RSF

RSF was a small French synthesizer company active in the late 1970s, best known for creating the Kobol, a monophonic analog synthesizer released in 1978 that earned the nickname 'the French Minimoog' for its compact design and versatile sound-shaping capabilities, including two oscillators with morphing waveforms. The company followed with the rack-mountable Kobol Expander in 1979, which stripped the keyboard version to its core VCO, VCF, VCA, and LFO sections, and later the Expander 2 adding features like ring modulation and sample-and-hold. Prior to these, RSF produced larger instruments such as the Modular Model 11 series; limited production—fewer than 200 Kobol keyboards and around 800 Expander units—made their instruments rare collectibles today.