This video, via Dmitri SFC, captures a modular performance by Doug Lynner on the ‘Mystery Serge’ at the Serge Modular 40th Reunion. 

According to a discussion at Serge.Synth.net, Lynner purchased this Serge modular synthesizer in 1975, while he was a composition student at The California Institute Of The Arts in Valencia, California.

It is believed to be the first “commercial” Serge, i.e., it was built on order for Doug, not by him. It started life as a 4-panel system plus a spring reverb boat. It was used to do a lot of demoing for Serge, so the reverb was quickly replaced with a 5th panel of modules.