A quad VCA integrated circuit originally designed by SSM. It is one of the few SSM designs that remained in production when Analog Devices acquired the rights to the SSM library, and it remained in production there until 2012; as such, it was one of the few designs rendered by either SSM or Curtis Electromusic that was ever produced in a surface-mount version. It was noted for ease of use, being able to be integrated into circuit designs with a minimum of external components or support circuitry.
The 2164 entered the market a bit too late for the 1980s polyphonic synth era, and as such saw little use in commercially produced synths, although Doepfer did use it in several of their designs. It found its main market in studio audio processing circuitry, and communications devices. It was used extensively in a variety of synth DIY designs and by manufacturers such as Intellijel. As of August 2014, the 2164 is in production and available from Coolaudio.