Thanks, Chris, for asking Roger.
Thanks John V! I did not see the Toroid II schematic that you posted. That explains it well. I think my M2 hotrod/consummate back plate has that configuration circa 2013. If I traced it correctly, looks like the effective inductance values based on midrange selector switch positions are:
-6 dB (5mH + 15 mH = 20mH)
-3 dB (10 mH)
0 dB (5mH)
+3dB (1.5mH)
Those seem to match the ideal values Roger mentioned based on his calculations.
Curious what current and voltage ratings those are, in case you know.
That also explains the new air core inductor with 4mH is similar to what we had before with 5mH (0dB) setting. I never felt the need to set other than 0dB for midrange, and also for Bass control. They interact with one another. 0 dB setting for both has worked for me with my setup.
