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Appeared on: Sunday, April 20, 2003

1. Introduction - Package

Duet CD-R2-U2 slim CD-RW/DVD combo - Page 1


We have in our hands the new Duet CD-R2-U2 drive. It is a slim portable CDRW/DVD combo drive, provided by Dynamic System Electronics Corp.

Dynamic System Electronics Corp was first established in 1998, and is specializing in research and development, manufacturing and selling of computer accessories. The company mainly produces external cases for optical storage drives, card readers, flash memory drives, external CDRW/DVD combo's, as well as other PC accessories.

The Duet is a portable slim combo drive, which offers CD-R/RW writing along with DVD reading capabilities. As all the devices of this type, the drive is an alternative solution for Notebook and desktop PC use.

- Drive features

The supported writing speeds are 4x and 8x (CLV), 12x, 16x, 20x and the maximum 24x (Z-CLV). The 24x (CAV) speed is the supported reading speed for the CD-R and the HS-RW media, which can be written at 12x (Z-CLV). The maximum reading speed for DVD-ROM is 8x CAV ( 1.7x ~ 8x ).

All the supported reading/writing speeds are illustrated below:

The Duet drive supports the USB 2.0 interface. For writing/rewriting, the SMART-BURN® function and the 2MB cache buffer both help avoiding buffer under run. These functions can also help getting the best writing quality by smartly adjusting the writing strategy. Besides, the SMART-X function smartly adjusts CD-DA/VCD/DVD data extraction to a faster speed according to both data request rate from the host and the disk quality. The drive is compliant to the RPCII regulations, allowing the user to change the region code of the drive at most 5 times.

The supported disc formats are: DVD-ROM (single layer/dual layer), DVD-R, DVD-RW DVD+R, DVD+RW, CD-DA, CD-ROM, CD-ROM/XA , Photo-CD, Multi-session, Karaoke-CD, Video-CD, CD-I FMV, CD Extra, CD Plus, CD-R , and CD-RW. The supported writing formats are the DAO, SAO, TAO (Disk-Session-Track at once respectively) and fixed/variable packet writing.

- The package

The retail package includes the 24x combo drive, a USB 2.0 cable, and a Power AC Adapter. The attached CD-ROMs contain the USB storage drivers for Win98 users, Nero Ver.5.5 for Windows, In CD packet writing software and a User manual in English. The package does not include any blank CD-R/RW media or any software for DVD playback.

The dimensions of the drive are 20.4 x 148 x 151 mm (WxLxH) and its weight is approximately 500gr.

The severe design of Duet provides a stylish overall appearance, combined with its very slim structure. The basic colors of the drive are the black and white. As you can see in the picture above, the "Duet" and CD-R/DVD-ROM logos are stamped on the top panel. From this view the power/status LED is also visible.

On the front panel of the drive there is the disc loading tray, the eject button, the emergency eject hole and the busy LED indicator.

On the rear panel there is the USB 2.0 interface and the power adapter ports.

- Installation

The Duet drive was connected to our test PC through the USB 2.0 interface, and was identified as "Slimtype COMBO LSC-24081" under WinXP. The drive came with firmware v3M06 installed and it was used to make all the reading/writing tests.

In the test graphs, we compare the new drive with an already tested slim combo drive, the INcoder TS24C-C1.

2. Data CD Reading Tests

Duet CD-R2-U2 slim CD-RW/DVD combo - Page 2

Data CD Tests

- Pressed CD results (Click to see the CD Speed Graph)

Duet LSC-24081 supports 24x CAV reading for CD-ROM/R media. The drive read the inner part of the disc at 11.44x and gradually accelerated to finish the task at 24.33x, resulting to an average speed of 18.6x. The INcoder TS24C-C1 also performed well and gave a slightly lower average reading speed.

In the same task the Duet drive gave low seek times, as you can see in the above chart. In the Random and 1/3 modes the drive gave the same results as the competitive INcoder TS24C-C1, but in the Full seek mode it performed even better with only 165msec for the Full seek job.

