Please help interpret C2 errors on pressed discs

[exchelente]

I got my pressed discs back from the plant. After noticing some weird looking dye colorations on the bottom, I had my ME run plextools c1/c2/cu test. Below are the results. We didn't see any C2 errors on the master disc provided to the plant. Is this acceptable or not?
Thanks!

[GooberNumber9]

I don't really know, but I'm posting to suggest you run the same test on some big-label CDs and see how the results compare. If you find that on average the big label CDs have far fewer errors, you could call your duplicator and ask them if there's a reason why your pressing seems to be worse than what you expected.

In the last ten minutes I did some research that I think says that:

1) The total of C1 and C2 errors is (I think) the BLock ERror Rate.
2) Your average BLER is 1.7 errors/sec, and that's pretty good.
3) Your max # errors in one second is still less than 2%, and less than 3% is required for a valid disc.

Try playing the disc in a bunch of players and see if you have any problems, and see if it SOUNDS ok!

Todd Wilcox

[MASSIVE Mastering]

I'd call up and pitch a fit. Are *all* the discs like that or just the one?

And these are pressed -- as in, polysubstrate with an aluminum reflector and not a CD-R (the word "dye" had me there for a minute)?

Your C1's are within norms. You shouldn't have any C2's. A CU would be a show-stopper.

[exchelente]

Thanks Todd and John. Yes, these are pressed (replicated) and not CD-R's. They all have the same weird look to the bottom of them (at least all 30 I've seen, haven't opened shrink wrap on the other 970, haha)

I tried to take some pictures to show you the weird wave thing on the bottom

[GooberNumber9]

I've seen that on commercial CDs before, but I think you should listen to John. He's a mastering engineer and I'm just talking out of my butt. Let us know how the duplicator handles the situation, good or bad.

Todd Wilcox

[Mradyfist]

When my old band put out their last EP, we pressed 1000 and when they came back we had a LOT of trouble getting them to play consistently in car CD players. I don't remember actually getting the problem figured out, if I recall correctly the replication guys blamed it on our mastering guys and vice versa. Nobody ended up taking responsibility for the situation.. I was inclined to believe our mastering engineers because I had worked more closely with them, but who knows..

[MASSIVE Mastering]

Am I seeing what looks like a circular "skid mark" on the disc that goes from wider near the center to narrower towards the edge?

Yeah, I'd call the plant on that one...

[Cellotron]

The test on that replicated CD actually shows it pretty well within the specs of many plants - both the C1 (a completely correctable error) maximum & average rates are actually pretty darned good - and you're definitely not going anywhere near the 200 maximum in a second that is actually allowable in Red Book Spec.

The presence of C2's doesn't necessarilly make the replicated discs readily suitable as a replication master as some plants pre-tests will flag them as being out of spec - but again C2's are indeed completely correctable by nearly all CD tranpsorts and when they appear in short bursts such as indicated in your test they most often appear in a greater number than C1's when they are present - so while I wouldn't personally send in something that tested in this way to a plant as a master disc - again for a plant replicated disc the test result isn't really sending off alarms to me.

In other words - the presence of these kind of numbers of C2's on a disc -while not something you want on a master - are generally no big deal on a replica.

I'd check other discs and see if any of them have CU's - which would be a true indicator of a problem.

If the discoloration exists the same on all the CD's that possibly could be a stain on the stamper that happened in the developing or plating. If the discoloration occurs only a few CD's and is different in each of them then perhaps it occured from a dirty stamper, contaminants in the polycarbonate, slightly incorrect process timings, or uneven temperature in the molds of the press. I'd sample 1 from each box and see if the problem is consistent (I'm guessing from your description it most likely will be).

I would bring up the problem with the plant and see whether they can provide you a discount for what I think is the result of a mild stain on the stamper - but I'd be prepared for the possibility that the plant will find the discs are within their specs.

My own thoughts are that unless you are finding CU's in your test that the discs will most likely play in the vast majority of players without a problem - but you might want to actually play them in a variety of transports (i.e. cheap car stereos, portables, old players, etc.) to confirm this.

Just as a background on my post: I was a production manager at a pressing plant for about 6 years, and work as mastering engineer now.

Best regards,
Steve Berson