Pultec MH-4 4to1 Tube Mixer schematic wanted.

[TapeOpAl]

Finally registered after lurking for a year or two. Does anyone have a schematic for the Pultec MH4 Tube Mixer? I have one and love it but I'm wondering how it actually works! The inside of the unit is pretty sparse, a lot of the cabling disappears into a mysterious metal box on the back so just curious as to what might be in there...

 

[thomasdf]

I am looking for a schematic too