate for a harmonicly
related signal in the 2K frequency range.

>I do miss being around good libraries.

Hear, hear! So do I.

>I'm not. How much dem thangs go fer these days anyhow? Can I borrow it?

About 20K. 'fraid not, the company owns it.

>If there isn't any distortion you don't even have to know if there's any
>masking.

THAT's the SNR weenie point of view. Now, you may not intend that,
but I do agree that if there exists no difference at all between
the input and output electrical signals (for electronics,
transducers are a wee bit tougher, operating in a transmission
field, and all that) (other than gain), yes, the two should be
exactly the same. This would imply infinite SNR, you realize?
If you say that you can show an amp has a 110dB SNR for all signals,
I'll call it transparent. <please note: ALL signals!>

Now, many old transistor amps had nearly infinite rated SNR, but
didn't sound good. Why? Their choice of the test signal for
SNR was completely bogus. You propose using music. I don't
disagree with that at all, BUT I feel compelled to point
out that many (music) signals with 10dB SNR or worse (with added
noise, NOT phase issues contributing to the bad SNR) SOUND
completely identical to the original. Indeed, the noise
must be added very carefully and creatively indeed, though.

>I accept that the ear follows Murphy's Law: The ear will miss a lot,
>but not necessarily every thing you want it to miss.

That's fer sure.

>YES SIR!
Sorry, quoting of articles is covered by copyright conventions,
and you need not include the whole article in such cases.

>Question authority, it already questions you.

Oh? Don't answer it!!!
--

Norm Strong

unread,
Aug 15, 1990, 12:16:33 PM8/15/90
to
In article <1990Aug8.1...@cs.umn.edu> kane...@cs.umn.edu (Steve Kanefsky) writes:
}In article <1990Aug8.0...@laguna.ccsf.caltech.edu> a...@deimos.caltech.edu writes:
}>In article <66...@sgi.sgi.com>, bol...@ozone.vlsi.sgi.com (Bill Oliver) writes...
}>>In article <37...@altos86.Altos.COM>, t...@altos86.Altos.COM (Ti Kan) writes:
}>>
}>>I've used this product and have done single blind listening
}>>tests with it and have concluded it not only works but it's
}>>AMAZING. Don't talk about things you know nothing about.
}>>
}>
}>Excuse me, but what is a "single blind listening test" ?
}>To do a blind test, you need at least 2 people,
}>one to throw a dice (or other random number generator) and flip
}>a switch, and one to listen and decide if what he hears is A or B.
}
}A single blind listening test is when the subject doesn't know which
}source he or she is listening to.
}
}A double blind test is when neither the subject nor the person performing
}the test knows which is which.

}
}It's possible in a single blind test that the person performing the test
}might subconsciously communicate to the subject which player is which
}(e.g. by facial expressions).

Don't forget the story about Hans, the Wonder Horse. Anyone could ask
Hans to count up to any number, and Hans would stamp his hoof the proper
number of times. It soon became apparent that Hans could also add,
subtract and even extract a square root!

But only if the person asking him could.
--

Norm Strong (str...@tc.fluke.com)
2528 31st S. Seattle WA 98144

Bob Myers

unread,
Aug 16, 1990, 12:45:41 PM8/16/90
to
>To restate my point: Unless _you_ are the owner of the audio system at hand,
>you have no right to dictate what the owner does to make his/her system sound
>the way he/she likes it. If someone wants to spend X amount of dollars on
>equipment that may-or-may-not improve their system, then they have perfect
>right to. What's important is how much they enjoy their music.

No argument here - and no one IS "dictating what the owner does to make
his/her system sound the way he/she likes it," at least as far as I can
see. What do you think, that those of use who are asking for some
justifications for these "tweaks" spend our free time hanging out in front
of the local audio stores, tossing the poor ignorant slobs with their
fists full of money out into the street rather than letting them buy
green markers for their CDs?

Look, all I'm saying is that there is a LOT of snake-oil claims out there,
and a lot of people who are admitting that they don't know enough about
the inner workings of their systems so as to make an intelligent choice.
They're asking for some help/education in making an *informed* decision
as consumers, and frankly, simply saying "try it yourself and see if *you*
like it" doesn't strike me as incredibly helpful. First of all, it would
be an incredibly expensive, time-consuming, and often wasteful proposition
for someone to attempt to try every half-baked idea that comes along, all
on their own - not to mention the very real possibility, as mentioned earlier,
of actually degrading the system or recording permanently. Second, even
having tweak "X" demonstrated by a friend or salescritter, and thinking that
you MIGHT hear a difference, does not in and of itself justify parting with
your hard-earned cash to try it out on your own. Many people would still
like to hear some opinions from people who might know something about the
innards of this equipment, and see what they think about it. The human
hearing system is not without its little psychological quirks, and anyone
who denies this will wind up with a number of highly suspect and often
mutually contradictory opinions - and a flat wallet.

In an effort to try to be helpful, I'm always gonna pipe up and ask for at
least SOME justification for outlandish claims, and give my opinion - for
what it's worth - of said justification. What I (and many others) write
here may be worth exactly what you pay for it; but then, no one's twisting
your arm either way. If you've got money to burn, and want to grab whatever
the latest fad is in tweaks, be my guest; it doesn't make a hill of beans
difference to me one way or another. But tell me - what's the REAL reason
that someone would object to another pointing out the Emperor's state of
undress?


Bob Myers | "Man will occasionally stumble over the truth, but
my...@fc.hp.com | most of the time he will pick himself up and continue."
| - Winston Churchill

Eric Smith

unread,
Aug 16, 1990, 8:03:53 PM8/16/90
to
In article <34...@lulea.telesoft.se> st...@lulea.telesoft.se (Sture Jonsson) writes:

Can your measurement devices say which one in an orchestra plays out of tune,
can it judge which of two performances are more enjoyable to listen to ?

Because things of that nature is all that really matters.

If so, I'd really like to see that (I mean it !).

Listen and enjoy
sture

No, but then I don't want it to do that. What I want is for the output
of the audio system to resemble the input as closely as possible, so *I*
can decide which performance sounds better. I don't generally get control
of the recording side of the process, but I am going to pick equipment
for the playback side that is as transparent as possible. I believe that
the ear is well enough understood that we know what is necessary to
make the path transparent. If green goop on the CD doesn't make a
measurable difference, I seriously doubt that I will hear it, as there
are many things that *DO* make a significant measurable difference that
are *NOT* audible.

I have been the subject of a single-blind test of the green goop, and
I couldn't hear a difference. Of course, I didn't expect to. If
someone else can hear the difference, then they are welcome to use the
green goop. I'll even offer to sell it to them :-)

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