The Steiner-Parker Synthacon was a monophonic analog synthesizer built from 1975-1979 by Salt Lake City-based based synthesizer manufacturer Steiner Parker. It featured three voltage-controlled oscillators (one of which could output sine and sawtooth waves and two of which could output sawtooth, pulse and triangle waves), a two-pole resonant Sallen Key Filter, two ADSR envelope generators, a pink- and- white noise generator, and a 49-key keyboard. While the Synthacon was not a modular system, signal routing could be achieved through a series of switches. Interestingly, the Synthacon's filter can self-oscillate like the Minimoog, but has an opposite polarity so it doesn't lose any volume when resonance is increased as do the Minimoog and Arp Odyssey's filters. Earlier models of the Synthacon had silver-faced front panels. Later a duophonic upgrade, the "Two Voice Synthacon" was released.