[chesebert]

Oh noo..its a crime to deprive one of his enjoyment of Zana..

 

[Dimitris]

A good cd-player can make a big difference if the rest of your components can keep up. However I think that it makes an even bigger difference in a good speaker system.

 

[Freddi]

I'm trying to understand how this works...

A good CD-player doesn't just pick up the signals from the CD and send them to the digital out, but it actually "adds something extra" that sounds good? If not, what is it that makes the difference soundwise?

Feel free to direct me to a site that explains this if you know one...

 

[bordins]

EDIT: duplicate

 

[bordins]

The 30-year-old Red Book Audio standard defines several things for capturing analog sounds into a digital form.

History of CD Technology
Inroduction to Sound Recording (See Compact Disc Topic)
Compact Disc Player

There are several issues of CD technology that need smart engieering. Finally, it is possible.

Let me simplify the story a bit. What we need is to be able to transfer perfect bits of PCM (of sounds) from the studio gone through the CD production facilities to arrive your home (CD player) safely. Several techniques are used to recover possible erroneous bits during the manufacturing process. These also include an immunity to some scratches on the CD surface during the normal use. However, the error correction scheme, that was considered quite good 30 years ago, has some limitation so that you may hear clicks or masked sounds some times.

This implies you can always retrieve perfect bits at your CD player, nothing added to the original bits. Cheap univeral player today (with a large memory buffer and a fast processor) can be as good as $$$$ audio CD transports in the past, in this regard.

The rest is to reproduce the original sounds from those bits, and this is no longer straight forward as you may think, You may know that different DAC chips produce different sounds. The chips have certain "signatures", similar to audio tubes. Components inside the player also affect the sonics. Accuphase CDPs sound warm while Rotel CDPs sound brighter. Lastly, There are all types of noise to be dealth with, like what bigshot mentioned above.

I like an article at tnt-audio, What is Jitter ?. It explains why the same bits can sound different. You can find a lot of information there.

PS CDM vs Player Make & Model List

 

[hciman77]

Quote:

Originally Posted by bordins /img/forum/go_quote.gif The 30-year-old Red Book Audio standard defines several things for capturing analog sounds into a digital form. However, the error correction scheme, that was considered quite good 30 years ago, has some limitation so that you may hear clicks or masked sounds some times.

Even on my $60 DVD player the incidence of uncorrected errors is vanishingly rare, on a bad day I may get 1 or 2 in a 5 hour listening session, although the medium is very error-prone in bit-error rate terms , it has several layers of error correction and only really gross errors are eventually audible.

Quote:

This implies you can always retrieve perfect bits at your CD player, nothing added to the original bits. Cheap univeral player today (with a large memory buffer and a fast processor) can be as good as $$$$ audio CD transports in the past, in this regard.

Give or take the odd part per several million after correction

Quote:

The rest is to reproduce the original sounds from those bits, and this is no longer straight forward as you may think, You may know that different DAC chips produce different sounds. The chips have certain "signatures", similar to audio tubes. Components inside the player also affect the sonics. Accuphase CDPs sound warm while Rotel CDPs sound brighter. Lastly, There are all types of noise to be dealth with, like what bigshot mentioned above.

If a DAC chip has a signature it is basically flawed - the chip has to reconstruct a waveform. The Nyquist-Shannon theorem dictates that it must do this perfectly with a sampling frequency of 2f i.e for 22.05khz you need 441khz sampling. After the analog wave is reconstructed then it can be fouled up any way you choose

Quote:

I like an article at tnt-audio, What is Jitter ?. It explains why the same bits can sound different. You can find a lot of information there. PS CDM vs Player Make & Model List

That article is good in many respects. However the issue of jitter audibility is rather more vexed - while several models of audibility exist and jitter can be shown mathematically to effectively reduce bit-depth it has (so far) been impossible to find real world audible jitter levels in any commercial component - the worst ever found was 4ns (Nishimura 2005) but no properly controlled listening tests have ever shown deterministic jitter to be audible below 20ns (Gannon and Benjamin 1994, AES reprint) . For random jitter the situation is even better with levels below 500ns (Ashihara et al 2005) being inaudible.

