Found them ! Matched quad of Mullards EL34 XF2 is coming this way. It’s a little risky because they are not new and the exact number of hours on them is unknown, though supposed to be low enough. Test as strong NOS, as the seller with excellent feedback says. It’s always a gamble with tubes to a degree, I feel fine about it.
Nice! Enjoy - great tubes. Don’t worry about the exact hours on ’em. A meaningless metric, now. "They don’t make ’em like they used too" applies, etc and yada yada...
For Amperex / Hollands I’ve only used the xf4 and xf5 models, both with the brown/red-base. They both sound equally great - I’ve even mixed them in quads (matched pairs), with no problem. The older metal base Philips / Holland version is supposed to be extra special - I’ve almost pulled the trigger on these in the past, but never did.
Perhaps, I should also try Sylvania 12AU7 black plates from 50s as well. What difference would they make compared to RCA black plates from 50s, I wonder ?
Why not? I expect 1950s black plate Sylvanias should be very good. I generally prefer these over any RCAs, though I haven’t tried the 12AU7’s. You can do 5814, 6189 and 5963 subs too. The 5963 tend to be microphonic, so those should be relegated to amp driver slots only (NOT the preamp or phono slots).
RCA black-plate 5963 was the favorite 12AU7 sub for early 2000s-era VAC power amps.
