The EMS Synthi A was a portable analog synthesizer (electronic musical instrument) made by Electronic Music Studios (London) Ltd (EMS) in 1971. It uses exactly the same electronics as the VCS 3, rehoused in a Spartanite briefcase. Instead of routing signals using patch cables, as a Moog did, it uses a patch matrix with resistive pins. The 2700 ohm resistor soldered inside the pin vary in tolerance 5% variance and later 1%, the pins have different colours, the 'red' pins have 1% tolerence and the 'white' have 5%, 'green' pins are attenuating pins having a resistance of 68,000 ohms.

The later Synthi AKS incorporated an early digital 256 event KS (Keyboard Sequencer) sequencer in the lid, input provided by a capacitance sensitive Buchla like keyboard .

Perhaps its most prominent use is in Pink Floyd's "On the Run" from their 1973 album The Dark Side of the Moon. Along with Klaus Schulze and Tangerine Dream other frequent users of the instrument include Richard Pinhas of Heldon, Merzbow and Alva Noto.