- CDR Media results (Click to see the CD Speed Graph)

CD-R media was also read fast, with the Duet drive giving a 18.39x average speed. Although the INcoder drive finished reading at a higher speed than the Duet, it started at 10.23x and this had a negative cost in the average reading speed. We can say that both drives performed very well.

In the seek test, the results for the Duet LSC-24081 were almost the same as in the pressed CD test. On the other hand, the INcoder drive was improved giving better performance.

- HS-RW media (Click to see the CD Speed Graph)

For the RW tests we used the Ricoh HS-RW media. The Duet drive supports 24x HS-RW reading speed. The drive was fast and finished the test with 18.59X average speed. The INcoder drive behaved in a similar way and achieved at the average 18.79x.

3. CD-R Error Correction Tests

Duet CD-R2-U2 slim CD-RW/DVD combo - Page 3

Error Correction Tests

In the following tests we examined the error correction capabilities of the Duet LSC-24081 when reading recorded CD-R's.

- EAC CD-R Test Disc

Errors total Num: 174938590
Errors (Loudness) dB(A) Num: 853104 Avg: -25.1 dB(A) Max: -2.1 dB(A)
Error Muting Samples Num: 922088 Avg: 17.3 Samples Max: 3584 Samples
Skips Samples Num: 356 Avg: 43.9 Samples Max: 2934 Samples
Total Test Result 47.2 points (of 100.0 maximum)

Duet LSC-24081 gave back many errors. Most of them resulted to output muting. This means that the errors were uncorrectable, or even skipped. The performance is low and the average score is only 47.2 points out of 100.


Errors total Num: 1354115
Errors (Loudness) dB(A) Num: 57624 Avg:-70.2 dB(A) Max: -8.4 dB(A)
Error Muting Samples Num: 4430 Avg: 3.0 Samples Max: 1149 Samples
Skips Samples Num: 10 Avg: 16.8 Samples Max: 48 Samples
Total Test Result 65.1 points (of 100.0 maximum)

This time the drive gave less errors than previously, but the score is still lower than average. The Loudness errors reached the -8.4 dB(A) and had an average value of -70.2 dB(A). In addition, 4430 samples were muted.

- ABEX TCD-726

The drive gave an average of 76 points out of 100. This time the "errors loudness" occurred were less, and their average level is low, -39.7dB(A) average. No samples were muted but 6 of them were skipped.

Errors total Num: 43
Errors (Loudness) dB(A) Num: 64 Avg: -39.7 dB(A) Max: -14.3 dB(A)
Error Muting Samples Num: 0 Avg: 0.0 Samples Max: 0 Samples
Skips Samples Num: 6 Avg: 538.0 Samples Max: 588 Samples
Total Test Result 76.0 points (of 100.0 maximum)

- Conclusion

Test Disc Reading Speed Score
ABEX TCD-721R 65.1
ABEX TCD-726 76.0
Average Score 62.76

The Duet LSC-24081 gets an average score of 62.1 out of 100 at the reading error correction tests.

- C2 Information accuracy

The drive missed 46342 C2 marks and gave 411 sync errors. The quality score is 71.9 which is an average score, and the C2 accuracy is 97.33%.

4. DVD Reading tests

Duet CD-R2-U2 slim CD-RW/DVD combo - Page 4

DVD reading tests

- Single Layer DVD-ROM reading: (Click for CDSpeed results )

Duet LSC-24081 supports 8x CAV maximum reading speed for the DVD format. The drive reached the 8.28x reading speed by the end of the task, and gave an average speed of 6.19x. The INcoder TS24C-C1 gave almost the same average speed (6.10x).

The seek times of the Duet drive are very good. The random seek test gave an 103 msec result, and the Full seek around 180 msec. The INcoder drive seems to be faster in the Full stroke seek test.

- Dual Layer DVD-ROM reading: (Click for CDSpeed results)

The drive supports 6x CAV reading speed for the dual layer DVD-ROM discs. The average reading speed for each layer is 4.33x, while the INcoder drive is slower with just 3.17x reading speed.

