48x CD-RW Combo Roundup Vol.1 - Page 4

Error Correction Tests

Optorite DC4801

In the following tests we examine the behavior of the Optorite DC4801 with respect to scratched/defected CD-R media. The drive initially rips the contents of a pressed audio disc (non-defect), and the resultant .wav file is stored onto the hard disk. Afterwards, the ripping procedure is repeated, but this time, the inserted disc is artificially scratched (ABEX TCD-721R) or defected (ABEX TCD-726). The recorded contents of all the test-discs are the same. Both original and defected .wav files are compared through the software provided by the author of the EAC software.

The more identical the extracted .wav file is with respect to the original, the better error correction / error concealing capabilities the tested drive features.

- ABEX TCD-721R

Errors total	Num: 402587538
Errors (Loudness) dB(A)	Num: 1884092	Avg: -24.1 dB(A)	Max:-3.7 dB(A)
Error Muting Samples	Num: 762087	Avg: 4.8 Samples	Max: 3584 Samples
Skips Samples	Num: 0	Avg: 0 Samples	Max: 0 Samples
Total Test Result	67.3 points (of 100.0 maximum)
C2 Accuracy	50.1 %

According to the graph, the signal had a high average level (-24.1dB(A)) and its maximum value was -3.7dB(A). According to the EAC author, the calculation of these parameters does not include any particular acoustical model. This means that the high dB(A) values do not have a direct connection with respect to the acoustical output of your speakers. However, testing has showed that the acceptable Error level should be below -60dB(A). In our case, although the drive reported high error rates, many of them were muted by the drive itself. As a result, the total score in the test is not very bad, reaching at 67.3 points out of 100.

The same software reports that the Optorite DC4801 offered a 50.1% of C2 accuracy, by using the particular test disc.

- ABEX TCD-726

Errors total	Num: 74531
Errors (Loudness) dB(A)	Num:11829	Avg: -79.4 dB(A)	Max:-20.5dB(A)
Error Muting Samples	Num: 515	Avg: 2.8 Samples	Max: 43 Samples
Skips Samples	Num: 0	Avg: 0.0 Samples	Max: 0 Samples
Total Test Result	79.0 points (of 100.0 maximum)
C2 Accuracy	66.4%

The ABEX TCD-726 test is always easier to handle for most drives. The errors reported were less than that in the previous test. The average level was low (-79.4dB(A)). Some erroneous samples were muted, and no synchronization problems were reported (samples skipping). The score in this test is good, 79.0 points out of 100 and the C2 accuracy is thus determined to be 66.4%.

- Conclusion

Test Disc	Reading Speed	Score
ABEX TCD-721R	Max	67.3
ABEX TCD-726		79.0
Average Score		73.15

The Optorite DC4801 gave back a quite good score 73.15 out of 100 at the reading error correction tests. The drive seems to be able to rip the scratched areas of the test disc at maximum speeds, reporting high error rates, but most of them were successfully concealed. The behavior of the drive with defected discs was also good, as it was able to rip the contents of the discs accurately. On the other hand, the reported C2 accuracy is not high.

- Nero CDSpeed test

- ABEX 721R

Nero CDSpeed test confirmed the results we got from the EAC test suite. The reported quality score of the drive is good, 89.7, while the C2 Accuracy is not even close to 100%, as it was expected.