Re: [ARSCLIST] "Record Club" CD's redux

[Bob Olhsson <olh@xxxxxxxxxxxxx>]

-----Original Message-----
>From Tom Fine: "...The jitter issue raises a couple of questions:

1. would this trigger more error-correction in the playback system and hence
the perceived 
"different" sound qualities?

2. if one grabbed the same cut from the BMG and original-issue CD's with
Exact Audio Copy, assuming 
EAC reported about the same quality percent from the grabs, would you have
identical-sounding files 
on your hard drive?..."


It's important to remember that while digital audio offers the potential of
near perfection, implementation, especially in analog clocking circuitry,
RFI suppression and grounding determines how close we actually approach that
potential in real world devices. Copying a CD indeed allows comparing apples
to apples.


I can offer a bit of an update about some of what we've learned since Bob
wrote his article.

First off, it turns out the generation of SPDIF/AES/EBU chips that were used
at that time were poorly designed and generated massive levels of clock
jitter. Changes in all manner of factors could audibly change the spectrum
of the jitter. According to Goran Finnberg, swapping these chips out for the
latest generation can make lots of older digital gear perform the way that
was originally intended, near perfect. Today the problems described have,
thankfully, ceased to be a problem.

An engineer at Phillips also revealed that most CD players used a servo
motor amplifier and master crystal that were located on the same chip. The
more servo activity, the more that chip heats up and the faster the audio
plays! Things like silkscreen color, changes in the mass of a CD and pit
jitter could result in CDs running at very slightly different speeds. David
Smith told me that Sony had finally traced the jitter problems they had been
jumping through hoops to solve to a particular laser beam recorder although
he wasn't free to explain what was wrong with it.

Where there is smoke, there usually has turned out to be fire only it
generally isn't caused by things folks in the audiophile press typically
speculate about. Apparently it's better to cite mysticism than to call out
one's advertisers for poor engineering design.


Bob Olhsson Audio Mastery, Nashville TN
Mastering, Audio for Picture, Mix Evaluation and Quality Control
Over 40 years making people sound better than they ever imagined!
615.385.8051 http://www.hyperback.com    http://thewombforums.com