Very interesting to read these posts, this is an area in which I have an interest (
@kensalriser 's 'excessive geekery') but also perhaps in which a little knowledge is a dangerous thing.
Let me clarify my understanding when making my original post. Each record title has one or more catalogue numbers (depending on releases, countries etc). Each physical disk also has a number in the deadwax which, like a 'batch code', can theoretically be used to establish which pressing plant and what date the record was physically made (together with a batch of, say 1000-10000 others). The deadwax numbers/batch codes are specific to the item and its manufacture. Earlier pressings are sometimes considered desirable, and because each matrix is unique to a batch, each physical disk within a batch is likely to be of similar quality to the others in the batch.
However some albums in different countries appear to share the same matrices. Using the UK first press of Abbey Road as an example, I don't have one (yet - thanks
@twotone but I'd probably prefer a NM or VG+ as my motivation is sound quality), but Discogs says the only numbers on the run-off (I take these to be the matrix numbers) are:
Matrix / Runout (Side A Run Out): YEX 749-2
Matrix / Runout (Side B Run Out): YEX 750-1
The Australian Abbey Road has identical ID numbers (though different catalogue numbers).
I'm assuming (maybe wrongly,
@Vinny) that these numbers link the production of the record to a time and a place and as the numbers are the same, to the same time and place. How can the number associated with the UK first pressing (associated with first pressing from presumably a UK plant) also be on the Australian disk? I'm guessing either the records were exported to Australia (with a different catalogue number), having been made in the UK at the same time as the UK run for the Australian market or, as
@mondie says, the machines were moved out there later. If the matrix numbers are the same and show a link to production machinery, the machines would have to be the same machine, moved to Oz, hence there is a belief that the Ozzy version (in this case) might be a cost effective of getting the quality associated with a UK first pressing. If it was a different stamper (from the same mother/metal/whatever) it would have a different number, and the presumed uniformity in quality (as claimed because the UK first pressing and Australian disk have the same matrices) is gone (which means the suggestion of buying a cheaper UK first pressing by the back door is erroneous). If these are not matrix numbers at all, of course all bets are off, though in this case Abbey Road's first pressing would appear to have no matrix number.
By the way
@Big Tabs I feel your pain with that long line of numbers and trying to find the first pressing. I have experienced the same. And while 'look on Discogs' is fair enough, sometimes it's not that easy. In that regard, can someone confirm my Noddy assumption that when you click on (eg) a UK release and 35 copies of a vinyl LP come up, pressings are chronological, so the first pressing is top left (there might be variants within that, as in the Hounds of Hell example), and you would read left to right and then downwards for subsequent pressings, until you find the most recent at the bottom right corner?