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When DVD burners got to 16x I thought that would be the limit but was
surprised to find that Lite-On and Benq have 20x models: Benq DW2000
http://www.benq.com/products/Storage/?product=1017 and Lite-on
LH-20A1H (with Litescribe) and LH-20A1P http://tinyurl.com/y6h5j4 .

specs for the LH-20A1H:

DVD+R 20X maximum by CAV
DVD-R 20X maximum by CAV
DVD+R9 8X maximum by Zone CLV
DVD-R9 8X maximum by Zone CLV
DVD-RAM 12X maximum by PCAV

ReWrite
DVD+RW 8X by Z-CLV
DVD-RW 6X CLV

Read 16X maximum by CAV
Access time 160ms

CD Family
Write
CD-R 48X by CAV

ReWrite
CD-RW 32X maximum by Z-CLV in UltraSpeed disc
Read 48X(7200KB/sec) maximum by CAV

One thing I find slightly curious, comparing against the 18x version
which seems identical except for the top burning speed is that the 20x
version doesn't list 98SE in the compatible operating systems.
Perhaps an unintentional omission?

Now lets see if Woger says these are obsolete.

"GraB" <> wrote in message
news:...
> When DVD burners got to 16x I thought that would be the limit but was
> surprised to find that Lite-On and Benq have 20x models: Benq DW2000
> http://www.benq.com/products/Storage/?product=1017 and Lite-on
> LH-20A1H (with Litescribe) and LH-20A1P http://tinyurl.com/y6h5j4 .
>
> specs for the LH-20A1H:
>
> DVD+R 20X maximum by CAV
> DVD-R 20X maximum by CAV
> DVD+R9 8X maximum by Zone CLV
> DVD-R9 8X maximum by Zone CLV
> DVD-RAM 12X maximum by PCAV
>
> ReWrite
> DVD+RW 8X by Z-CLV
> DVD-RW 6X CLV
>
> Read 16X maximum by CAV
> Access time 160ms
>
> CD Family
> Write
> CD-R 48X by CAV
>
> ReWrite
> CD-RW 32X maximum by Z-CLV in UltraSpeed disc
> Read 48X(7200KB/sec) maximum by CAV
>
> One thing I find slightly curious, comparing against the 18x version
> which seems identical except for the top burning speed is that the 20x
> version doesn't list 98SE in the compatible operating systems.
> Perhaps an unintentional omission?
>
> Now lets see if Woger says these are obsolete.
>
>


why did you think 16x was the limit? Surely the limit is determined by
ability of the disc to withstand high rotational speeds. i recall some
stories of cd media fragmenting at 52x.

On Wed, 10 Jan 2007 09:54:01 +1300, "whome" <> wrote:

>
>"GraB" <> wrote in message
>news:.. .
>> When DVD burners got to 16x I thought that would be the limit but was
>> surprised to find that Lite-On and Benq have 20x models: Benq DW2000
>> http://www.benq.com/products/Storage/?product=1017 and Lite-on
>> LH-20A1H (with Litescribe) and LH-20A1P http://tinyurl.com/y6h5j4 .
>>
>> specs for the LH-20A1H:
>>
>> DVD+R 20X maximum by CAV
>> DVD-R 20X maximum by CAV
>> DVD+R9 8X maximum by Zone CLV
>> DVD-R9 8X maximum by Zone CLV
>> DVD-RAM 12X maximum by PCAV
>>
>> ReWrite
>> DVD+RW 8X by Z-CLV
>> DVD-RW 6X CLV
>>
>> Read 16X maximum by CAV
>> Access time 160ms
>>
>> CD Family
>> Write
>> CD-R 48X by CAV
>>
>> ReWrite
>> CD-RW 32X maximum by Z-CLV in UltraSpeed disc
>> Read 48X(7200KB/sec) maximum by CAV
>>
>> One thing I find slightly curious, comparing against the 18x version
>> which seems identical except for the top burning speed is that the 20x
>> version doesn't list 98SE in the compatible operating systems.
>> Perhaps an unintentional omission?
>>
>> Now lets see if Woger says these are obsolete.
>>
>
>why did you think 16x was the limit? Surely the limit is determined by
>ability of the disc to withstand high rotational speeds. i recall some
>stories of cd media fragmenting at 52x.
>

http://www.hitachi.com/New/cnews/040422.html

"The maximum rotation speed for a disc, without centrifugal force
causing disc burst, is about 16-times (16x) that of standard DVD
speed."

GraB wrote:
>> why did you think 16x was the limit? Surely the limit is determined by
>> ability of the disc to withstand high rotational speeds. i recall some
>> stories of cd media fragmenting at 52x.
>>
>
> http://www.hitachi.com/New/cnews/040422.html
>
> "The maximum rotation speed for a disc, without centrifugal force
> causing disc burst, is about 16-times (16x) that of standard DVD
> speed."

Its not 20 times single speed at its fastest, it will be much less then
that, and it will only achieve 20 speed at the outer edge. Thats why
they use constant angular velocity.

