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 Post subject: the "pressing" of laserdiscs
PostPosted: 13 Sep 2020, 23:00 
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some time ago, i read: An approximate figure is 25,000 pressings from a single stamper before it needs to be retired.

What got me curious here, is: "What level of degradation in the stamper exists before retirement (if any)?"

Here's a "loose" analogy: Let's say you have a rubber stamper to stamp "PAID" on invoices in some kind of office setting. Eventually, the rubber wears down and the stamper doesn't stamp the word "PAID" as well.

Is 25,000 the amount of pressings before "any" degredation? Or is 25,000 the amount of of pressings before "acceptable" degredation?

Sometimes i've heard people say, "(such and such) movie looks great!". Then i get a copy, and it doesn't look so great (picture noise). Did they have #1-100 off the stamper and i had #24,999?
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 Post subject: Re: the "pressing" of laserdiscs
PostPosted: 13 Sep 2020, 23:20 
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I'm only guessing and going by what I saw on how to make CDs on a how its made episode.
I guess that the 25000 if there is such a number was figured out with microscopes or other devices to read data and make sure its
within the tolerance level.

When I saw the how its made the CDs were made without any real hands touching and it was all mechinical.
it was a great episode on how optic media was made.
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 Post subject: Re: the "pressing" of laserdiscs
PostPosted: 14 Sep 2020, 00:34 
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9954tony wrote:
Is 25,000 the amount of pressings before "any" degredation? Or is 25,000 the amount of of pressings before "acceptable" degredation?

Interesting question. I would think the latter. In either case, I don't think there would be any visual difference (in regards to playback).

9954tony wrote:
Sometimes i've heard people say, "(such and such) movie looks great!". Then i get a copy, and it doesn't look so great (picture noise). Did they have #1-100 off the stamper and i had #24,999?

As long as they are from the same master, the players involved and their adjustments will be the main factor. i.e. a LD-V2000 vs a CLD-D502 or even a CLD-97 vs a CLD-97 with the tilt servo improperly adjusted.

9954tony wrote:
I guess that the 25000 if there is such a number was figured out with microscopes or other devices to read data and make sure its within the tolerance level.

Yeah I think it was pretty much this. By the mid 1980's they had gotten this down to a very fine science.
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 Post subject: Re: the "pressing" of laserdiscs
PostPosted: 14 Sep 2020, 00:43 
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I don’t think your train of thought is correct. However LDs were made mostly the same way that CDs, and DVD, and every other optical disc is made so if you want to know more there has to be TONS of data on this.

Your example of a rubber stamp doesn’t take into account gain adjustment. A rubber stamp is “open loop” whereas the LD signal has ways of making itself immune to minor fluctuations in signal strength. The reason other people say certain discs are great and you don’t see it is because no two setups are the same. Actual LD viewing on one setup is impossible to duplicate on the other end. This why Youtube uploads and screen captures are nearly useless except for entertainment. People who have high end decks can’t even seen the horrendous red noise that comes with every disc played on an S201.
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 Post subject: Re: the "pressing" of laserdiscs
PostPosted: 14 Sep 2020, 02:03 
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I didn't make up the 25,000 figure, it was on the linked page: http://www.laserdiscarchive.co.uk/laser ... oduced.htm

signofzeta wrote:
I don’t think your train of thought is correct... ...Your example of a rubber stamp doesn’t take into account gain adjustment


The analogy was only with regard to the wearing of the mold/stamper. The mold/stamper wears out, otherwise they wouldn't need to change it after 25,000 uses. The fact that they change stamper/mold at all, indicates that there *is* a point at which the finished product would be noticeably degraded, they wouldn't waste money making more molds/stampers than they needed. My pondering was about that, and at what "acceptable" level they decided to set the limit, that's all.

Signal strength (the gain adjustment) isn't the only parameter, or the one i was thinking about, it would be imperfections affecting the frequency output that i was thinking of.

I'm also not the only one to have this thought:
"Suspected causes of snow in freshly minted discs include: pressing discs with a worn or damaged stamper, pressing when the acrylic is not at the correct temperature, peeling the stamper and acrylic apart too soon or too late, metallization layer too thin, and contaminants in the production environment." from http://www.blam1.com/laserdisc/FAQ/FAQ_Hardware.htm

Hopefully, it is as all of you say, and the replacement happens well before any noticeable degradation.
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 Post subject: Re: the "pressing" of laserdiscs
PostPosted: 14 Sep 2020, 03:57 
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9954tony wrote:
I didn't make up the 25,000 figure, it was on the linked page: http://www.laserdiscarchive.co.uk/laser ... oduced.htm

signofzeta wrote:
I don’t think your train of thought is correct... ...Your example of a rubber stamp doesn’t take into account gain adjustment



I read something similar for vinyl/records.

The master is supposed to be used up to 50K discs but factories on a budget will push them to 60K or 70K.
One reason why vintage Japanese records are still in demand: pure vinyl (no chemical mix in the 70's during the oil crisis to make them cheaper) and no overworn masters.

On Pioneer mint marks, it's easy to see which master you got:

XXXXXXX-A01-P YYYYYYYYY

That's master #1.

Late pressing rarely went up to #2.

Julien
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