I think there are a couple of reasons your new copy sounds superior - it's stamped on heavier, better grade vinyl, and it's not suffering from 38 years of wear and tear.

My own (stereo) copy still sounds great, with smooth bass, clear vocals and crisp drums. So does "Jefferson Airplane Takes Off", although that was an Italian import when I bought it in the 70's, and may have been a better quality pressing.
-=LC=-