Lite-ON SHM-165P6s or DH-20A4P?

I need a good drive only for media scans.
I’ve this two drives but I don’t know wich one of them are better for make scans of DVD media recorded quality.
Someone can HELP me?


P.S.: Better Nero CD/DVD Speed or OptiDrive Control?


Interesting that you should mention those two drives. The DH-20A4P has been my standard DVD scanning drive for many years, ever since I bought my first one. But the SHM-165P6S is still what I consider to be my reference drive.

The short answer is that they are both very good DVD scanners and either would be a good buy. Personally I would try to buy both drives, especially if they are new old stock (or ridiculously cheap secondhand drives in good working order). But if they are secondhand and you can only buy one then I would be inclined to get the DH-20A4P as it is slightly newer. If they are new and you can only buy one, it’s a tricky decision - they’re both good scanners, slightly different but good. In that scenario I would probably get the SHM-165P6S, but only because I know that the DH-20A4P is such a common drive on the secondhand or nearly new market. The DH-20A4P is probably a better drive if you wish to scan at 8x speed rather than 4x, but it has its downside as well.

Both are also excellent DVD writers. The DH-20A4P probably has the edge when it comes to writing modern discs of mediocre quality, but the SHM-165P6S probably has a slight advantage when it comes to the best quality discs.

The only areas where one drive is definitively better than the other is when it comes to DVD-RAM discs (reading as well as writing) and writing CD-R discs. The SHM-165P6S has a serious bug when it comes to handling DVD-RAM discs, which can render them completely unusable. It also comes from the period when Lite-On drivers were notorious for high jitter when writing CD-R discs. The DH-20A4P has no such problems and is a decent CD writer.

As for software, I still prefer good old CD-DVD Speed. Not only is it free, but it is less buggy than Opti Drive Control. I generally only use Opti Drive control for Blu-Ray scanning or with my Plextor drives as an alternative to PlexTools. Although it is newer than CD-DVD Speed (or Plextools), it doesn’t seem to run as well on Windows 8.x or 10 - getting it to scan at the selected speed is a particular problem.

[Optional: If you want the long answer, read on]

The DH-20A4P is a very good drive. It can scan consistently at 8x speed as well as 4x (the traditional standard scanning speed for Lite-On drives) and it stabilises the speed reliably before scanning begins. [Some drives, such as the almost identical LH/DH-20A1 series adjust the speed just as scanning begins which produces elevated errors at the start of discs.]

The only problem with the DH-20A4P is that it drops more samples than I would like. If you look at the statistics window show at the end of the CD-DVD Speed disc quality test it shows the average scanning interval. For a Lite-On DVD scan this should ideally be 1.00 ECC, but my DH-20A4P drives consistently score ~1.20 ECC at 4x speed and >1.30 ECC at 8x speed (indicating that samples have been lost or skipped). This should be perfectly acceptable and nothing to be particularly concerned about, unless you’re an old-fashioned CDFreak who known that some of the 60+ other drives in your collection can consistently scan at 1.00-1.02 ECC. :givewink:

At this point I should emphasise that you are highly unlikely to ever be able to see the difference between a 1.20 ECC scan and a 1.00 ECC scan - the difference would almost certainly be less than you would see by scanning the same disc twice in the same drive. [However it appears to explain why my Lite-On Blu-Ray writers, which show an average scanning interval of ~2.00 instead of the expected 1.00, always reports PIE error levels half that of a Lite-On DVD writer.]

My SHM-165P6S was a drive I absolutely loathed when I first got it, but it received some major firmware updates which transformed it into one of the all-time classics (for DVD±R/RW, but not DVD-RAM or CD-R). It can scan at 4x with a low average scanning interval (typically 1.02, IIRC). At the time 8x scanning was considered too fast for reliable results with Lite-On drives (the results tended to emphasise the reading ability of the drive more than the quality of the disc). But the SHM-165P6S was one the first Lite-On drives which could produce useful scans at 8x speed. My own experience was that on good quality discs the results would be similar to a 4x scan. On mediocre discs the error averages would often be elevated, but it was good enough to be useful at 8x - any suspect discs would be rescanned at 4x, but if the result at 8x looked good I was satisfied that the result could be trusted.

The reason it is still my reference DVD scanner is partly because it was the first drive I had which produced consistent results I could trust and partly because of where it fits in the DVD writer family tree. I class it as Lite-On’s first ‘second phase’ 16x drive - my own designation for the first drives which (in my opinion) could be considered fully developed DVD writers. (The boundary is around late 2005, but the exact date varies by manufacturer - NEC’s drives actually went dramatically downhill at this point.) To be a useful scanner (that is one which can reliably allow one to differentiate between a ‘good’ disc and a ‘bad’ one) one needs a drive which is not only consistent, but is fairly representative of the reading ability of a typical drive. Newer drives were generally better at reading discs than older models, so would report fewer errors. DVD-ROM drives (especially those in DVD video players) on the other hand are almost invariably worse at reading discs than writers. For me the SHM-165P6S is a good balance. At 4x speed it produces consistent results which are similar to those from later drives, but I am confident that it will allow me to identify discs which are likely to have playback problems on other drives in the future - which after all is the whole point of disc scanning.

