Interpreting CU errors in PlexTools

vbimport

#1

I’ve begun running tests on some of the hundreds of audio CD-Rs in my collection, using Plextools Professional XL V3.16 C1/C2/CU diagnostic software. For the most part, my silver mitsui CD-Rs from 2001-2002 seem to have held up pretty well (zero CUs). But when discs do fail, there is almost always a large amount of CU errors concentrated at the end of the audio (~50-55 min).

I’m just not sure why – technically – there would be more errors towards the end of the recorded audio. I assumed errors (if resulting from the dye layer fading/degrading) would be random throughout the disc, not gradually increasing like I’m seeing.

The only thing I could think of is that the laser angle changes when writing the info on the outside of the disc, and then somehow creates instability? Just wondering if anyone have any other ideas!


#2

When the discs are made the dye layer is applied near the centre of the spinning disc and distributed by this action.
So with any errors like lack of dye, viscosity or spin speed the problem would be more likely to occur towards the outside of the disc.

Any disc faults I have had always to seem to get worse toward the end.

See this interesting video about blank disc manufacture:
https://www.youtube.com/watch?v=497FemsGVS0

Dye application about 2.20 in.


#3

[QUOTE=Sonic2171;2729681]When the discs are made the dye layer is applied near the centre of the spinning disc and distributed by this action.
So with any errors like lack of dye, viscosity or spin speed the problem would be more likely to occur towards the outside of the disc.

Any disc faults I have had always to seem to get worse toward the end.

See this interesting video about blank disc manufacture:
https://www.youtube.com/watch?v=497FemsGVS0

Dye application about 2.20 in.[/QUOTE]

I like this explanation! Thanks for the insight! J