The title is:"There's No Such Thing As Digital..."

07-24-13: Zd542
I'm not sure I get that. I hear comments all the time stating computer audio sounds better than a CD player. Why? I don't understand how ripping a CD and playing the audio file on a computer would sound better than just using a CD player.

Playing a CD is not the best way to source a digital data stream intended for music. Any timing errors expressed as inconsistent spaces between the CD's pits enters the digital/analog converter and distorts the shape of the resulting analog waveform compared to the one originally recorded and digitized. Mass market CDs have jitter just from the stamping of the pits into the substrate. Then the disk is played back, usually on a not-very-rigid CD transport, often made of lots of flexible plastic. As the data stream is transmitted to the D/A converter, more jitter can creep in from reading and re-reading data, from varying impedances, etc. Ripping a CD to a computer hard drive eliminates these timing errors. New timing errors can occur from the hard disk read, especially if the music file is fragmented among several blocks scattered around the disk, but if the data is buffered in RAM all timing errors are basically reset to zero.

Compared to most CD players, a home computer can be a very powerful playback system, with a CPU whose cycles are measured in Gigaseconds, several Gigabytes of RAM that can be co-opted to buffer the data stream and stabilize it, thus removing jitter that might have accrued along the way. Finally the computer-sourced music files are sent to the DAC via an asynchronous USB link. USB, unlike S/PDIF, is a bi-directional link. It doesn't need the clock signal that comes down the datastream pike; it can generate its own freshly when it enters the D/A converter, making for a jitter-free conversion. This is a significantly different way to convert a digital music stream from the typical CD player.

In fact, for a very long time I've wondered why high end audio companies kept
resorting to expensive Herculean methods to lower jitter--diecast metal transports, thick faceplates, expensive vibration-reducing footers and damping materials, etc., when all they really needed to do was put a few megabytes of RAM in there to buffer the data stream and re-clock it. That's what the Genesis Digital TIme Lens (DTL) of the mid-'90s did--for $1195.

Founder Arnie Nudell used to cut demo CD-Rs to show off his speakers by playing the CD's data stream through his DTL before burning the CD. The resulting CD sounded better than the original and made his speakers sound better at the shows.

There is a wide variety of music playback computer software out there, and most of it is way cheaper than a CD player. I use Audirvana Plus on my MacBook Pro. With it I can configure Audirvana to freeze email and automatic backups so the CPU is never interrupted from playing music. I can reserve up to 8 GB of RAM to buffer the music files before decoding. This is especially helpful if you keep your music files on a USB hard drive. I also configure it to upconvert Redbook CD files to 88.2Khz and 48Khz files to 96Khz. If I ever get a 192Khz capable DAC I'll upconvert Redbook files to 176.4 Khz and 48 and 96Khz to 192Khz.

All these things can make the original digital file sound better on conversion, and most of these things are not available on CD players under several thousand dollars.

The science mafia over at Head Fi had a field day with this. They love to shred any idea that claims subjective imprvement. This article smacks of USB cable wankery in their opinion. I offered it as some explanation as to why a cable could make a difference in sound.

Stopped reading after the first answer in this Q&A therapy for trusty ones. I don't want to use word "gullible"... This industry is truly something. They view us as boobs. OMG, Ones and Zeroes and the problem of voltage.

Hello Johnnyb53. Thanks for the overview.

I didn't think there was any such thing as 100% jitter free? I thought all timing sources had jitter? Have you also overlooked the fact that some CDP's even reasonably priced ones, use high speed drives and buffer into memory for CD playback?

Computers were designed for word processing and have some of their own challenges likes noisy fans, cheap and very nasty RFI / EMI emitting power supplies, CPU interruptions etc.

Finally, jitter is a timing error. At what point does that become audible? Can our ears really detect say 400 pico seconds of jitter? If not then even a basic CDP is acceptable.

Kiwi, I suppose if I want to clutter my post with un-ending qualifiers, I should have said "drastically reduces jitter" instead of "eliminates." Still, if you take the time to check the spectrum analyses of several Stereophile test reports, you'll see that the asynchronous USB DACs have very low jitter that is barely visible in the graphs.

Second, I didn't know that reasonably priced CD players were speed-reading and buffering the data first. Can you name some? Since the audio press is making a big deal about the just-released $6,000 Parasound CDP featuring this read-and-buffer feature, it didn't seem that it had gone mainstream yet.

Third, your summary of what computers are for is narrow and dismissive. I landed in Silicon Valley in 1980 and worked in high tech computers from then until the end of 2006. Word processing applications were a relative latecomer. Also, when the industry switched to graphics-based interface and displays, the desktop-publishing apps were some of the most CPU-intensive applications available, right up there with finite element analysis and solids modeling.

Along with that, my MacBook Pro has a 2 Ghz processor and 8 GB RAM, far more processing power than a typical--or even expensive--CD player or DAC. It has an aluminum housing (well-shielded), and no fan. AS I MENTIONED BEFORE, the Audirvana software (and several other packages) can be configured to turn off all CPU interruptions. It's called "hog mode." Look it up.

Once a music data file is buffered in RAM, the clock is reset. It doesn't matter how much jitter was in the stream before, for the moment, bits is just bits. At that point when it enters a new stream to the DAC, it's coming with a fresh and reset clock and is not subject to additional jitter coming from reading a wobbling plastic disc.

Finally, it was Ed Meitner of Museatex who discovered and published about jitter over 20 years ago. At that time listening tests revealed that jitter became audible around 200 ps. This presented a challenge to the industry as the most popular receiving chip at the time was only accurate to 20 ns.

And anyway, at some point arguing the numbers becomes a moot point. With standard CDPs not only did I find myself not enjoying the music, I even noticed that the family got more irritable when the music was playing. With my current computer setup, I can actually enjoy digitally-sourced music. I still play a lot of records and go to live concerts for reference, but the computer-based (especially high-res) digital playback is closing the gap.