Hi,Schuguang makes the very best 845 (IMHO), named 845-B, copy of the original Amperex 1930. Copper base, double getter, no top mica spacer for less microphonics. I have used the Tienjin 845 for 6 years, and the new 845-B is a great improvment. Cetron 845-B is not so good, and KR is of different design, with a different heater.
A good review from Ed Sawyer (TNT audio) is on jacmusic.com
Schuguang will soon make a metal plate 845, called 845-M. I haven't tried it... ![](http://www.audioroundtable.com/emoticons/smiley.gif)
Ciao