New KT150 tubes?

Wow great price Wolf. But sue to write how they sound especially compared to the KT120's.

Wolf_ whilst In no way insinuating you to be a Numb Nutz....around valve gear, however, i'd be inclined to back the bias right off of the incumbent valves, insert the 150's, then steadily increase bias back to to circuit spec or close to on the conservative side for a while.

I've been using tube amps since about 1962 (albeit that was my cousin's white Bandmaster guitar amp), and anytime my Nutz get into a thread, well, it's a good thing...note that with all of those tube guitar amps nobody cared one bit about warm up or bias...we silly kids had no idea what bias was (I assume the repair dudes did). In any case, I've swapped the tubes out of my Jolida plenty and always turn the bias WAY down...after dialing the bias back and sticking new tubes in (and looking out for explosions or large flames) I wait a while and reset it, then check it again hours later...most tubes seem to stay in bias fairly well after the first warmup tweak, but I'm a serial tube finger burning bias freak anyway so I'll be poking it with my meter probes willy nilly.

Happy to report that the 150s are great...not unlike the 120s initial impression of effortless expansion of the whole frequency spectrum, and it seems the amp is a little louder, although that could be my imagination...little more heat but no biggie, bias is even and holding fine (after initially biasing them to the 500mv amp specs, all of the tubes were up 50mv when I re-set them later, no clue why but at least they were even!). My only criticism is that there's less filament glow like my newly installed "hidden filament" GL 12AX7s...I want more glow damnit, but will learn to live with it somehow...at least my Mullard 12AT7s look alive...

@ David12, I'm curious as to whether you attended the GS series soirée at KJW1 this weekend past?