Isochronism...I rarely changed guitar amp tubes. Unless something started sounding strange or blew up (VERY rare) I blasted through various Twin Reverbs, my white Bandmaster head, and whatever Boogie/Marshall/Hiwatt I had. Maybe because I couldn't SEE the tubes or something I just forgot about them. I assume some guitar players back then cared about such things like I do now, but there seemed to be 2 tube types: New ones and the old tubes you almost never replaced...now with my groovy "boutique" little tube guitar amps I get the urge to roll tubes in them out of curiosity, like an idiot. I think I was better off not giving a crap.
