[Dusty Chalk]

Quote:

Originally posted by princeclassic the "all in your head" thing works both ways i'm pretty much a skeptic with most tweaks and most cables... even if a tweak or cable made a noticeable difference, i might not notice it because i'm thinking in my head that i shouldn't be hearing anything... at least it keeps me from spending money though

Excellent! (Starts washing brain...erm...brainwashing self...)

 

[Kali]

Well it has to be said that at least the green-pen treatment has some sort of viable explanation for its (perceived) effects.

But if you want true placebo induced insanity (or gullibility) then try the amber tweak:
http://www.1388.com/html/pavane.html
I really cannot for one second believe the reviews on that page...

 

[JMedeiros]

I use the Auric gel to clean my CDs and rental DVDs...I did use the black pen early on but got lazy. It's a bit messy sometimes and I don't know if the sonic benifits were that evident for me. However...it does make DVDs look and sound noticably better.

John

 

[edstrelow]

I am always interested when someone who doesn't hear an effect calls the person who reports hearing a difference biased. Can't both be accused of bias? Maybe the person who doesn't hear the difference also has bad hearing, limited experience or poorer equipment.

Non-results are suspect in science. In statistical testing in biological and psychological research, someone who finds no difference hasn't found anything, since that does not justify a conclusion about the non-existence of an effect. Generally such research will not be accepted for publishing since a non-result could show bad technical skills, and anyone can do an experiment which doesn't work. However, showing an effect beyond the specified sampling error rate or whatever criterion is set up in various disciplines will allow the reseach to be published.

Of course here, with samples of one, we are not dealing with statistical proof, but the issue of bias applies equally to the sceptic and the believer.

As regards painting discs, I am not sure that green is better than black. The theory is that green will absorb all wavelengths but green and the laser beam is in the red region. However black will absorb everything.

I tried green pens for a while and converted to black while using the Auric product. I also paint out as much of the non-playing surface as I can. The theory being to absorb stray light energy which can give rise to digital errors and the need for "error correction" which is a misnomer for digital guessing as to what the signal should be.

As regards the theory behind why/if cd tweaks may be needed, I have seen reports about the "normal" error rate with cd's which showed dozens if not hundreds of errors per second. These may obviously impact sound. Then there are other claims, including "jitter."

The original proponents of digital sound used claims such as "perfect sound, forever." Obviously this was not true. Do-it-yourself tweaks aside, aren't the designers of CD players "tweaking" them when they put out new designs. I can't imagine anyone arguing that the sound of cd players hasn't been improved over the last 20 years. Ergo, tweaks can work and are needed.

I personally sand edges, paint, cd's weight them and use the Herbies disc stabiliser. Each tweak seems to add something to sound quality and resolution.

While cd's and dvd's are very good they are not a perfect medium and people should explore this area this area of tweaking the disks for themselves. Tweaking is also generally cheaper than buying new equipment.

 

[SunByrne]

Quote:

Originally posted by edstrelow INon-results are suspect in science. In statistical testing in biological and psychological research, someone who finds no difference hasn't found anything, since that does not justify a conclusion about the non-existence of an effect.

Well, yes and no. If you have a great deal of statistical power to detect an effect, and you don't, then you actually can say something intelligent about the null hypothesis.

Also, I wouldn't go so far as to say non-results are "suspect" in science. In fact, I'd say it's more the case that *results* are suspect until they've been reliably replicated. (Cold fusion, anyone?)

Quote:

Generally such research will not be accepted for publishing since a non-result could show bad technical skills, and anyone can do an experiment which doesn't work. However, showing an effect beyond the specified sampling error rate or whatever criterion is set up in various disciplines will allow the reseach to be published.

Well, that's only part of the story. You can beat the statistical criterion and still get papers rejected for poor methodology, bad exposition, or poor theory/argumentation. There's a lot more to it than just showing a low p-value (or whatever).


I think that's what many critics of the green pen thing are reacting to--the notion that the "theory" or explanation behind the green-pen effect is not particularly compelling. Because they do not find this explanation compelling, critics want to see some kind of empirical evidence to the contrary. If that evidence is lacking, the proper "scientific" thing to do is be more conservative, and to go with "no effect."

Quote:

I have seen reports about the "normal" error rate with cd's which showed dozens if not hundreds of errors per second.