The Duet drive gave higher seek times with CD-R discs than with pressed ones. However, the performance is still quite good. In the same test, the Incoder drive is faster in the Random and 1/3 seek tests.

- DVD Ripping Tests

We measured the DVD Ripping speed using the "Matrix" DVD Video title and the DVD Decrypter software.

The ripping speed of Duet drive is very low. The average speed is only 1,996KB/sec which is approximately 1.4x. The INcoder drive is much faster with 4,628 KB/s.

- DVD reading Tests

The chart below shows the Nero CDSpeed results with the following media.

The Duet LSC-24081 read all the inserted discs at an average speed of 4.3x, except of the DVD+R discs, where it was faster (5.55x). The INcoder drive is slower with the DVD-R/RW media but faster with the DVD+R.

5. DVD Error Correction Tests

Duet CD-R2-U2 slim CD-RW/DVD combo - Page 5

DVD Error Correction Tests

In the following tests we examined the DVD error correction capabilities of the Duet LSC-24081. For the tests we used CDVD Benchmark v1.21 and Nero CDSpeed . The reference test media comes from ALMEDIO.

- Single Layer media

This is a single sided, single layer DVD-ROM with a 4.7GB capacity, in which there are scratches with dimensions ranging from 0.4 to 3.0 mm. The following transfer rate picture comes from CDVD Benchmark v1.21.

The Duet seems to have no problem finishing the reading task with no errors. The drive lowered the reading speed to an average of 5x when it reached the 500,000th sector, according to the software. The reading speed was kept at 5x until the end of the reading process. No read errors occurred.


This is also a single sided, single layer DVD-ROM with a 4.7GB capacity. The data structure of the disc is exactly the same as of the TDR-821, with the difference being that there are no scratches on it, but defected areas with dimensions ranging from 0.5 to 1.1 mm. There are also fingerprints sized from 65 to 75 micro meters.

The drive did not have any problems to read the disc contents. The yellow dots correspond to the current speed in each area of the disc. The CDVD software reads each sector multiple times and decides the average value for the main graph. No read errors were reported.

- Dual Layer media

This is a 8.5GB dual layer, single sided DVD-ROM disc with artificial scratches with dimensions ranging from 0.4 to 3.0mm, in both layers.

Again no read errors occurred, but looking at the graph you can see that the drive read each sector in many different speeds (yellow dots). This means that the task was not very easy for the drive but the result is adequate.


The disc is a single sided, dual layer DVD-ROM disc with a capacity of 8.5GB. The only difference between the TDR-845 and the TDR-841 is that the first includes defected areas and fingerprints. The dimensions of the defected areas rang from 0.5 to 1.1 mm and the fingerprints are sized between 65 to 75 micro meters.

As in the corresponding test with the ABEX TDR-825 (defected single layer DVD-ROM), the drive had no problems to finish the task successfully. The reading speed was again set to 5x by reaching the middle of the capacity of each layer.


The TDV-541 is a single sided, dual layer DVD-VIDEO disc, with a capacity of 8.5GB. The disc is based upon the TDV-540 series which is designed for inspection and adjustment of DVD-VIDEO players. The discs check the layer switch operation from layer 0 to layer 1 and also include test pictures and test signals for DVD sound files. The current TDV-541 checks also the error correction capabilities of the drive and includes scratches from 0.4 to 3.0 mm.

The drive gave a 4.36x average reading speed for the DVD-Video format. The scratched areas forced the drive to slow down momentarily, but it seems that there were no reading problems.


The TDV-545 disc is based on the TDV-540 series. It is a single sided, dual layer DVD-VIDEO disc with a capacity of 8.5GB. The TDV-545 includes artificial black dots on the data surface, sized from 0.4 to 1.0 mm. It has also 65 - 75 micro meters fingerprints on the reading surface.

Black dots and fingerprints were not a problem for the drive. The test was successful, at a 4.42x average speed .

