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Burned CDs can sound better than the original?

I recently heard a rumor that some CD burners can actually produce a CD copy that sounds slighlty better than the original. As an Electrical Enginner, I was very skeptical about this claim, so I called some of my reviewer friends, along with some other "well informed" audiophiles, to verify this crazy claim. Guess what, they all said : "With some particilar burners, the copies do sound slightly better!" I did some investigation to why, after all, how can the copy sound better than the original? So far I've heard everything from "burned CD's are easier to read", to "the jitter is reduced during the buring process". Has anyone else experienced this unbeleivable situation? I'm also interested in other possible explanations to how this slight sonic improvement could be happening.
ehider

Showing 3 responses by kthomas

kthomas
911 posts
 
I guess this is the opposite theory to the one that says CDRs sound worse for one of a variety of reasons. I've never been able to get any sort of engineering reasoning as to why either would be the case. Given that it's easy to show that you have an identical copy of the original on the CDR (becuase, obviously, if you don't all bets are off), it's been hypothesized that CDRs sound worse because it's harder to read them reliably.

To give you the best answer to your question that I have, if you copied a CD that wasn't pristine to a CDR that is, you might be able to get an identical copy since the burner can retry reading the CD until it reads it successfully, whereas the CD player can't. Hence, the pristine CDR reads perfectly by the CD player for playback, while the original does not, and therefore sounds slightly better. I would think this wouldn't occur in the vast majority of cases, especially with most audiophiles' well kept CD collections. -Kirk

kthomas
911 posts
 
I can make a provably bit-perfect copy from an XRCD with my computer-based CD copier, and I can make a provably bit-perfect copy of a CDR with same, so I'd be at a loss to explain why an XRCD sounds worse when a mainstream mastering sounds better. I'd also be at a loss to explain why a CDR can't be read better than 95% reliably in a audio CD player when it can be read perfectly in a computer CD drive.

At the physical copying level, assuming computer-based, bit-for-bit copying, the same thing is going on regardless of the source (XRCD, mainstream mastering, or CDR). There's no ADC or DAC going on and it's not clear to me how jitter could be involved in any way. The only potential thing left is something to do with how an audio CD transport reads a CDR vs. a "normal" CD, something that makes it deficient to a computer CD drive. -Kirk

kthomas
911 posts
 
Blues_Man - that's really interesting - I've wanted to hear somebody's experience performing the tests you describe and would be interested in any more detail you might have. A similar test that would be interesting to perform would be somehow analyzing what the transport in a computer CD drive is doing - how many re-reads does it actually have to perform to get the bytes exactly right. It would be interesting to see a histogram of how many times a given track was read - you'd expect a the most at once and a reduced number as the attempts went up. Then it would be interesting to know how many of those read errors could be corrected by the checksums, etc.

I have done comparisons of CDs copied on a computer CD burner and get perfect copies (when it works - occassionally the process fails and spits out the wasted CDR). It's pretty easy to do with the program Audiograbber, available for free. -Kirk

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