wakoo Schwäb ...... more control current for both CCS-es ( input one and one for biasing of upper Jfet )I have proper parameters with 12K triple and BC556B-s , but seems that sp300b have problem using BC560-s
so - this way - every control bjt is having ~3,3mA through ; that means - plenty of control current , what means more stability
your typo
I presume that you have few 2SK170BL around ?
try them instead of J310-s , as core LTP in Pumpkin
or 2SK369BL ...... if you have them ....