CD Error Correction Tests

In the following tests we check the drive's behavior when reading scratched / defective audio discs. The test discs used were the ABEX series from ALMEDIO.

- ABEX TCD-721R

Errors total	Num: 3081650
Errors (Loudness) dB(A)	Num: 130508	Avg: -74.0 dB(A)	Max: -35.7 dB(A)
Error Muting Samples	Num: 9335	Avg: 1.0 Samples	Max: 40 Samples
Skips Samples	Num: 0	Avg: 0.0 Samples	Max: 0 Samples
Total Test Result	69.8 points (out of 100.0 maximum)
C2 Accuracy	99.9 %

At first glance, the performance with this disc does not seem good. Most drives start producing errors at least after having passed the 12 minute mark. The total error count is very high, but the maximum loudness error level of -35.7dB is quite reasonable (although higher than that reported for the ND-2500A) and the muting samples count is low while there were no skipped samples. The final score of 69.8 is rather good.

- ABEX TCD-726

Errors total	Num: 394060
Errors (Loudness) dB(A)	Num: 23453	Avg: -77.7 dB(A)	Max: -25.1 dB(A)
Error Muting Samples	Num: 1298	Avg: 7.7 Samples	Max: 2946 Samples
Skips Samples	Num: 2	Avg: 6.0 Samples	Max: 6 Samples
Total Test Result	71.4 points (out of 100.0 maximum)
C2 Accuracy	99.7 %

The Abex TCD-726 test disc is much easier for drives in general to read. That's why the ND-2510A performed better than with the previous CD, but again there is a high total error count and in general there are way too many errors for this disc. The final score of 71.4 is very low and indicates not very good performance here.

- CD-Check Audio Test Disc

The CD-Check Test Disc is a very useful tool for evaluating the Sound Reproduction / Error correction capabilities of a CD player. The disc offers a signal combination with disc error patterns to rate the drive's abilities to read music and reproduce it completely. Five tracks on the disc contain a sequence of progressively more difficult tests. These tracks are referred to as Check Level-1 through Check Level-5.

The tracks are being reproduced through a software multimedia player (i.e. Windows Media Player). Each level is considered as passed, if the tone is smooth, continuous without interruptions, skipping or looping. The higher the Check Level passed, the more reliable the sound reproduction of the tested drive.

Error Level	1	2	3	4	5
NEC ND-2510A	5/5	5/5	3/5	0/5	0/5

The drive successfully passed only the first two out of the five check levels for this test. An average drive will pass the third level and the better drives will reach the fourth or even fifth levels. Again, this is very disappointing performance from NEC.

- Summary

Generally we can say that the CD error correction capabilities of the NEC2510A are average and should be fixed with newer firmware updates...