Why CD players will never be dead

well steve, if you think my cd player will sound inferior to your transport and some dac, put your money where your mouth is.

as you realize there is no accounting for taste.

you cannot make a definitive statement that one component sounds better than another, because the null hypothesis will be rejected if one person prefers a cd player.

"To Steve (Audioengr) or anyone else inclined to explain...How is it possible for a copy of a CD played from a computer hard drive to sound better than the original CD?"

Okay, simple. The jitter that is caused by the pits in the CD and their unevenness makes it worse than playing back using sync USB interface or networked interface.

This is easy to test. First rip a CD track using either XLD on Mac or dbpoweramp on PC with Accurate-Rip enabled. Then rewrite a CD onto 2 different CDROM blanks, one Mitsui Gold audio master and the other TDK or equivalent. Then play all three disks on the CD player. If any of them sounds different, then there you have the proof. If you argue that the rip is different, then listen for differences in the 2 CDROMS. If you hear any difference, then ther is your proof. The CD player jitter is affected by the pits on the disk.

Steve N.
Empirical Audio

"the transport read is not and is reliant on error correction"

That is true, however there is actually very little error correction happening, if any, with a clean CD disk. The difference in audio quality is a result of jitter from the CD player, caused by the pits in the CD or the jitter from the clock in the player or both.

Steve N.
Empirical Audio

Mr. Tennnis - I will put my product where my mouth is. You put the money down. A bet requires both of us to have skin in the game.

BTW, did you read the Dec. Stereophile?

Steve N.
Empirical Audio

11-27-11: Ghosthouse
How is it possible for a copy of a CD played from a computer hard drive to sound better than the original CD?

Some good responses have been provided above. The following excerpts from this thread provide further elaboration on some of the things that have been touched upon:

07-19-11: Shadorne
If a disc wobbles while it spins then this may cause cyclical adjustments to the pick up laser servo and these repetitive draws on power may induce variations in the clock through the power supply.

07-20-11: Kirkus
CD players, transports, and DACs are a menagerie of true mixed-signal design problems, and there are a lot of different noises sources living in close proximity with suceptible circuit nodes. One oft-overlooked source is crosstalk from the disc servomechanism into other parts of the machine . . . analog circuitry, S/PDIF transmitters, PLL clock, etc., which can be dependent on the condition of the disc.... One would be suprised at some of the nasty things that sometimes come up out of the noise floor when the focus and tracking servos suddenly have to work really hard to read the disc.

The following excerpt from this paper by Steve reinforces the point about jitter that he stated above:

3. Jitter from the pits on a CD:
These are the pits in the CD media that represent the recorded data. Variation in the spacing of these pits result in jitter when reading the data. Commercially CD's created from a glass-master generally have more variation in the locations of the pits than a CD-R written at 1X speed on a good CD-R writer. Even though most modern CD players have buffering of the data to create some tolerance to this jitter, there is usually a PLL (Phase-locked-loop) involved, which is still somewhat susceptible to jitter. To determine if your player is susceptible, it is a simple experiment to re-write or "clone" a CD and then listen for playback differences from the commercial version. For newer players that completely buffer the data at high-speed from a CDROM reader to a memory buffer, this jitter is not an issue.

Of course, having the digital source and the dac in separate components creates other ways in which jitter can be introduced, especially if synchronous interfaces such as S/PDIF, AES/EBU, or adaptive USB (as opposed to asynchronous USB) are used. And as usual the quality of a given implementation, or lack thereof, can be a more significant factor than the approach that is chosen.

BTW, not to belabor an issue of semantics, but what is being referred to as "error correction" is more properly called "error interpolation" or "error concealment." "Error correction," which as I understand it occurs many times during the reading of a typical cd, is by definition bit perfect, i.e., the error is corrected! See this Wikipedia writeup, and this one.

Regards,
-- Al