jimfet wrote on 05/21/08 at 18:07:54:Well I got my Zbox a couple of months ago. I love what it has done for my CD player. I just don't know why it shipped with a JJ 12ax7. To me that is one bad sounding tube. It may be because it is new and hasn't broke in yet. But I also have a new EH 12au7 that blows it away. The JJ is just to much distortion.
But after much rolling the 2 tubes I mainly use are the NOS RCA 12au7 black plates and the clear tops. The black plates are best for new recordings. Very precise and clean, great bass.
The clear tops are my best for old recordings. Those days when it's going to be Frank, Ella and the likes, it's the clear tops for sure. The thing about the cleartops for new recordings they are a little laid back. Stings and vocals are back with the band, instead of slightly forward where I think they should be. But with old recordings where horns, vocals and strings seem to be too forward, the cleartops tame them down where they should be. Which also gives the illusion of more bass which is need on older recordings. Just my 2˘
Jim, I think the 12AX7 just has too much gain for the ZBox, and really I would bet Steve meant to send you a 12AU7 or 12AT7.
I have found that 12AU7s work best for me in both the ZBox and the DEC685. So if you prefer the 12AU7 I don't doubt that it is what you should be using.