But then again my DH-20A4P drives have proven to be equally good in that respect. So I use one of those (the external version) as my main day-to-day DVD scanning drive. The SHM-165P6S is brought out to offer its opinion on the very rare occasion that I get a result that I am doubtful of, or when I want to evaluate some very special discs.

Take you pick (or buy both if you can afford to :givewink:), then have hours of fun scanning with your new drive. :biggrin:

Hello, many thanks for your time.
I’ve the two drives, but i remember that 20a4p was new when i buyed.
The other one was second hand.
I use scan my burned DVD @1x usually,because i think that results are with more accuracy.
4x or 8x scans give me more errors in PIE and PIF results.
Nero CD/DVD Speed give me always a trouble when scan DVD+/-R DL:
Software never end scan!!!
I don’t understand why this trouble.
Then, dual layer DVD need to scan with Opti software.
This was when i use 20A4P drive.
Do you know why?

More thanks.

And sorry for my bad english.


Which version of CD-DVD Speed are you using? The final free version was v4.7.7.16.

[There is also an unofficial ‘SE3’ version of v4.7.7.16 available on this forum which was modified to support jitter reporting with the later Lite-On drives - from the 20A3 onwards. The 20A4P uses the same chip as the 20A1P and will work fine with the unmodified version. But if you use the modified version then jitter will not be reported.]

I rarely use DL DVDs - I think my lifetime burn count stands at 2x MKM003!! The last one I wrote was almost a year ago. I checked the scan and the only issue was that it could not report jitter for the second layer. I don’t recall whether or not it stopped of its own accord or if I had to stop it manually; the fact that I was able to save the statistics window suggest that the scan probably ended automatically.

There are a lot of factors which can interfere with scanning discs, including other software on the computer (especially decryption tools such as AnyDVD), proprietary device drivers for the IDE or SATA interface and even the interface hardware itself. Troubleshooting these problems can be a nightmare.

What brand & media code of disc are you using? Poor quality discs can cause the scanning drive to become stuck and not complete. Disc quality is much more critical for DL discs than SL, and some drives never seemed to write DL discs properly at all. The only DVD+R DL discs with a good reputation are those made by Verbatim/MKM and Falcon, and even those can have bad batches. Anything else is a lottery and the disc itself should be the first suspect in the event of problems.

4x scanning speed should be fine. (Whether reading/scanning or writing, slower speeds are not necessarily better.) If you are seeing a significant difference in errors between 1x & 4x scans then I would suspect the quality of the discs.

Changing the scanning speed doesn’t affect the accuracy as such (apart from possibly increasing the number of dropped samples). What it is doing is changing the read behaviour of the scanning drive. The errors which are recorded on the scan are not features on the disc, but events experienced by the drive while reading/scanning the disc. When changing the speed or using a different drive affects the number of errors recorded in the scan, it is not because errors or defects on the disc have been missed (apart from dropped samples) but because the drive encountered fewer error correction events when reading the disc that time. Even the best scanning drives will produce slightly different results every time they scan the same disc, even at the same speed.

I use the same Nero CD/DVD Speed like your.
I also use Verbatim DL discs, but tried Moser Baer, Ricoh, Ritek and many more that are very low quality.
I use a Pioneer DVR-219L to write DL discs and it’s the best drive to do it.
From a year ago i use only ImgBurn to burn DVD.
I use a LG GSA-4163B ide plugged sata with an adaptator and i surprised by it’s very good quality of burning DVD.
I have a lot of burner: Many Plextor PX-760A; Plextor PX-800A (Optiarc); 6 different Lite-On, a lot of Nec Optiarc, 1 old Panasonic Panasonic SW-9573-C and 1 Panasonic SW-9586-C.
I don’t remember other burners that i’ve, like Pioneer and many other.
Good media that i’ve are Taiyo Yuden (JVC) DVD-R 8x, Sony DADC Professional DVD-R 16x, first edition Verbatim DVD-R 16x, first Verbatim ever made DVD-R 1x For General, Memorex CMG DVD-R 4x and many other.

Now i’ve a Lite-On DH-16AASH15B sata drive but i don’t know it if is a good burner/scanner.
Do you know it?
At last, I’ve a very old Waitec Action/8 (Lite-On) ide burner but i don’t love it.
I flashed firmware and now it’s a Lite-On LDW-851S.
Sure that you know it.



P.S.: If you want, i can send you my scans.