Just an observation, I've got old (like many years old) broken in flats on one 34" FSO. I just put the exact same brand and gauge on another 34" scale FSO. The brand new ones feel stiffer than the well-worn ones, which feel "softer" and a bit more flexible, i.e. lower tension(if only slightly). I haven't necessarily noticed this all the time when changing strings on various basses, and it could be all in my head, but I figure it's fairly safe to assume that as strings break in over time and stretch, they would "give" a bit which would actually relax some tension, no?
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