jj tubes?

I read that the jj e34l tubes tighten up the bass. Subsequently also the ecc83 s. I know a few you guys have these tubes and wonder just how much of an improvement...ie minor or major? Especially from those who own stilettos...

thanks.

I just put two of them for sockets 2,3 in my dual rectifier and they certainly do tighten up the bass. I think it's a pretty significant change in tone because your amp isn't mushy at all, especially in the spongy variac/tube recto. It sounds like that nice fat purr/grind that made the DR famous. I think the most difference is in the 2nd channel in the vintage (voice of the recto) setting, it sounds much tighter and punchier with a heavy crunch.