On 11/02/2013, Tom Fine wrote:

> One story I'd love some science applied to that's related to this --
> are there _really_ any differences between BMG Music Club CDs and the
> original issue CDs? I've read several things over the years stating
> that BMG Music Club versions of Mercury CDs sounded "inferior." But
> the few BMG versions I have are bit-perfect replicas of the originals,
> so the bits is the bits. What else could be "wrong"? Did anyone ever
> do any tests to compare baked-in jitter for both discs, assuming BMG
> even used a different glass master?
> 
> I'm also mystified by recent reviewer statements that the new box set
> CDs sound "better" than the originals (they sound the same to my
> ears), but in those cases, with all the pre-1998 catalog numbers, they
> are indeed using parts made from different glass masters from the US
> originals. The reason was, US production was done at Philips-DuPont in
> North Carolina and everything else was done at Polygram in Hanover
> Germany. Today, everything is done in Hanover, using the Hanover
> manufacturing parts. The other difference I've suggested to reviewers
> is mechanical playback. The original US CDs had shiny/slippery cores
> around the spindle hole. Modern CDs are somewhat rough and also are
> lighter net weight (by an ounce or more, according to my scale). So
> they might present fewer mechanical problems for a player, at least
> that's my theory (ie they get gripped harder because of the rough
> surface and spin easier because they weigh less).
> 
I had an early player on which, if you ripped a CD to a CD-ROM, the copy
sounded better than the original. 

I think this was because the copy disc was lighter. The designer
underestimated how much power was needed to spin the discs. The result
was a drop in voltage supply to the audio output circuit. (In my
opinion.)

Regards
-- 
Don Cox
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