Error Correction during CD replay // Super Black Hole from Herbie's Audio Lab


I tried my best but just cannot comprehend this statement from Herbie's page:  "Error correction in audio CD discs is not perfect; it is algorithm-based "guessing," not binary like in data CDs"
Why is that? and does this apply to, say, McIntosh players spinning discs at double speeds? What about CDs ripped onto HDD?
Any info or links very much appreciated.

For months now I am struggling with my Wadia 781i trying to understand why it refuses to play a few CDs from my collection. Narrowed down, at least some, to pressing defects: some CDs are seriously eccentric, when played on tiny Discmans such CDs make them jump like an unbalanced centrifuge! But only Wadia refuses to play such CDs.
sevs

Showing 3 responses by sevs

@kijanki Thank you for responding!! These last few years I got myself a hobby of reviving 1st generation Discmans. Have seen "all of the above" :-(

A few days ago I finally cracked and send an email to Steve Huntley, the designer of my Wadia (he is now with Resolution Audio). His response is below (posted without his permission, of course):
"There is a large variability in CD manufacturing and if the disc is not perfectly circular, or the center hole is off, or the pits are not equally spaced to the center hole its much harder for the player (laser and servo circuitry) to read it. So the lathe (Audio Desk Systeme CD Lathe) is exactly the right solution. Nothing specifically wrong with the Wadia...just picky about the discs it plays. Unfortunately discs themselves are not held to tight standards of manufacture."
"Of course a discman is designed to play anything and while the unit is jumping around all over the place....not exactly the design criteria of a Wadia mechanism. Also units (low cost players) have huge amounts of error correction going on so they can play CD's with peanut butter and jelly on them, kids finger prints, etc! That error correction does not help the sound....the less error correction the better. So again just a totally different design criteria."

What you and SH said confirms my suspicion that when I adjust Focus/Tracking gain, at low settings it skips easily but sounds better. Maybe unrelated, being spoiled by Wadia and Naim CDS3 it is difficult for me to judge the nuances of Discman's sound. 
@kijanki I bought all the books I could find on CD players maintenance and repair, most of them have a few pages on how pits are transformed into sound. If there is anything you can suggest on the theory of different DACs and error-correction, please let me know.


I did buy Staedtler 350 Lumocolor marker in Green.
Funny thing, once I treated hybrid SACD of Grieg Piano Concerto with this marker, its SACD layer got busted: starting at track 2 it skips and stalls. CD layer is OK. This proves, I guess, that using green marker does have some effect.
Someone joked that Green is for the Spring/Summertime edge-painting, I shall try flat black tomorrow. 
Today I gutted one cheapo Discman, what is left is just a spindle motor and plastic bottom half of the player. Connected spindle motor to variable DC. At 2V / 1000+rpm some CDs make this CD-centrifuge vibrate like crazy (e.g., all CDs from German "Brain" label), some are perfectly centered (4AD label). Wadia refuses to play only eccentric CDs, treatment with AudioDesk CD lathe cures some CDs, and lowers vibration on some.
Oh, and it plays CDR, CDRW and scratch-test CD without any problems

Wadia is practically not used: until a week ago I always used Naim CDS3 for CDs. But I will open it up tomorrow (I did this before, to reset its "gain" switches) to check its CD mechanism.

Cannot wait to get to the fun part of different color markers for CD edges!!!   :-)