In the rare case you happen upon matched pairs of these transistors, and you like drilling, and you think my boards may be Ok, then go ahead and read this blog.
As a starting point, we settled on this schematic for the working amplifier. Some modifications were done from the original, and Botte made some changes to get a slower turn on rate for the boards.
Note, R37,R38 and C1 and C2 have been changed. However, feel free to use original values.
Also note, for greater viability of use of JFETs beyond 8ma IDSS, source resistors can be used here ( I used 10R with 9ma pairs) - Otherwise jumper this location.
Q13 and Q14 are BC550c and BC560c. Originally Toshiba bipolars were used on my boards, but they were not stable in voltage and gain suffered on the boards. The boards have since had the pads altered to remove...