Quote Originally Posted by Ali Tait View Post
It'll tell you if you are buying tired valves being sold as NOS though.
Not necessarily. Valves that meet minimum manufacturers standard were sold as new. Say they degrade 30% and now test at 70% they will be hovering around the replace mark. New valves that measured much better than manufacturers spec that were sold new, lost 30% of emmission, can still measure well above that minimum spec, so even though they are far from new and arguably sonically tired they will measure as or better than minimum manufacturers standard. That is why this spec, now often taken as a litmus for NOS condition, is really not.
However I do agree that a valve that measures poorly cannot be to minimum manufacturers standard and so cannot be NOS in any rational sense unless new old reject stock and should definitely be avoided...
I hope this helps some who find the world of valves confusing [emoji2]