Why do most test pressings that I've heard sound better than a bought-in-store version of the LP?
Did the plants do something special for the test pressing or use a "brewer's choice" biscuit
compound or is it more a random chance of having a further-down-the-production-run copy in a store
and thus worn stampers? Where I've been able to compare a master laquer to a test pressing to a
bought-in-store version of the same cut/matrix/whatever, the test pressing usually sounds pretty
darn close to the first cut but the production disk sounds inferior, usually lower s/n ratio and
noisier surface. This was less true in the one case I've been able to compare all 3 for a modern LP
reissue and I assume it's because a modern reissue that appears at retail will be pressed with more
care on better vinyl and fewer copies will be made per stamper, but I might be wrong on that.
In some older examples, late 50's and early 60's, the retail version vinyl seems to definitely be a
different compound from the test pressing, which more resembles modern, "softer" quieter-playing
-- Tom Fine