 

[bordins]

Thanks, hciman77 for the technical addition.

Quote:

Originally Posted by hciman77 /img/forum/go_quote.gif If a DAC chip has a signature it is basically flawed - the chip has to reconstruct a waveform.

Many have confirmed DAC chip signatures from a DAC that lets you swap DAC chips, like a Zhaolu. I own one and found AD-1852 and CS-4398 produce different sonics of the same music track. The AD-1852 makes music more airy while the CS-4398 makes a female voice more attractive, for example. It is why there are many DAC chips to choose in the market. They must differ, like 12AX7 v.s. 6DJ8 tubes, sound-wise.

 

[CMasten]

Well summarized Bordins! Thanks for the input.

I have about 8 cd players, all the early ones sound pretty much the same, but I just purchased a new Marantz 5001 and its amazing how much better a CD player can sound, and most notable how much better the error corrrection is in this new unit vs the units from say 10-20 years ago, there have definitely been improvements.

 

[Freddi]

Loving the info here! Although my wallet is less pleased

How is the error correction in a DVD player compared to a CD player? Anyone looked into this?

 

[bordins]

Quote:

Originally Posted by Freddi /img/forum/go_quote.gif Loving the info here! Although my wallet is less pleased How is the error correction in a DVD player compared to a CD player? Anyone looked into this?

Are you asking about playing a (Red Book Audio) CD ? Error correction schemes are designed for certain purposes, typically within a set of requirements and limitations of resources for carrying out the correction procedures. To play any audio CD, you need to follow the Red Book standard. A DVD player performs the same error correction as of a CD player when playing an audio CD. In other words, it depends on the standard of the media, not the player.

You may take a look at the related standards.
http://www.mbiweblink.com/BookInfo.html
http://findarticles.com/p/articles/m...v41/ai_9683351

 

[hciman77]

Quote:

Originally Posted by bordins /img/forum/go_quote.gif Thanks, hciman77 for the technical addition. Many have confirmed DAC chip signatures from a DAC that lets you swap DAC chips, like a Zhaolu. I own one and found AD-1852 and CS-4398 produce different sonics of the same music track. The AD-1852 makes music more airy while the CS-4398 makes a female voice more attractive, for example. It is why there are many DAC chips to choose in the market. They must differ, like 12AX7 v.s. 6DJ8 tubes, sound-wise.

Interesting, is this verified by level matched blind tests - even a small level difference in volume changes the perception of sound. Can two DAC chips output different level signals - I dont know, but that would make a difference.

Can you explain why two DAC chips that both perfectly reconstruct the same analog waveform can sound different - can you provide some performance specs for the DAC chips you mention - it would be educational for me.

EDIT: I looked up the specs for both the chips you mentioned - mostly tough going as both spec sheets have a lot of EE stuff I dont really understand too well. From what I can tell the AD1852 is slightly better in the usual tech stats THD and so on but both are well pretty exemplary in real world terms. It is hard to see where any audible differences would come from. The only thing I can think is that the two chips are not electrically identical and if you swap them in the same circuit there would be some slight differences in the properties of the circuit, I am still a bit skeptial this would lead to the sort of differences you mention but who knows ....

I can see how the analog sections could make a big difference but I am puzzled that the reconstruction process can be so different. As long as two DAC chips are linear to 16 bits the analog signal ought to be the same.

Can you dig out some tech stuff, this is intriguing.

Cheers

 

[bordins]

Quote:

Originally Posted by hciman77 /img/forum/go_quote.gif Can you explain why two DAC chips that both perfectly reconstruct the same analog waveform can sound different. As long as two DAC chips are linear to 16 bits the analog signal ought to be the same.

Your assumption could be wrong. It is because the waveforms of different DAC chips are not the same.

