Origins
ARP Instruments introduced the Pro Soloist in 1972 as an evolution of their earlier Soloist model. While ARP had established credibility with professional studios through the modular 2500 and semi-modular 2600, the company recognized a growing market for portable, performance-oriented instruments that required no programming expertise. The Pro Soloist targeted working musicians who needed reliable, expressive sounds without the complexity of patch cables or synthesis programming.
Design & Technology
The Pro Soloist featured 30 preset monophonic voices selected through toggle switches positioned above the keyboard. Unlike the earlier Soloist, the Pro Soloist employed digital ROM chips to store voice configurations, significantly improving tuning stability—a major weakness of analog preset synthesizers. This digitized tone generator represented an innovative hybrid approach, combining digital control with analog sound generation.
The pressure-sensitive keyboard supported aftertouch, allowing performers to control growl, wow, brilliance, portamento, pitch bend, and vibrato through key pressure. Four slider controls adjusted volume, touch sensitivity, brilliance (filter cutoff), and portamento speed. A three-position octave switch extended the three-octave keyboard's playable range to five octaves.
The single oscillator generated pulse and sawtooth waveforms simultaneously, with the sawtooth created by summing five pulse waves into a 64-step staircase approximation. Three resonator banks provided filtering options emulating cello, violin, flute, and oboe characteristics.
Production History
ARP manufactured the Pro Soloist from 1972 until the company's bankruptcy in 1981. The instrument underwent revision as the Pro-DGX, which replaced toggle switches with momentary digitally-latched push buttons with LED indicators. Despite competition from Moog, Korg, Roland, and Farfisa, the Pro Soloist maintained steady sales throughout its production run.
Notable Users
The Pro Soloist appeared on numerous influential recordings. Tony Banks of Genesis used it prominently on Selling England by the Pound (1973) through Seconds Out (1977). Gary Numan built his 1980 number one album Telekon largely around the Pro Soloist. Josef Zawinul, Vangelis, Tangerine Dream, and John Entwistle all incorporated its distinctive tones into their work.
Steely Dan's Donald Fagen famously destroyed his temperamental Soloist during the recording of Countdown to Ecstasy (1973), an incident that highlighted both the frustrations and the unique character of early preset synthesizers.
Cultural Impact
The Pro Soloist demonstrated that preset synthesizers could find professional acceptance despite initial skepticism from serious musicians. Its digital control of analog voices pointed toward future hybrid instruments. While overshadowed by more programmable instruments, the Pro Soloist helped establish the category of portable performance synthesizers that would eventually evolve into modern workstation keyboards.
Market & Collectibility
Pro Soloist synthesizers command moderate prices on the vintage market, reflecting their relative availability compared to rarer ARP instruments. The Pro-DGX variant is particularly sought after for its updated interface. Functional units with intact aftertouch functionality are preferred by collectors and musicians seeking authentic 1970s textures.