1974 - 1977.
JC mean John Curl, the designer.
Models starting with serial number 2148 differ from previous units.
Rolv-Karsten Ronningstad says :
I am pretty sure that the connection between the emitters of the 2N4401 and the 2N4403 transistors in the second stage of the "phono" module should be removed. I am not sure, though. I think it will work anyway. I have never simulated this module with my PSPICE. The line module I have simulated, and that one simulated well, I remember. John Curl's correction to the Line module was that as it is in the drawing you got the signal from the E212 to the 2N4403 should have been taken from the OTHER E212. The same applies for the E175 and the 2N4401. I'll send you the drawing when I find it. I also think that dual JFETs instead of the J110, J175 and J212 should be possible to use. Then you can avoid the matching. I think there is a dual n-channel JFET named 2N5565 or similar that can be used for the J212, and maybe the analogue switch AH5012 or AH5020 can be used for the J175 (p-channel). These components are analogue switches, but they are really p-channel JFETs. I don't know exactly for the J110 (Ahhh, I am using E110 and J110, but they are identical inside. I used the "J" versions), though. Maybe some Japanese transistors could be used. Check at Ernš Borbely's page, http://home.earthlink.net/~borbelyaudio he has lots, and he can also match transistors for you.
