Some people say that directly copied Audio CDs via Nero, for instance, don't sound as good as the original ones

is that true?

Taken from this page.

Audio Master Quality Enhancement System This exclusive new Yamaha feature is designed to guarantee the best possible audio recording quality on conventional 74 or 80-minute CD-R disc. When Audio Master Recording Mode is enabled, the system widens the lands and the pits, significantly reducing jitter created during CD-R recording, improving audio and music recording quality to a level rivaling professionally prepared music CDs.

but then again.. it's Yamaha, and it's info from their own page
If you're picky use EAC.
but normally you shouldn't be able to hear any difference

There were numerous threads on CDR audio quality vs pressed CD audio quality in the past. First reaction would be digitally identical data should give identical sound, but in reality it seems a little more complicated.
Possible differences could be caused by jitter when playing recorded CDs.
Use the search function on this forum to read more..
Another factor could be that audio quality is degraded in the various error detection/correction layers when reading the data. You could read this article on CDRInfo to learn how tricky this process could be.

This HA thread could give some more hints.

edit: Typo & added some links

Yes hanky is corrrect.
You have to find some info on what jitter is to understand this issue.

As was said at an old post (can't find it with the search function!), jitter in cd players may happen just on very bad quality players.

That's because the only relevant jitter is the one that goes thru the DAC, and in cd players the data read is buffered, processed (error correction) and sent to the DAC at a fixed clock rate.

So any jitter read from the media is eliminated before arriving the DAC.

Computers do that, but CD-players? Do most of them buffer data before sending it to the dac?
I'm asking because in an "audiophile" magazine there was an article about the revolutionary RAM-technology. One high-end manufacturer said, they didn't need it as they have their "Belt-drive" that "evidently creates less jitter".

Hifi CD players have a small data buffer. When this buffer runs low, the CD speed is increased to fill the buffer. When the buffer goes full, the CD speed is reduced to prvent a buffer overrun. Data from the buffer is clocked(with a crystal oscilator) to the DAC. The only jitter introduced in this state is the quality of the crystal oscilator.

CD players do that, but computers?

Think about how the (audio) data is written on a CD, Sector Interleaving, Salomon Reed coding (for error correction). It's not realy a "stream", it has to be "decoded" first.

So it can't be jitter. There could be a difference in the error correction, although tests have shown that burned CD's have much lower BLER (error rate) than most pressed ones. Also recent CD-players read CD-R (and nowadays CD-RW) without problems.

Most likely it would be something introduced in the ripping proces (CD-ROM drive not good at DAE or normalise to 98% ( OMG))
--
Ge Someone

I tried to post this yesterday, but my DNS server is not updated and I couln't reach the new hydrogenaudio actual ip.

Well, here it goes:



Well, ALL of them do that.

That's because the data witten at the cd is sort of "scrambled" at the bit level and encoded, including also redundant data, subcode info, etc, and must pass through a relatively complex process before sent to the DAC.

The data from just one sample is scrambled together with the data from close samples. This is done to make easier the process of error detection and correction. In order to recover properly each sample stored at the cd, all this scrambled data must be read and fed into a FIFO buffer. Once a block of data is stored on the buffer, it is error checked, error corrected, de-scrambled, and, finally sent to the DAC. All this process is done at a fixed rate, imposed from the DAC internal clock. The rotating speed of the transport is also controlled with reference to this clock, so that the buffers don't over/underrun.

So, the physical jiiter at the cd layer is irrelevant, because the system reclocks all the data read using its internal fixed clock before sending it to the DAC.

By the way, don't trust high-end magazines, and even less high-end manufacturers advertising. BTW, ones live from each other, so, what can you expect??

Many of them believe in the great sound of things such as upsampling devices, esoterical audio cables, DACs without reconstruction filters, and in some cases even weirder things. Also, they don't even what to hear anything about DBT's :'(

That's what I was thinking, I mean, it's the only reasonable way to buffer information somewhere between the physical reading process and sending it to the DAC (due to the error-correction codes on the CD).

But I was stumped for a moment by this article. Now I still don't know why I should pay >10000€ for a belt-driven reader to reduce jitter.


Hehe.. True, but they are still funny to read sometimes.

A big thread about the sound of CDRs : http://www.diyaudio.com/forums/showthread....=&threadid=6545

Some interesting posts, but not much.

It seems the background behind the CDR sound theory is deeper than I thought.

Some links :

About Jitter (with further links) http://www.geocities.com/jonrisch/jitter.htm

A little story about manufacturing CDs : http://www.rogernichols.com/EQ/EQ_2000_02.html

The system on the Yamaha drive seems to be a good one - CDs that have been burned with that system and then tested for error rates have shown less data errors than most other CD burners.

Very interesting together with the F1 are the quality changes listed here:

http://www.cdrinfo.com/Sections/Articles/S...D%2DRW&index=10

Does anybody know what brands are from Mitsubishi Chemicals? They seem to be in love with the F1

Wombat

Verbatim DataLifePlus (many board members' favourite CD-R ) are made by Mitsubishi.