6. CloneCD Reading Tests

Duet CD-R2-U2 slim CD-RW/DVD combo - Page 6

CloneCD Reading Tests

- Procedure

We used CloneCD and 3 original CDs - Serious Sam 2 (SafeDisc 2), V-Rally 2 Expert (SecuROM 2) and NBA Jam Extreme (PSX) - in order to test the reading time of the drives. The following pictures show the drive reading/writing capabilities as CloneCD reports them:

- PSX Pressed Media

For this test we used the PSX game 'NBA Jam Extreme' and we ripped the image to the HD with CloneCD. Duet LSC-24081 needed more time than expected to finish the task. The 352sec needed is less than the average performance we usually get from the drives. The INcoder TS24C-C1 is faster and finished in 122sec.

- SafeDisc v.2 Results

Contrary to the PSX reading test, the SafeDisc v2.0 protected disc was read faster than the INcoder drive. The Duet LSC-24081 finished the tasks in approximately 12min .

- SecuROM Results

Both drives can read SubChannel data from Data/Audio tracks, but the TS24C-C1 does not support 96 bytes of Subchannel data (CD+G). 4:16 minutes were enough for the drive to make the image file to the hard disk. The average reading speed is 17.1x, and the Incoder drive is slightly slower in this case.

7. DAE Tests

Duet CD-R2-U2 slim CD-RW/DVD combo - Page 7

DAE Tests

- DAE features

EAC reports that the Duet drive supports caching of data, "Accurate Stream" and that it is not able to retrieve any "C2" error info.

- Pressed AudioCD results

In this test we examine the DAE speed of the drive. The Duet LSC-24081 ripped the audio files at an average of 17.5x. The ripping speed is not bad for a 24x reader. The Incoder drive is slower at 10x average reading.

- CDR AudioCD results

With CD-R media, the average ripping speed again is 17.5x.

- EAC Secure Extract Ripping mode

EAC's "secure extract mode", ensures maximum produced WAV quality for ripping audio discs. Note that for each drive we used the build-in detection function:

Tested Drives Average DAE Speed (X)
Pressed CDR
Duet LSC-24081 2.5 2.6
INcoder TS24C-C1 9.6 9.7

The Duet drive was slow in this task, mainly because of the "Caching" feature supported by the drive. This affects the reading speed under the EAC "secure" ripping mode. The Incoder drive is faster in this task with a 9.6x ripping speed on pressed discs and 9.7x for recorded ones.

- Advanced DAE Quality

Duet LSC-24081 got a 100 score (perfect) in the Nero CD Speed Advanced DAE test. The CDSpeed showed that the average reading speed is 17.16x, and that the drive can also read SubChannel data and CD Text. On the other hand, the INcoder drive had some problems and it produced 7,050 data errors.

- Ripping of 99mins AudioCD's

Tested drives Ripping up to
Duet LSC-24081 OK
INcoder TS24C-C1 Up to 88min

- Reading/Ripping Protected AudioCD's

For this test procedure we used 2 protected AudioCD's, which we tested in both recognition and ripping (using the respective EAC features):

* Pressed AudioCD with Sony Key2Audio (Celine Dion - New Day Has Come)

* Pressed AudioCD with Cactus Data Shield 200 (Natalie Imbruglia - White Lilies Island)

Key2Audio CDS200
Duet LSC-24081 Cannot recognize disc Recognizes disc contents but cannot rip them
INcoder TS24C-C1 Recognize disc contents, but rips the first 5 tracks only Recognizes disc contents but not all files have high quality

Duet LSC-24081 is not a good solution to backup your Key2Audio and Cactus Data Shield 200 protected discs. The drive cannot recognize the Key2Audio discs at all , while in the case of the CDS200, it cannot again rip the disc contents, although they are recognized.

8. Recording Tests

Duet CD-R2-U2 slim CD-RW/DVD combo - Page 8

CDR Tests

We tested the drive using the latest version of Nero/CloneCD. The Duet LSC-24081 supports the 24x (Z-CLV) maximum writing speed.

