D-Lab Multi-Plexer

A so called Multi-Plexer is currently up for grabs on eBay. Apparently the circuit was designed in the 70s and only a few units were sold recently. This sound sample is very Sci-Fi almost like a very deep tremolo effect with some slap back reverb. Apparently any sound source can be processed with this box. The auction description mentions an analog signal sent around in a circle and the result being a product of heavy manipulations. It seems like this can almost be a ring modulator with an LFO, but if anyone has info please do comment.