Have found out anything about this unit? I guess the unit is a piece of very early quadraphonic equipment. The SFCS position "matrix" must be for the early matrix recordings. Probably QS(RM) would be my guess. The other position "hall" is obvisously for simulating surround/four-channel sound from normal two-channel stereo sources. I believe the "effect control" regulates the amount of Left minus Right which is feed to the rear speakers. Primitive surround simulation uses this trick.
Have you found out what the "MCSS" connector on the rear are for?
Seems to me it has input selection on the front panel for two 4-channel inputs and one 2-channel input. Labelled 4CH-1, 4CH-2 and SFCS and controlled by the "function" rotary selector. Seems also the rear panel has inputs accordingly.
And lots of outputs: 2- and 4-channel rec out, 4-channel output (probably controlled by the volume knob), 2-ch aux output. And a slide switch at the rear upper left corner. And that MCSS connector.... Google was of no help this time.
You are probably right, surteess, the unit is intended to convert a stereo amplifier to a quadraphonic set-up by routing the line out from the existing stereo via the SFCU-2B to a second stereo (power) amplifier. Seems to me the 4-channel out might be connected to both the power amp section of the existing system and the new amplifier, making system volume control possible via the SFCU-2B's "master volume".
I would like to see more documentation on this unit. (And as this is the "2B" I would guess a model "1" would exist, and I think I once saw a picture of that published by JVC_Graz (Klaus).
Ah yes jvc_graz that is where I have seen it also, the first picture from above thread is from a year magazine that JVC used to put out to show the range of equipment (I actually have that one + about 6 others from quad era).