Help Identify Streamer Stage 2 (91) Electronics Setup

Hi Folks!

I've been using my SSII with great pleasure over the past few years with a straight sound. It's only recently, through new musical opportunities, that I've started fiddling around with the settings to look for new sounds (essentially some more presence in the low end ).

Fact is I have realized that I have no idea how the electronics work on it and when crawling the web for schematics didn't manage to find one that explained how my bass is actually set (seems to be either an old setup for SSII or a custom/home-made one)

Quite obviously there seem to be a main volume knob which also acts as a passive/active push pull as well as a balance knob. The 2 remaining knobs are "doubled" knobs. I suspect each of them controls one of the pickups but I'm a little unsure how they actually function. Could anybody here help me understand what they are and how to make good use of them? (pictures attached)

Thanks and apologies if that's an obvious one !

 

Aftermarket mod - looks like emg bqc 4 knob setting

The stacked knobs should be

bass, treble and mid,mid frequency

 

Oh that's it yes! By better looking at the elements inside I did fnd the EMG reference for the 2 stacked knobs. The other 2 (volume and balance are MECs, probably the original ones). Thanks a lot Schlobodan and Hoggles for pointing me in the right direction! Now I know where to look to understand how these work