They would look the same on a large-scale measurement, like on an oscilloscope or a THD meter. But psychoacoustic studies have shown that human hearing system is so complex, and it is *very* sensitive. This is why people can be very picky about quality of music CDs. Your measurement instrument of choice should be human ears which can detect any subtle sonic differences.

Quote:

Originally Posted by hciman77 /img/forum/go_quote.gif From what I can tell the AD1852 is slightly better in the usual tech stats THD and so on but both are well pretty exemplary in real world terms. It is hard to see where any audible differences would come from. Cheers

THD tells you about the difference between the input and the output, seeing the DAC chip as a black box, surely the lower the better. I am not an expert in this field to be able to explain what components in the chip make audible differences. I came across a interesting article on human perception about musicality.

Towards a Neural Basis of Music Perception

BTW, I remember a documentary program taking to see inside a tomato sauce factory in Pittsburgh. Even scientists know exactly how to measure all ingredients and to how to cook ketcup right. They still need a human tounge to tell whether to add more sugar, vinegar, salt, etc. Otherwise, the customers (KFC, McDonald) will reject the sauce. You can get a high-precision pH meter or a million-dollar gas chromatograpy machine to measure different brands of ketcup. Even the fancy graphs look exactly the same, but which ketcup would you prefer ?

 

[Fitz]

Quote:

Originally Posted by bordins /img/forum/go_quote.gif Your assumption could be wrong. It is because the waveforms of different DAC chips are not the same. They would look the same on a large-scale measurement, like on an oscilloscope or a THD meter. But psychoacoustic studies have shown that human hearing system is so complex, and it is *very* sensitive. This is why people can be very picky about quality of music CDs. Your measurement instrument of choice should be human ears which can detect any subtle sonic differences.

Which studies specifically? I'd like to learn more about this.

 

[bordins]

Quote:

Originally Posted by Fitz /img/forum/go_quote.gif Which studies specifically? I'd like to learn more about this.

You can find some of them in the links below.
Psychoacoustics and Music - Introductory Definitions
Recent research in psychoacoutic music & sound
JSTOR: The Acoustical Foundations of Music
Journal of Music Theory, Vol. 13, No. 1 (Spring, 1969), pp. 148-151
The psychology of music. A book chapter (PDF)
Music, Cognition, and Computerized Sound: An Introduction to Psychoacoustics.
Perry R. Cook (Editor). MIT Press, 1999.
Sound, synthesis and audio reproduction.
The Acoustics and Psychoacoustics of the guitar.
Howard Wright's PhD Thesis.
Acoustics and Psychoacoustics, Third Edition, 2006.
High Fidelity Multichannel Audio Coding A book review at Analog Devices
Dai Tracy Yang, Chris Kyriakakis, and C. Jay Kuo, Hindawi Publishing Corp., 2004,
ISBN 977-5945-08-9
Audio and Hi-Fi Handbook (PDF)
Evaluation of Quality for Audio Encoding at Low Bit Rates
http://www.aes.org/e-lib/browse.cfm?elib=4996
Perceptual Encoding System. (A psychoacoustic rational for MP3 encoding)

A historical debate: DSD v.s. PCM
Bitstream versus PCM debate for high-density compact disc
http://www.stereophile.com/features/374/index1.html

Physical v.s. Psychological attributes of Sounds.
Psychophysiology and psychoacoustics of music: Perception of complex sound in normal subjects and psychiatric patients

An interesting article about a DAC mod, "All DACs are EQUAL?".
http://www.1388.com/doctor/jonopinio...001/index.html

EDIT: Fitz. I didn't see your post below. I am not aware of the exact study you asked but will try to find out later. However, what I meant was people may think waveforms out of two DAC chips are the same but they actually are not at the level of human's "waveforms".

 

[Fitz]

I'm not going to sift through all of that. Which ones showed that waveforms that measured 100% identical were perceived differently by the study participants? Those're the ones I want to read.