I find this highly unlikely, since CD drives in every computer I've ever used read files with a mean rate of zero errors. It would be obvious if it were not so, since a read error will show up as a reversed bit in a file 50% of the time, and I've never seen it happen except with bad media. Would anyone buy a CD drive if it produced files that were not exact copies of the ones on the CD even 2% of the time per large file, much less dozens of times per second? I think not.

I have a hard time believing that even a mid-fi audio CD reading device would be less accurate at reading bits off a disc than a cheapo computer CD drive, but I accept that it's possible, so I'd really like to see these reports--do you have sources for them?

Quote:

I can't imagine anyone arguing that the sound of cd players hasn't been improved over the last 20 years. Ergo, tweaks can work and are needed.

I think one could argue quite reasonably that the improvement has been entirely in the DAC stage, and not in accurately reading the bits off the CD. If that's the case, any tweak aimed at somehow improving the "reading the data off the CD" process is suspect. Note that I'm not saying that is the case, I'm just pointing out that the fact that CD players have improved does *not* logically imply that tweaks like the green pen work.

 

[chych]

Don't forget, CDs have a LOT of error correction on them, 304 bytes per 2352 bytes on each written block is reserved for error checking. That means 85MB of the CD is just for handling errors, and 650MB is available for use. Data CDs have two layers on the disk, one for data and one for error correction, since they have to be more exact than audio CDs (perfect even). (Link).

Thus if the CD player detects a wrong bit, it will use the error checking portions of the disk to interpolate the correct value of the bit. This can actually be noticed when you put in a scratched data CD and transfer speeds go down significantly. With data buffering, you will not notice the slow down on an audio CD player. You would think that each scratch is a lost set of bits but it is read anyway.

Not sure how true it is, but I've heard that you should be able to put a decent sized hole into anywhere on a CD and the CD would work perfectly still. Given the amount of error correction, it can be possible.

So what can the green pen do that CDs can't? Sure, it may marginally reduce the amount of error correction the CDP has to go through, but since the data is not read in real time, it doesn't matter (who cares if the player gets 100 errors/min without the pen and 50 errors/min with the pen when in both cases, 100% of the data is read successfully?)

Anyways, that's my theory, and I expect it (somehow) not to be believed at all by some (unless I'm technically wrong though).

 

[Budgie]

If the effect from Auric Illuminator is all in your head your using it wrong. Your suppose to put it on the cd's. It does make your hair nice and shiney though. Don't ask me why I know that.

 

[edstrelow]

I believe that the words "error correction" are imbued with magical properties for some readers. There is no way CD's can truly correct all errors unless there were infinite storage capacity on discs with the signals being encoded many times so that different versions could be checked with one another. A player can detect a wrong bit, if there is such an egregious error that the system backs up. And then what is the nature of the correction? Extrapolation or interpolation, in otherwords guessing. What about subtle errors which are passed through as being ok. Have enough of such errors and extrapolation on playback and your discs will not sound too good. They'll sound like some kind of music, just not too good. Probably what some people call "digital sound."


There must be some tweaks must be out there which will improve the sound off discs, although maybe its not green pens. Since everything else in technology can be improved, and in audio that means amps, cables, speakers, headphones, etc., it seems most likely that the process of reading bits from discs can also be improved. It would be a truly remarkable state of affairs if we had hit it exactly right, first time around, with CD's and DVD's without any ability to make it better. I doubt that such has ever happened in the history of technology.

 

[chych]

Regardless, if you care to do the measurements, the amount of missed, uncorrectable bits on a 'normal' (undamaged) CD is usually near zero. It does not matter if the system has to resort to "guessing", as you say, because pretty much all of the time it will find the correct value. There is no backing up either, since data is buffered.

And don't tell me you can tell the difference when the CD player screws up on a bit or two, considering the bit rate is around 1200000 bits/second. Look at the article, the guy uses a counter to measure correctable errors; his results are ~900 bits for an 80 second track (on a first gen CDP above all of it), which means 0.000009% of the data was misread but successfully corrected. There is no way any human can hear a 0.000009% deviation in sound if those bits were uncorrected.

 

[Dusty Chalk]

Quote:

Originally posted by edstrelow I am always interested when someone who doesn't hear an effect calls the person who reports hearing a difference biased. Can't both be accused of bias?

