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: 1456413
Errors (Loudness) dB(A)	Num: 173349	Avg: -80.3 dB(A)	Max: -18.6 dB(A)
Error Muting Samples	Num: 5992	Avg: 1.2 Samples	Max: 18 Samples
Skips Samples	Num: 34	Avg: 6.0 Samples	Max: 6 Samples
Total Test Result	64.1 points (out of 100.0 maximum)
C2 Accuracy	98.5 %

The drive did not perform well with this test disc, giving high loudness level (-18.6dB) as well as a high overall error total. The Total Test Result score of 64.1 is also somewhat disappointing.

- ABEX TCD-726

Errors total	Num: 8435
Errors (Loudness) dB(A)	Num: 12256	Avg: -85.3 dB(A)	Max: -11.4 dB(A)
Error Muting Samples	Num: 322	Avg: 4.2 Samples	Max: 18 Samples
Skips Samples	Num: 2	Avg: 6.0 Samples	Max: 6 Samples
Total Test Result	73.4 points (out of 100.0 maximum)
C2 Accuracy	94.7 %

Usually, most DVD burners can read more easily the Abex TCD-726 test disc, but again, the NEC ND-6500A had problems reading this disc. The drive managed to compile a score of 73.4, which is rather low.

- 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 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-6500A	5/5	5/5	2/5	0/5	0/5

Again, the NEC ND-6500A did not perform well with this test disc. Although the fifth track is not easily read by most burners, we expected to read at least track 3 without problems. However, the NEC burner passed only the first two out of the five check levels for this test.

- Summary

Unfortunately, CD error correction with the ND-6500A is below average. Since this NEC model is used as a notebook internal drive, it is meant to be used as a reader as well. We expected to see better performance from a drive of this kind.