>>Phil do you have a favorite 845 Tube for the Carissa? It is coming with the KR 845<<
The KR 845 is built and sounds different than a vintage RCA or Amperex 845, or the Shuguang tubes patterned after them. Earlier in the KR's production there were some serious reliability problems deriving from the KR's ribbon filament. Like all KR tubes, that example is otherwise beautifully constructed. The ribbon filament problems were a design and execution issue. I don't know whether the high incidence of problems with that tube have been resolved more recently. However, that tube has a robust, transparent sound that in some systems can be icy but always very clean toned.
Once you get into tube rolling, preferences get very personal and it surprises me to hear the wide range of variances in how two people who have generally the same sense of audio fidelity can land on the question of which 845 power tube to use. For the tonally sophisticated 845 amps, in which I'd include the Carissa, I generally prefer the Shuguang 845B graphite plate tube among current available production. It has authoritative shove, deep bass with very good definition, beautiful midrange and the top end has very fine transient body but never sounds strident. The metal plate 845C has an initially exciting spray of focused detail. In a high end 845 with wideband output transformers and a fast circuit, that tube will sound strident. But on a vintage-voiced 845 SET like the Japanese Triode 845 or some of the inexpensive Chinese 845s, it can wake up the amp and give it speed and detail that its warm voicing otherwise obscures.
Similarly, you wouldn't want the 845C in a system with Essence and it's cold ribbon super tweeter, but it can be just the thing with, say, a pre-v4-08 Druid. So KR 845 may be too strident on Essence depending on the rest of your gear and how reinforcing of treble your room is. It's a borderline call. On Superfly more of a matter of taste. I think with both speakers the affordable and widely available 845B is the best choice. Also true with Definition. I haven't yet taken the time to find out whether the Shuguang Psvane 845 is worth its price relative to the 845B. I'll also add that the graphite plate 845B has proven both reliable and long lasting in my Audion Black Shadow monoblocks.
Phil
