Spector Tonepump / Michalík BP-4 Bass Preamp

[Sensei Tim]

does anyone have any leads on schematics for these bass preamps?

all of my searches have resulted in "black boxes" that just show the wiring diagram for the pots.

[Sensei Tim]

so i found this:



even tho it's a ken smith preamp, it's supposed to be based on the same circuit.

what;s confusing me are:

the whole gain preset/U2A wiring set up.

gain preset seems like it controls the level of the mid boost/cut in the final signal?
U2A is a gain recovery stage?

not sure about the comments regarding the inverting stage not being correct?