"Just thought I'd mention that the Groove Tube GE-6L6GC replica I recommended is quite different from anything else out there at the minute. It's one of GT's USA-made valves along with their 6CA7.
GT list the GE-repro as 90% made in USA which suggests that all the internals are USA-made and the assembly is outsourced to Russia or China. This fits in with what I've heard on the grapevine about these valves being assemled in the far-East using USA parts...
http://www.groovetubes.com/assets/1713_GT6L6GE%20PR%204_02.pdf"
From what I understand the GT GE-repro 6L6 uses NOS parts (plate material etc) that was made in the US, and is then assembled in China, so I don't think that any of the parts are being made currently in the US. I haven't tried this valve yet. As you can get NOS Phillips 7581s (great valve for clean head room), and 6L6WGBs for less I suspect I won't be in the near future.
"As for the JJ 6L6, I just found it to overdrive in a fairly odd manner (lots of bass and treble and virtually no mids at all) despite being a very sturdy valve. This was in a Fender Tonemaster head and once I put some Philips 6L6WGBs in there, it was a whole different amp.
The =C= 6L6 is much nicer and ballsier imo, plus I just like =C= valves better in general.
For preamp valves, like I said before - you'll not likely hear much difference replacing preamp valves in certain parts of the amp depending on the function of that valve. e.g. the PI valve doesn't have nearly as much influence on the tone as the very first preamp stage valve - thats why I suggested getting NOS valves for the initial gain stage."
I tend to play clean so can't really comment on the effects of really overdriving the valves. For clean, JJ-6L6s work well, although I probably prefer =C=.
