Re: [AV Media Matters] medialine CD-R permanence article

[pomeroyaudio@att.net]

Thanks for info.
The news about phthylocaynine is very
significant, because it means all audio
must first be loaded onto a hard disk,
and this will have a huge impact on
those doing archival work!
(I'm going on vacation tomorrow, and
will be unsubscribed for one week.)
--
Doug Pomeroy   pomeroyaudio@att.net
Audio Restoration [CEDAR] & Remastering

Moderators Comment:
Again - PLEASE read my posting regarding the elimination of
unnecessary verbatim quotations as seen below. And Doug has given me
a perfect opportinity to remind those going on vacation to please
use the "vacation" feature if you choose to suspend delivery of
Listserve emails. But whatever you do  - PLEASE do NOT use
autoreply. Thank you.

james

>From: mickelmor@yahoo.com
>To: AV Media Matters <AV-Media-Matters@topica.com>
>Subject: RE: [AV Media Matters] medialine CD-R permanence article
>Date: Mon, Mar 12, 2001, 9:48 AM

>hello
>
>i'm the news editor for medialine. doug, thanks for
>the props.
>
>last month's article on cd-r permanence will be up on
>the medialinenews.com website next week. in the
>meantime, anyone interested in an electronic or
>physical copy of the article and related info can
>email me at tkeegan@uemedia.com.
>
>for anyone who has seen the article already, we're
>publishing in our next issue a letter we received from
>mastering engineer kris solem of hollywood, ca-based
>future disc systems, which reads as follows:
>
>"Thank you for publishing Jacob Trock's interesting
>and important article: 'How Permanent is CD-R Media?'
>(Medialine, February 2001, page 39).
>
>"I have one question regarding his conclusion,
>'writing speed is a problem with pthalocyanine
>discs--illustrated by the increase of BLER from the
>inner to the outer part of the disc, where the
>rotational speed slows down from 600rpm to 230rpm.'
>
>"As I understand it, the rotational speed of a compact
>disc is constantly adjusted to maintain a fixed linear
>speed at which the data track passes the laser,
>regardless of where the laser is along the radius of
>the disc. This *Constant Linear Velocity* ensures that
>the writing and reading speed do not change from the
>inside to the outside of the disc. Conversely,
>*Constant Angular Velocity* maintains a constant
>rotational speed (rpm's).
>
>"In this situation, as the pickup device (laser, head,
>needle, etc.) moves to the center of the disc, the
>slower is the actual linear velocity of the track
>moving past. Remember the vinyl LP, where the sound
>quality deteriorates toward the inside of the disc for
>this exact reason. Also, computer hard disks, which
>spin at a fixed rate, pack data more densely at the
>inside of the disc because adjusting the rotational
>speed would cause slower access times during random
>access operations. If BLER is increasing toward the
>outside of the pthalocyanine disc, some factor other
>than writing speed must be the cause."
>
>to date, i have not heard a response on this qustion
>from jacob trock, who wrote the article.
>
>terence keegan, medialine
>
>
> --- pomeroyaudio@att.net wrote:
>>
>>Medialine magazine dated Feb 2001 carries (on p 39)
>>a very interesting article titled "How Permanent Is
>>CD-R Media?", written by Jacob Trock of the School of Conservation in
>> Copenhagen. The testing company involved is AudioDev (www.audiodev.com).
>> The article may eventually - in a few weeks -  be viewable on
>> the magazine's web site (www.medialinenews.com).
>>
>> Highly recommended to those who really want the truth and
>> are willing to deal with less than simplistic answers.
>> (But, the results reported indicate we should now definitely
>> avoid ever writing phthalocyanine dye discs at 1X speed.)
>>
>> Doug Pomeroy   pomeroyaudio@att.net
>> Audio Restoration [CEDAR] & Remastering