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: 1521355
Errors (Loudness) dB(A)	Num: 160496	Avg: -79.5 dB(A)	Max: -16.0 dB(A)
Error Muting Samples	Num: 6038	Avg: 1.4 Samples	Max: 563 Samples
Skips Samples	Num: 90	Avg: 6.0 Samples	Max: 6 Samples
Total Test Result	62.0 points (out of 100.0 maximum)
C2 Accuracy	96.9 %

The maximum error loudness level was high at -16.0dB and there were 90 skipped samples. This indicate poor CD error correction capabilities.

- ABEX TCD-726

Errors total	Num: 8595
Errors (Loudness) dB(A)	Num: 6634	Avg: -86.0 dB(A)	Max: -15.2 dB(A)
Error Muting Samples	Num: 164	Avg: 11.2 Samples	Max: 467 Samples
Skips Samples	Num: 1	Avg: 6.0 Samples	Max: 6 Samples
Total Test Result	75.6 points (out of 100.0 maximum)
C2 Accuracy	98.1 %

Although the Abex TCD-726 test disc is much easier for drives in general to read, the NEC burner 's performance does not indicate high error correction. There was only one skipped sample, but the drive managed a total score of 75.6 where better drives manage scores closer to 100. In general, the drive's CD error correction capabilities need to be further improved.

- 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-3520A	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. Here too, the drive turned in a poor performance. Almost all drives have difficulties reading the 5th level but good quality drives can read up to the 4th level. However, most drives will pass at least the third level without any problems.

- Summary

Generally we can say that the CD error correction of the NEC ND-3520A is not good, something that could be fixed with newer firmware releases.