The writing strategy is divided in 5 Zones, starting from 8x in the first minutes of the disc, accelerating to 12x@11min, up to 16x@21min, shifting to 20x@42min, and finally to 24x@67min until the end of the process. Due to the large number of steps for reach the 24x speed, the average writing speed is kept below 17x (16.27x). This is expected to result in high recording times.

- Recording Tests

We created a 80min data compilation disc under Nero Burning Rom (burning 700MB of data). As you can see, the drive needed 407 seconds to finish the task, and the duration is large in comparison to a 24x recorder. The explanation for this can be found in the CDSpeed graph above, where you can see the Z-CLV implementation of the drive. The INcoder TS-24C-C1 was faster, but the burned data was 79min, since the drive does not support overburning.

The following picture comes from Nero after a successful burning at 24x:

Writing at 16x also gave long writing times. Below is a screenshot of Nero writing at 16x:

The Duet drive is slower than INcoder TS24C-C1 in all the available writing speeds:

- Other features

Overburning Up to 99min
CD text reading/writing Yes

- CloneCD Writing Tests

The CloneCD software reports that the drive supports the DAO-RAW feature. For checking the drive's EFM correction status, we used 3 different game titles (based on different SafeDisc 2 versions) with the latest software patches installed. We used the drive as both a reader/writer at the maximum attainable reading/recording speeds. Two discs were burned for each game (Amplify Weak Sectors On/Off). The results are posted in the table below:

Game Title Tested Drive SD2 Build Settings
Amplify Weak Sectors On Amplify Weak Sectors Off
Max Payne v1.05 Creative 52X CD-ROM v.2.50.020 OK
Serious Sam - The Second Encounter v1.07 Creative 52X CD-ROM v.2.60.052 No
The Sims - Unleashed Creative 52X CD-ROM v2.80.010

The Duet LSC-24081 cannot handle all the versions of the SafeDisc 2 protections. It created working backups of SD v2.50.0.20 that played in all the drives we tried them. The backups worked with or without the "Amplify Weak Sectors" feature. However, the latest Safe Disc versions were hard to be overpassed.

9. Writing Quality Tests

Duet CD-R2-U2 slim CD-RW/DVD combo - Page 9

Writing Quality Tests

We used Taiyo Yuden 80min 48x CD-R media and burned the same AudioCD project (with CD-Text) at all available recording speeds between 12x-24x. Below you can see the 3T Pit & Land Jitter graphs.

- 3T Pit results

As we can see from the above graphs, the 3T Pit Jitter stays below the 35ns RED book limit for all the available recording speeds, except from the case of the 16x speed. In this speed, the jitter value reached 36nsec by the end of the disc. However, the value is not very high. Also notice that the jitter is increased as the drive jumps to the 16x writing speed. Generally, the results are adequate and it seems that there will be no problem writing even at the maximum supported 24x speed.

The average 3T Jitter values for all recording speeds are illustrated in the following table.

The 12x writing speeds gave the lowest average jitter values, and the 16x the highest. The average value of jitter is less than 35nsec for all the recording speeds. We could say that you can safely burn your favorite audio discs in any available speed.

- 3T Land results

The average 3T Land results are slightly increased over the the previous measurements of the 3T Pit Jitter. The maximum jitter values reported were 33ns, and came from the measurements at 16x and 24x recorded disc.

- Conclusion
Recording Speed 3T Pit Jitter (ns) 3T Land Jitter (ns) > 35ns Max value (ns)
12x 25.66 26.39 No 28 Pit, 33 Land
16x 32.02 31.59 Yes 36 Pit, 33 Land
20x 30.51 30.63 No 34 Pit, 32 Land
24x 29.61 30.23 No 32 Pit, 33 Land

The average 3T Pit and Land jitter values are below the 35nsec standard for all the recording speeds. The 16x recorded discs gave some slightly increased values but it seems that they cannot influence the overall quality. The combination of low writing speeds and the CLV writing technology seems to guarantee the quality results. Moreover, the Z-CLV technology adopted for 16x and 32x speeds does not affect the writing quality.

