Q-Check: C1/C2 CD-R test?


As an old DJ (still play), I’ve taken all my records from start to end, and scanned lots of them with the C1/C2 test. But I’m unsure about what the C1, C2 actually are telling me? I know that there is always C1 errors, and sometime (most times) some C2 errors, and that my drive can correct them. But how can I really tell, If I need to copy a CD to a new one. I know the red once are scratches or other physical surface problems, and for sure need a new CD, if possible to read the damage area.

But looking at C1’s and C2 errors, when do I need to think of copying the disk to a new one?

Okay, I have found what I’m looking for by searching on the forum, sorry :doh:


When a CD shows C2 errors (and no CU errors), it is time to make a backup: The CD can still be losslessly recovered.

When a CD show CU errors, it might be too late

Thanks AlexNoe,

Yes, I have some CD’s with CU errors, and I can’t copy them with plextools, nomatter how many retries I make. Uncorrectable physical errors on the surface from deep scratches :sad:

The light surface scratches from taking a CD out and in of a CD sleeve, can nearly always be fully recovered by copying the CD to new media, if its not too scratched.

C1 errors will always be there, but not many on a new quality CD. I have bought some bad pressed CD’s, where the C1 and C2 values was pretty high from the beginning. So even though I bought these CD’s pressed with music on them, they are not always of a superb quality. Many times you can see that the edges starts to be very flussy and ugly, which probably means problem when reading them.

I have to find out how big the C1, C2 error peaks aprox. should be, before I need to burn it to a new media.


have bought some bad pressed CD’s, where the C1 and C2 values was pretty high from the beginning.
Some CDs are intentionally designed to have bad playback quality and show CU errors from the beginning. This is called “cactus data shield 200”. Especially EMI is selling such crap

If the CDs are very important to you, and by this I mean that they are worth more than the price of buying an additional drive, then you could try recovering the CDs on a LiteOn drive (CD burner or DVD burner). LiteOns are well known for being able to read discs that most other drives can’t read. This doesn’t guarantee that they will read your discs, however.

If you decide that you want to spend money on trying this, then I suggest you ask over in the LiteOn forum about which LiteOn drive is likely to be the best reader.

My LiteOn SHW-1635S can read some discs that my other drives can’t read, but that doesn’t mean that it is necessarily the best choice for the task.

Thanks DrageMester,

I didn’t know about the reading skills of the LiteOn drives, thanks for telling. No, its a very limited about of CD’s I have, that have very high C2 peaks or CU errors, so I probably end up buying those Cd’s again, if I need them. I have checked most of my Cd’s that I have with me when I’m DJ’ing. They are not optimal sealed in those plastic CD sleeves I use, but only 3 of them had CU error, and two of them was homemade - burned on TEAC CDs back in the 90s. And I have the vinyl records, so not a problem.

But I’m really surprised about some of the pressed audio CDs, that in fact are very scratched, and looks like a replacement. But to my surprise some of them doesn’t have any C2 errors and only a few C1 errors. I guess the pressing and media must be of a very good quality :rolleyes: