An integrated circuit containing two VCAs, made by Curtis Electromusic. It provided both linear and exponential control voltage inputs for each VCA. Buffering for the gain cell had to be provided externally; this was a deliberate choice so that the circuit designer could tailor the operating characteristics of the amplifier. Curtis also offered a 3335 variant which lacked the linear control inputs, but was physically smaller and cost less.
Like most Curtis IC's, the 3330 and 3335 are long out of production and should be reserved for repairing vintage synths that require them.