the tung-sol 12ax7's are a very nice preamp tube, I use them all the time in my ROV v1,v3, balanced v5,,no complaints there.
I read your post a couple hours ago and figured I would go down and
put my SED el34's in to try and compare them to the jj6l6's ive been using for the last month or so. I own the sed el34's,,jj6l6's and
the mesa 6l6's. I swap them around periodically for a different sound when I need something new again. I cant really compare the SED's to any other el34's because I dont own any but I can help a bit comparing them to the jj6l6's ive been using recently.
The first thing I noticed is the SED'S had less bottom end than the jj6l6's, I left all my settings on the amp the same after the swap. The SED'S had a more pronounced mid range to them. I thought the jj6l6's have a better sounding clean though not much better, I was able to improve the SED'S by raising the treble some. After a while of playing I swear the SED;s give my amp a sort of 3d sound to them,,I cant think of a proper way of explaining this,,maybe fuller,rounder,deeper not bass wise. Its hard for me to come up with something better than that but the SEDS's offered something I havent heard from my amp in a while using the jj6l6's. I noticed a poster above said they sounded boomy,,I wont say he is wrong but I didnt find that at all with mine,,matter of fact I thought I might need to add some bass. I thought the SED'S seemed to smooth out my lead sounds some probably due to the mid range they offer,,a bit more like a marshall sound but not dead on. I also noticed pinch harmonics seemed to work really easy tonight but who knows if that has anything to do with a power tube or not,, maybe the atmospheric pressure, is it a full moon??? Anyways I think they are a good choice for some el34's,,I enjoy them. Good luck
