[Glassman]

please verify what data your CD player actually reads by recording it's s/pdif output using soundcard, if they all match and you still hear 'clear' difference, there's something worth digging into and investigating..

 

[Jahn]

Quote:

Originally Posted by WmAx ONe of the interesting things is that you can not 'will' or 'control' your bias to an absolute. It's a subconscious factor. -Chris

Hmm, so it might have been my concious thought that the gold disc should be better, but subconciously i desired the rip to better it? Eh, who knows how my head works.

And Glassman, I must admit I'm a computer luddite when it comes to the testing stuff you guys are talking about. Other than my standalone source, my only other transport of semi-worth is my computer, and I don't have much in my computer to really get down into the technical nitty gritty of it - and hello, is that a SBLive! in there?

I'll just rely on the kindness of strangers and continue to leech off of this useful discussion, and meanwhile trust in my ears and my subconcious!

 

[Regus]

Now while I am no engineer or particularily well versed in these matters I do know a little and to me eyeteeth's explanation sounds like this is
what happens:

The copied cd is of poorer quality and the CDP fails to read some of the data.

Instead of producing a dreadfull sound the CDP interpolates the the missing samples based on the surronding samples. A good solution that allows playback of scracthed cd's with almost no noticable effect (that is as long as the scratches are few and far between)

Asuming that there is a fairly large amount of failing data this would no doubt result in a reduction of short peaks.

Effectively blurring the music.

This is not very noticable where the difference between a sample and the sourounding samples is small, but where there are steep changes (such as with S and T sounds) the interpolation algortihm will arrive at a result significantly different from the correct one. And thus create an audible difference.

Now as I said my knowledge in these areas is limited and i have no clue whether CDPs even do this sort of interpolation, but the theory fits the perception of the results...

The experiment I would suggest performed is this: try to rip the copied CDs with EAC and compare them to the rip of the original... and even more interesting would be trying burst mode on both the orriginal and the copy and compare both of these to the orriginal ripped in secure mode...

If my thesis is correct and the CD-ROM drives are not vastly superior to those in the CDPs the result will be this:
RipA being Secure Mode of orriginal
RipB being Burst Mode of orriginal
RipC being Burst Mode of copy

RipB will be identical to or only slightly different from RipA

RipC will different from both RipA and RipB and more different from RipA than RipB is from RipA.

or more consicely put

diff(RipA, RipC) > diff(RipA, RipB)

Now the secure mode rip of the copy might be identical to RipA but it is doubtful that the CDP goes through as much trouble as EAC to get the correct result from the CD.


Now onto the really thin ice:

If I understand the difference between tube amps and solid state amps, then this is not so much different form the difference between these two, I would therefore suggest that those that like the copies better than the originals would most likely also prefer tubes to solid states...

 

[Glassman]

when done properly, copy is bit perfect to original, period.. and from my own as well as many others's measurements of player's S/PDIF output, common CD players output data that match EAC rip.. draw your own conclusions.. I'd like to see S/PDIF out vs. EAC rip comparisons for those CDs that 'sound different than original'..

 

[Regus]

Quote:

Originally Posted by Glassman when done properly, copy is bit perfect to original, period.. and from my own as well as many others's measurements of player's S/PDIF output, common CD players output data that match EAC rip.. draw your own conclusions.. I'd like to see S/PDIF out vs. EAC rip comparisons for those CDs that 'sound different than original'..

I fully agree, I do however doubt it is done properly... The EAC rip is no doubt bit perfect but the copies could very easily be of poor quality (or it could be that the readers in the CDPs are poorly equiped to read the differnt kinds of dye and reflective materials...)

 

[antonik]

Quote:

Originally Posted by Glassman when done properly, copy is bit perfect to original, period.. and from my own as well as many others's measurements of player's S/PDIF output, common CD players output data that match EAC rip.. draw your own conclusions.. I'd like to see S/PDIF out vs. EAC rip comparisons for those CDs that 'sound different than original'..

I am copying my message from another thread here as it is on topic and is more relevant in this thread. I hope it is OK - if not, I hope that one of the moderators will explain to me the gravity of my error

. It is only a brief explanation of what I've found at the time. I've used a control of the datastream through S/PDIF output, so I was sure that there was no actual data errors/differences between "original" discs and CDR copies.
_________________________

I did research this problem quite seriously few years back in a process of Creek CD53 design. Yes, there could be a difference in the sound between an original "silver" CD and a bit-perfect copy of it. This difference could be heard even on a medium quality equipment. Moreover, usually it is easier to spot the difference on such equipment, thought I didn't actually try to do it on a boombox . I found that there are ways to minimise (or more precisely illiminate for most purposes) this difference. Main source of such difference is not in a digital domain at all, but in a purely analogue domain. Put it simply, the servo system of the player, especially the laser tracking part of it, is a single most powerful source of an audio frequency electrical noise in the player, mostly into the power supply. There is a difference between how a pressed disk or a burned disk are affecting the servo - the spectrum of the interference does change somewhat and this is what in my experience does change the sound. There are several different ways how this noise could influence the sound - from direct coupling to the audio output of the player, to a different jitter components in the DAC and on the SPDIF output.

Alex

 

[Jahn]

That post is indeed on point, thanks for the insight!

 

[Glassman]

Quote:

Originally Posted by antonik I did research this problem quite seriously few years back in a process of Creek CD53 design. Yes, there could be a difference in the sound between an original "silver" CD and a bit-perfect copy of it. This difference could be heard even on a medium quality equipment. Moreover, usually it is easier to spot the difference on such equipment, thought I didn't actually try to do it on a boombox . I found that there are ways to minimise (or more precisely illiminate for most purposes) this difference. Main source of such difference is not in a digital domain at all, but in a purely analogue domain. Put it simply, the servo system of the player, especially the laser tracking part of it, is a single most powerful source of an audio frequency electrical noise in the player, mostly into the power supply. There is a difference between how a pressed disk or a burned disk are affecting the servo - the spectrum of the interference does change somewhat and this is what in my experience does change the sound. There are several different ways how this noise could influence the sound - from direct coupling to the audio output of the player, to a different jitter components in the DAC and on the SPDIF output. Alex

thanks much for your entry, now see my first post in this thread, it's more or less what I supposed, the difference is due to the increased servo activity that is affecting clock lines and supply and as you proposed even RF modulation.. that explains it all and I have no offence to such explanation.. btw. when I tried explaining such thing to some PhD student on Czech Technical University, Department of Radioelectronics, he was laughing at me and thinking what a fool I am

btw. it's always nice to see audio engineers here

 

[antonik]

Quote:

Originally Posted by Glassman it's always nice to see audio engineers here

It is nice to be here... . Great place!

Alex

 

[Scorpio(DDMF)]

So what's the moral of the story?

"CD copy - more smooth sounding than original (because of rolloff in the extremes)?"

Cheers