Well, yeah, sure, but it's not that black-and-white. It's not a matter of whether or not one is biased and the other is not, it's a matter of how much either is biased, and, in the effort towards the search for some sort of absolute truth, to try to minimize bias.

 

[aeberbach]

Quote:

a truly remarkable state of affairs if we had hit it exactly right

In the eighties no doubt it took years to get CD technology ready for release. If they had cooked it all up on the back of napkin at lunchtime and had it working that afternoon that would be remarkable. A normal R&D process isn't that remarkable.

20 years later there are drives that can read more than 13 times the amount of data stored on a CD. The technology and increased precision flows down to CD. How is it that you can store 700M of data on a CD - filling it entirely - and get it back, bit-perfect, time after time, disc after disc, drive after drive? There's no guessing or interpolation at all, if there was then your file's checksums would fail and you would notice because your disc would be corrupt. Yes, a single bit does matter, for example a GIF will not decode if the compressed data stream is not perfect.(debugging one of those now...)

How is the mechanism that gets data off a CD data disc any different to the one in a CD player? There's at least one mfr (http://www.users.bigpond.net.au/redg.../rg_frame.html) combining CD ROM transport with a DAC. Maybe he's the only one using a perfect transport!

How is music data different to any other data and why would it require a green pen where other data does not? Will a green pen make my data better too? That's the thing about digital, it's either there or it isn't. There is no "better".

 

[edstrelow]

Advocates of digital perfection make me think of the "mad scientist" who was saying things like "but my theories say this shouldn't happen ..." as things were crashing around them.

Perfect is an unwise word to throw around in technology, and I remain unconvinced that we have it even today in reading cds/dvd's.

As far as perfect computer data processing, I sit on a computer all day and am regularly having to restart discs which don't read properly.

To be fair to technology geeks, I spent 5 years myself employed in a university EE department and never heard anyone there claim that anything they did could not be improved on and so I'm not buying the perfection argument in this forum.

It takes a lot of data to make music sound realistic and takes no stretch of imagination to assume that even small problems of data reading could be detectable in sound quality.

Some tweaks help, some don't. And why they work is probably not known either but we have some guesses. The problems with music cd's are subtle and I can't say whether it is missing data, interpolation errors, jitter, or whatever else .

 

[aeberbach]

Quote:

having to restart discs which don't read properly

Huh? CDs? You probably have a bad drive. None of my drives do that. Of course your CDs may be all scratched up from group use at work but mine aren't, and my music CDs are never scratched.

(and if a disc fails to read once it's usually unreadable. What do you mean restart?)

 

[dvw]

The error correction used in audio CD is called reed-soloman coding. It interleaves the data. So any data error caused by scratches etc is spread out and thus can be corrected mathmatically. The coding is invented for basic error free transmission of data. A CD will have defect from manufacturing even it is scratch free (from dust in the air, worn press etc.). The error correction makes the CD usable even with small defect.

However, it is not correctable. If the damage is large enough to wipe out an entire frame. Therefore, cleaning CD in a circular motion often create scratches that are circular and not correctable.

Depends on the position of the bit error, the degradation can be subtle or significant. But the effect is random. The worst case is if the error happens at the MSB, the result is clicking noise. (try real time disc to disc copy at 32x or higher you'll find a lot of these.)

A smoother sound or more detail sound are not the result of lower bit error.

 

[edstrelow]

________________________________________________
Depends on the position of the bit error, the degradation can be subtle or significant. ...A smoother sound or more detail sound are not the result of lower bit error
_______________________________________________
I think you just contradicted yourself.

There appears to be a camp out there who want to believe that somehow cd/dvd discs are perfectly read, contrary to every other technology known to mankind. Even cleaning your laser lens changes sound ona player.

I do not believe that disc reading is perfect, there are error problems including dropped bits,improperly interpolated data, and delay problems such as jitter and probably other problems not even known or understood as yet.

Whether any given tweak actually improves sound, and how, is not generally known or understood, but there are many intelligent listeners who put both their time and money into such things and feel it is worthwhile.

This is no different in principle than in trying different items of equipment or accessories such as cables to see if they sound better, except it is usually cheaper.

For those willing to experiment I recommend www.tweakaudio.com for a good discussion of such issues.