"GraB" <> wrote in message
news:...
> On Wed, 10 Jan 2007 09:54:01 +1300, "whome" <> wrote:
>
>>
>>"GraB" <> wrote in message
>>news:. ..
>>> When DVD burners got to 16x I thought that would be the limit but was
>>> surprised to find that Lite-On and Benq have 20x models: Benq DW2000
>>> http://www.benq.com/products/Storage/?product=1017 and Lite-on
>>> LH-20A1H (with Litescribe) and LH-20A1P http://tinyurl.com/y6h5j4 .
>>>
>>> specs for the LH-20A1H:
>>>
>>> DVD+R 20X maximum by CAV
>>> DVD-R 20X maximum by CAV
>>> DVD+R9 8X maximum by Zone CLV
>>> DVD-R9 8X maximum by Zone CLV
>>> DVD-RAM 12X maximum by PCAV
>>>
>>> ReWrite
>>> DVD+RW 8X by Z-CLV
>>> DVD-RW 6X CLV
>>>
>>> Read 16X maximum by CAV
>>> Access time 160ms
>>>
>>> CD Family
>>> Write
>>> CD-R 48X by CAV
>>>
>>> ReWrite
>>> CD-RW 32X maximum by Z-CLV in UltraSpeed disc
>>> Read 48X(7200KB/sec) maximum by CAV
>>>
>>> One thing I find slightly curious, comparing against the 18x version
>>> which seems identical except for the top burning speed is that the 20x
>>> version doesn't list 98SE in the compatible operating systems.
>>> Perhaps an unintentional omission?
>>>
>>> Now lets see if Woger says these are obsolete.
>>>
>>
>>why did you think 16x was the limit? Surely the limit is determined by
>>ability of the disc to withstand high rotational speeds. i recall some
>>stories of cd media fragmenting at 52x.
>>
>
> http://www.hitachi.com/New/cnews/040422.html
>
> "The maximum rotation speed for a disc, without centrifugal force
> causing disc burst, is about 16-times (16x) that of standard DVD
> speed."
>
>

he he, a good guess by me then.

In article <>,
Blue <> wrote:
>
>Somewhere along the line the idea that a disk wpuld break at x RPM was
>lost.

In true geek tradition, someone did some actual tests:

http://www.paintbug.com/cdexplode/

In summary, a "52x" CDROM drive reaches about 10,400 RPM, maybe more if it
tries to maintain the 52x data rate on the inner tracks of the disc. If it
was truly a 52x drive for all tracks of the disc, it would reach over 27,500
RPM on the innermost track and the disc would almost certainly explode. Even
assuming a maximum of 10,400 RPM, all it would take would be a slight crack
in the disc hub (such as that caused by a tight CD case spigot) for the disc
to shatter. It certainly explains the occasional "exploding disc" reports,
with bits of disc often breaking through the drive drawer front and shooting
around the room.

--
Don Hills (dmhills at attglobaldotnet) Wellington, New Zealand
"New interface closely resembles Presentation Manager,
preparing you for the wonders of OS/2!"
-- Advertisement on the box for Microsoft Windows 2.11 for 286

Don Hills wrote:
> In article <>,
> Blue <> wrote:
>> Somewhere along the line the idea that a disk wpuld break at x RPM was
>> lost.
>
> In true geek tradition, someone did some actual tests:
>
> http://www.paintbug.com/cdexplode/
>
> In summary, a "52x" CDROM drive reaches about 10,400 RPM, maybe more if it
> tries to maintain the 52x data rate on the inner tracks of the disc. If it
> was truly a 52x drive for all tracks of the disc, it would reach over 27,500
> RPM on the innermost track and the disc would almost certainly explode. Even
> assuming a maximum of 10,400 RPM, all it would take would be a slight crack
> in the disc hub (such as that caused by a tight CD case spigot) for the disc
> to shatter. It certainly explains the occasional "exploding disc" reports,
> with bits of disc often breaking through the drive drawer front and shooting
> around the room.
>

Mythbusters did this, they could reliably explode any disc they tried at
(IIRC) 19,000rpm

This wasn't really science (seldom is) and they clamped the disc to a
spindle similar to an angle grinder hub. Failure was spectacular, but
also of interest (perhaps because of the clamping system they used) was
the huge amount of deflection caused by a standing wave on the disk edge
itself - easily looked like >10mm, and maybe as much as 20mm. Pity they
didn't follow up on that detail - since CDs aren't *that* flexible, it
indicated that the failure mode might have been different to failure in
a normal drive.

On Wed, 10 Jan 2007 16:22:41 +1300, GraB wrote:

>
> http://www.hitachi.com/New/cnews/040422.html
>
> "The maximum rotation speed for a disc, without centrifugal force
> causing disc burst, is about 16-times (16x) that of standard DVD
> speed."

Remember that 1x CD speed is not the same as 1x DVD speed.

Then we have the point that the data is read/written at a constant linear
speed. So slower at the end (edge) of the disk.

Somewhere along the line the idea that a disk wpuld break at x RPM was
lost.

In article <>, -=rjh=- <> wrote:
>
>This wasn't really science (seldom is) and they clamped the disc to a
>spindle similar to an angle grinder hub. Failure was spectacular, but
>also of interest (perhaps because of the clamping system they used) was
>the huge amount of deflection caused by a standing wave on the disk edge
>itself - easily looked like >10mm, and maybe as much as 20mm. Pity they
>didn't follow up on that detail - since CDs aren't *that* flexible, it
>indicated that the failure mode might have been different to failure in
>a normal drive.

The Atlas Copco guys appeared to go to a lot of trouble to ensure accurate
disc clamping and a high-quality drive, and they didn't mention any unusual
bending modes. The Mythbusters might bave had problems with play in the
driveshaft which would cause what is colloquially known as "whirling", where
a shaft tries to rotate around a different axis than the one it is supposed
to at high RPM. As you say, it would explain why the Mythbusters' failure
point was 19,000 odd RPM against the Atlas Copco people's failure point
of 27,500 odd RPM.

--
Don Hills (dmhills at attglobaldotnet) Wellington, New Zealand
"New interface closely resembles Presentation Manager,
preparing you for the wonders of OS/2!"
-- Advertisement on the box for Microsoft Windows 2.11 for 286