I've built a Darling that is very similar to the Clementine. That might sound a little bit academic, but I've never liked the poor low frequency response at 20-100 Hz. I've always held the OTs responsible for that. Today I checked the voltages at 20-200 Hz before the coupling cap, after the coupling cap and at the anode of the 1626. I was very surprised to see that the the poor FR is already present at the primary. It does not matter whether I connect a 5k or a 12k OT. Here are the voltage curves (y-axis, relative units).
Schematic:
Anybody any ideas?
Mike