10. HS-RW Writing Tests

Duet CD-R2-U2 slim CD-RW/DVD combo - Page 10

HS-RW Writing Tests

We used Nero Burning Rom for writing CDs in the maximum RW speed supported by Duet LSC-24081. The drive supports 12x (Z-CLV) maximum rewriting speed. The other supported speeds are 10x, 8x and 4x, as you can see in the picture from Nero on the left.

The Duet LSC-24081 finished in 5:41 minutes, and needed 34 seconds to perform the "quick erase" task with Nero. The Incoder drive is slower since it supports 8x maximum CD-RW speed.

- Packet Writing Tests

We used InCD and Ricoh HS-RW media for all Packet Writing tests. The formatting of the media takes around 10min. The formatted disc had 530mbs of free space. We copied a 403 MB file (403.147kbs) from a Hard Disk (on the same PC as the writers) to the formatted RW media-using explorer (we dragged and dropped it). We completed the test twice to eliminate possible time measurement faults and user errors.

In the writing part, both drives gave the same average speed. Reading was faster for the Duet drive, with a 8.56x average speed.

11. Conclusion

Duet CD-R2-U2 slim CD-RW/DVD combo - Page 11


Positive (+)

Negative (-)

  • 24/12/24/8x CDRW/DVD combo drive
  • USB 2.0/1.1 supported interface
  • Small dimensions, light weight
  • Fast CD-R/RW/DVD-ROM reading
  • Low CD/DVD seek times
  • Supports DVD-R/RW, +R/RW, DVD-ROM formats
  • Good error correction performance with DVD discs
  • Good writing quality
  • 24x maximum DAE speed
  • Overburning up to 99min
  • Supports CD-Text (reading/writing)
  • Supports 99min discs
  • Incomplete retail package
  • Delicate CD tray
  • Average CD-R error correction capabilities
  • Low DVD-Video ripping speed
  • Does not support audio protected discs
  • Cannot create working SafeDisc v.2 backups
  • Z-CLV implementation leads to increased recording times

Duet LSC-24081 is a fast portable CD-RW/DVD-ROM combo drive, supporting fast and easy installation through the USB 2.0 interface. It is lightweight and of small dimensions.

The retail package could be better, since it does not include any blank CD-R or HS-RW media, or any DVD player software. Recording and packet writing applications are included, however, along with manuals and installation drivers.

As we said the small dimensions and the low weight of the drive make it a very handy solution for attaching it to your notebook or on your PC itself. What could be improved is the delicate structure of the CD tray, and the response of the eject button.

The Duet LSC-24081 supports the 24x Z-CLV maximum recording speed for the CD-R format. Our tests showed that the current implementation of the Z-CLV technology does not allow the drive to achieve the lowest writing times among the 24x category drives. However, the writing stability is very good and no writing problems occurred while writing on various media. In addition, the Jitter measurements on the recorded media showed a high writing quality. Overburning up to 99min is included among the advantages of the external drive.

In the reading part, the drive is fast and the reading speed reached the supported 24x, both using pressed and CD-R media. The seek times for the CD and DVD format is low, but the ability to correct possible faulty bits on defected and scratched media (Almedio Abex) could definitely be higher. The drive also retrieves C2 error information while reading.

The maximum supported DAE speed is 24x. The drive cannot handle Key2Audio and Cactus Data Shield 200 protected audio discs.

Reading of 96 bytes of SubChannel data is supported, as it is also the reading /writing of CD-Text on audio discs. In addition, the drive supports the 99min CDs.

CloneCD users will not be satisfied by the lack of the drive's ability to create working backups of the latest SafeDisc v.2 protected titles, although the reading speed is adequate.

As for the DVD format, the drive supports reading of DVD-ROM (single layer) at 8x CAV, and also supports reading of DVD-R/RW and DVD+R/RW discs at 4x-5x on the average. In addition, the DVD error correction tests with ABEX test media showed that the drive has no problems with scratched and defected DVD-ROM discs, giving accurate reading output. Ripping of DVD Video contents is a weakness of the drive, since it is very slow, giving an average ripping speed of 1.7x.

The suggested street price for Duet is about USD 180.

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