[kelly]

Quote:

Originally posted by disturbed Does anyone know the std. deviation/variance...in failure/error rates between CD Transports across different brands and within a companys own sub brands?

I talked to one of the people who helped engineer the latest Wadia transport and DAC a little while back. He said that when they designed the DAC, several people complained that it wouldn't play their CDs. They didn't understand this since it, of course, worked fine with their transport. Upon further research, they discovered that most transports were not getting close enough to the 44.1kHz needed. They ended up having to widen the tolerances on the DAC so that the DAC could be used with other transports and CD players. Something as small as getting the data off of the disc, we take for granted.

Somehow I think if even the high end transports weren't getting all of the data off the disc, my Plextor drive probably isn't either. My Plextor thinks the original disc and the copy are the same. That doesn't mean they are.

 

[Audio Redneck]

I've been reading through this thread several times, made a few inquiries, and here are some general thoughts:

Is there and audible difference between CDs and CDR's: Sometimes

Why? A cd's platter reflects the laser and the variation in the disc are what create the bits (1s & 0s). On a CDR, the plastic is melted by the burner so that it affects the way light is reflected which creates the 1s & 0s on a CDR. (stick a lable on a Burned CDR, peel it off pulling the platter with it, and you will see what I mean.) The CD is inherantly more "accurate" than the CDR and will require less error correction. *The error correction is the audible difference as it does affect the DAC.*

Are error correction circuits in CD-ROMs and computers better than in audio players? Generally yes.

Why? Because they can be (have to be). These circuits generate noise (RFI, EM) that affect the analog side of an audio system. The more advanced the error correction, the more noise the circuit will generate.

Short version: with a CD/CDR DAC circuit, the harder the error correction scheme has to work, the greater the likelyhood that there can/will be an audible difference.

What are the key factors:
#1: how well does your burner work with the brand(lot) of disks you use. Burners can read a code on the CDR that tells it how to adjust the laser for the best burn.
#2: how modern is you reader(transport) and how well does it read BEFORE the data gets to the error correction circuit.

NOTE1: Personal experiance has shown me that if I burn a CDR at a lower speed, I have a higher success rate in working with older cd players (universal acceptance).

NOTE2: aeberbach makes an interesting point - "If you listen to the audio from each using the SAME mechanism that verified that the copies were identical there is no difference in the sound that comes out." You can only do this if you listen to it from a CD Recorder (computer or audio) WHICH as it happens,its circuits/laser are optimized for reading data off of a CDR. I have personally talked with several people who have started using their CD Recorders (audio component) as the transport for their CD playback system (these are $10K-$25K systems).

COAX vs Optical: The most obvious reason for a difference in sound between these two is that Coax creates an electrical ground loop between the two devices. Optical transmits the same information (ideally) with out creating an electrical connection between the transport (reader) and the DAC (player).

Why would there be a difference made by different optical cables or different coax? Its the same error correction issue in the reader. All audio systems that I've seen are One Way communication - the transport sends, the DAC receives, and if there is an error, its the DAC's problem to deal with it. On a computer system or network, the connection is two way and they constantly check to verify the information sent and resend faulty packets(batches of data).

Thoughts?

 

[dvw]

This topic is covered extensively on the web. check www.cdrfaq.org.

 

[aeberbach]

Worth noting is an Australian manufacturer, Redgum Audio, who make a CD player using a standard CD drive as transport. In fact they call it "D-A converter with CDROM" rather than "CD player".

See the site here:
http://users.bigpond.net.au/redgumaudio/rg_frame.html

One of the guys here posted pictures of his unit, but I don't remember who it was.

 

[Audio Redneck]

If you look for studio/professoinal equipment, you'll find a lot of them doing that with CDROM drives. In the early '90s, NEC SCSI's were popular transports for custom hi-end players.

I wonder what hooking your run-of-the-mill cdrom to an ArtDIO would sound like. Anybody tried it?

 

[dvw]

My experience has been. CD quality makes a bigger difference with low end CD player. High end player seems to have smaller difference (better error correction?)

The APEX DVD uses CDROM, but audio quality is subpar (poor analog section?).

I am considering Extigy or Audiotron right now with my PC. Anyone has any experience with them?

 

[ctenche]

I came across this web page a while ago. It's about whether recording CD-R at different speeds changes the quality fo the audio. It's an interesting read and goes a bit into how the bits are stored on the CD and how error correction is performed. To me, this article shows that a copy of a CD is a 100% copy with no degredation in sound.

http://www.emedialive.com/EM2000/starrett5.html

Just trying to add more wood to the fire