Bits Are Bits, Right?

mkgus
Last night I copied one of my favorite CDs to a black CD-R and the difference in sound quality between the 2 discs was quite apparent. The treble was much more laid back and “tamed.” I could hear micro-details better. It’s too early to conclude which version is better as they both have their pros and cons. I’m interested in the “why.” Does one disc have more read errors than the other? If not, then I conclude that the way the data (the exact same data, that is) is arranged on the disc matters. The precision of the pit spacing, the width and depth of the pits, and the material of construction of the CDs may play a role. If it’s all the same data and the read errors are minimal, then what is happening before the buffer is having effect on the sound.

>>>>>There are a number of possibilities. One is that the copy routine was copy til perfect. Another is that the laser reads black CD-Rs better than standard silver CDs. It could be there’s less laser light scattering in the black CD-Rs. Just as 24 it Gold CDs have higher reflectivity than silver CDs and usually sound superior. One reason SHM Super High-Performance Material CDs from Japan generally sound superior is the clear layer of the SHM CD is more transparent to the laser than plain old polycarbonate which is only about 91% transparent. Less light scattering. Better optical signal to noise. It’s possible the clear SHM material is stiffer than ordinary polycarbonate and that the CDs are more perfectly round. Another more far out possibility is that copies just sound better, period. Copy an LP to tape, copy a CD to CD-R, copy a CD to tape. No one knows why.

The spacing between pits and lands varies, they represent a series of “words” of variable but specific meaning, the length of pits and lands themselves is also variable. the details are specified in the REDBOOK standard. The geometries involved with depth of pits is also specified in the REDBOOK. The system won’t work if the geometries are not absolutely correct as the laser light beam cancels itself out by wave interference when it strikes a pit. That’s why there is no return light signal for pits, only for lands.

@mkgus,

I hear noticeable differences between the sound quality when streaming through my iPhone over Bluetooth vs wired connection. The wired connection in my car always sounds more dynamic, less congested and smooth.

I have no experience with CD-R, I am either listening to Qobuz streaming or original CD / SACD’s through my CD and SACD players. To my ears, some of my favorite CD’s sounds better through my CD Player (with tube output stage) vs digital copy of same CD stored on my streamer internal hard drive.

To me, it’s all come down to the implementation. The devil is in the details.

@mkgus,

Bits are bits. Some DACs like MSB and PSAudio Directstream support bitperfect test files that you can stream from your source.  When the DAC detects the file contents, it lights up 'BitPerfect' ...which tells you the path from your source to the DAC is not disturbing the bits.  CD players are bitperfect sources - those bits from the CD get to the DAC with 100% fidelity.  
Then why do some CD's sound different?  Even pressed vs ripped CD's of the same album? Its because the semiconductor chip in the CD player is a clocked digital device that has to decode the error-correction of the physical media. So even though all the CDs contain the same music data, the physical substrate varies and reliability of the encoding on the disk varies and the chip works differently to extract the correct bits.  Hence the bits always are decoded correctly but the process of the chip doing so produces disturbances in the EM field generated ...and this (remarkably) affects the DACs analog electronics (stability of reference voltages).  This effect is true with a galvanic coax connection but even with a isolating Toslink, the EM field leaves the CD enclosure to travel meters to the DAC.
We're all dumbfounded by this because its seems impossible that such miniscule issues should be audible ...but they are.

Mkgus 2-21-2020
If it’s all the same data and the read errors are minimal, then what is happening before the buffer is having effect on the sound.

As I see it the reason is that what is happening before the buffer, which is dependent on the physical characteristics of the particular disc, is affecting circuitry that is after the buffer.  That is the basic point Kirkus was making in his 2011 post that I quoted above.  Those effects are not occurring via what he refers to as the "forward signal path," meaning the intended signal path that we tend to think of, but rather via coupling of noise via unintended pathways.  Those would potentially include grounds, power supplies, stray capacitances, or even the air.  Such effects will of course vary depending on the design of the specific component.  

Regards,
-- Al
 

Okay, which one of you submitted this question to Paul? The timing is eerie. 
CD or High Resolution Streaming?https://www.psaudio.com/askpaul/cd-or-high-resolution-streaming/