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In Reply to: Re: Greater weight of dual discs posted by Martin419 on November 11, 2005 at 02:31:10:
>>In any case, the max thickness of DualDisc is <1.5mm, which is inside Redbook CD spec. So if a CD can be 1.5mm thick, then the proportional weight of the polycarbonate has to be in spec too.<<In the interest of controversy, I just performed an experiment. I used a precision electronic scale (a Jadever JKD-250) that is accurate to 0.05g, and weighed a bunch of discs randomly pulled out of my collection. The scale was calibrated with a calibration weight. I weighed each disc 3 times to be sure of accuracy. I'll caveat this by saying that since I don't own any DualDiscs, I had to borrow one from a neighbor, so the sample range isn't as wide as it should be; therefore, I will not call this experiment "scientific," merely interesting. :-)
Disc - Format - Weight(in grams) - Comment
Kraftwerk: Tour de France - CD - 14.80 - Redbook CD released 2003
e-Nomine: Die Prophezeiung - SACD - 14.30
Pink Floyd: DSOTM - SACD - 16.65
Tangerine Dream: Cyclone - CD - 16.75 - Redbook CD manufactured 1985
Nine Inch Nails: With Teeth - DualDisc - 19.25
OST: You Only Live Twice - CD - 14.95
Coltrane: Blue Train - HDAD - 16.45
Metheny: Imaginary Day - DVD-A - 16.90
Berloiz: Requiem - SACD - 16.30 - RCA Living Stereo Disc 1 of 2
Berloiz: Requiem - SACD - 16.30 - RCA Living Stereo Disc 2 of 2
Mickey Hart: Over the Edge - DVD-A - 16.70
Stanley Clarke: If this bass... - CD - 16.05 - Redbook CD manufactured mid-'90s
Herbert Grönemeyer: Bleibt Alles Anders - CD - 15.40
Alan Parsons Project: Turn of a... - HDAD - 16.65
Herbert Grönemeyer: Stand Der Dinge - DVDplus - 20.60 - Disc 1 of 2
Herbert Grönemeyer: Stand Der Dinge - DVDplus - 20.30 - Disc 2 of 2Lightest CD - 14.80 (Kraftwerk)
Heaviest CD - 16.75 (Tangerine Dream - early Redbook)Lightest SACD - 14.30 (e-Nomine)
Heaviest SACD - 16.65 (DSOTM)Lightest DVD-A - 16.70 (Hart)
Heaviest DVD-A - 16.90 (Metheny)All SACDs weighed are hybrids.
The 1985-manufacture Tangerine Dream Redbook appears to be thicker than most later-manufacture CDs.
HDADs are dual-sided DVDs, weight is consistent with CDs, DVD-As and SACDs.
DVDplus is a structure similar to DualDisc - dual-sided, with DVD on one side, CD on the other. The DVDplus discs I have are early DVDplus (circa 2000), and they are substantially thicker than anything else (approx 1.8mm), so it's no surpise they are heavy. The heaviest DVDplus is 19% heavier than the heaviest CD, and 18% heavier than the heaviest DVD-A. The latest version of DVDplus is supposed to be thinner and lighter.
The DualDisc is new-manufacture. I did not measure its thickness, but it is interesting that it is notably heavier than all the other "standard-format" discs. Only the DVDplus discs are heavier (by 7%).
The DualDisc is 13% heavier than the heaviest CD, 23% heavier than the lightest CD.
The DualDisc is 10% heavier than the heaviest DVD-A, 13% heavier than the lightest DVD-A. It's also interesting to note that the HDADs are slightly lighter than the lightest DVD-A.
The DualDisc is 14% heavier than the heaviest SACD, 26% (!!!!) heavier than the lightest SACD.
So, this one DualDisc I was able to obtain does not fit into your supposition, Martin. If it is a representative sample (and I have no reason to believe it is not), then DualDiscs are not in proportion from a weight standpoint. They are substantially heavier.
Follow Ups:
I did some additional digging, and found that the ECMA standard for the mass of a DVD disc is 13g to 20g. The bulk of the DVD discs I weighed fall right in the middle of that range, as should be expected. The DualDisc, at 19.25g, is within the standard; however, it shows that once again DualDisc pushes to the outer edge of tolerance. DualDiscs are at or near maximum allowable thickness, and it appears that they are also at or near maximum allowable weight.Will this cause a problem? Cheerleaders say no, haters say yes. I say: I don't know.
> > Will this cause a problem? < <
> > If it is a representative sample (and I have no reason to believe it is not), then DualDiscs are not in proportion from a weight standpoint. They are substantially heavier. < <What I said was that if Rebook CD spec allows for a disc that is "1.5mm" thick, then the proportional weight of polycarbonate must be in spec too.
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