tracking test discs

[duncan]

I vaguely remember back in the day that there were reviewers (Audio magazine, maybe?) who tested players' ability to read damaged CDs using some kind of test disc designed to be more difficult to read as you advanced through the tracks.

That got me thinking just now; it might be nice to have something of the sort that was standardized as an evaluation tool. Does it already exist anywhere? Or is there nothing to do other than keep track of our personal collections and set aside stuff that's been inadvertently scuffed and scratched -- or maybe creatively defile a sacrificial disc or two?

(Word to the wise: don't search for "torture test DVD" on ebay. You'll be looking at other stuff.)

 

[swechsler]

The problem is definitively defiling the sacrificial disks. I never saw one, but it's my understanding that these test disks were precision manufactured, and you'd be unlikely to be able to reproduce something on your own.

Actually, scratches on the playable layer can usually be buffed out unless they're unusually deep. The problem is when you get scratches on the printed layer, at which point you'll probably have to throw the disk away. Luckily, DVDs are a lot more durable in this regard; even though the plastic between the playing surface and the data is half as thick as on a CD, the actual data is pretty well protected since it's in the middle rather than on the top like with a CD.

 

[CharlieX]

The French music label Pierre Verrany did a 2-CD set of digital demonstration music with sound effects. The second disc has an assortment of frequency sweeps and test tones. It also a section of embedded data layer drop-outs of increasing sizes to test CD players' tracking abilities.

 

[KentTeffeteller]

The French music label Pierre Verrany did a 2-CD set of digital demonstration music with sound effects. The second disc has an assortment of frequency sweeps and test tones. It also a section of embedded data layer drop-outs of increasing sizes to test CD players' tracking abilities.

Kept this set of discs for years in the workshop as this set was so useful for assessing the condition of incoming CD players.

 

[KentTeffeteller]

I vaguely remember back in the day that there were reviewers (Audio magazine, maybe?) who tested players' ability to read damaged CDs using some kind of test disc designed to be more difficult to read as you advanced through the tracks.

That got me thinking just now; it might be nice to have something of the sort that was standardized as an evaluation tool. Does it already exist anywhere? Or is there nothing to do other than keep track of our personal collections and set aside stuff that's been inadvertently scuffed and scratched -- or maybe creatively defile a sacrificial disc or two?

(Word to the wise: don't search for "torture test DVD" on ebay. You'll be looking at other stuff.)

One of the Philips Test CD discs had deliberate damage for this purpose to assess a CD player's performance in the workshop.

 

[duncan]

I wonder if the Philips or Pierre Verrany discs are still available anywhere. But my situation here had me thinking more about something equivalent in DVD form.

A recently acquired Sony NS900V couldn't get through a certain hybrid SACD borrowed from the local library, whereas another identical player in the house had no trouble with it from start to end. The usual maintenance steps (clean lens, clean/lube sled rails, lube spindle motor) didn't help, and neither did the alignment procedure in the service menu. It was also occasionally skipping on some other SACDs, so I suspected the laser pickup was probably reaching end of life. New pickups being unavailable, I went looking for a cheap donor DVD player from around the same age (NS400D) that had the same part. Swapping that in was easy surgery, a short job, just six screws and three ribbon cables. And it worked worked perfectly immediately, no realignment needed, so that's nice, but I also thought about how useful a disc like that could be. 12 tracks, undamaged at the middle, and before the laser replacement it would start to skip around track 6 and then could never get past track 8 or so. There had been no trouble tracking the CD layer, I assume because the player's CD laser was still running at pretty close to full strength.

I can't imagine intentionally damaging any of my personal SACDs, but since optically I understand they're essentially DVDs, for future reference I might sometime try to make tracking torture tests out of one or two old videos we don't watch anymore.