Cherry Audio Pro Soloist

Cherry Audio have resurrected the venerable ARP Pro Soloist in software.

I make no bones about my love for the ARP Pro Soloist, and I wouldn’t be surprised if there were secret cabals in SOS‑land who regularly take the piss out of me for referring to it in reviews of other equipment. I don’t care. Every time that Korg have hinted at another recreation of a vintage ARP, or Arturia have teased their next slew of soft synths, my fingers and toes have been crossed in the hope of an accurate recreation of this funny little preset monosynth. And, finally, it’s arrived. But it’s come from elsewhere...

You might be wondering what made the Pro Soloist special, and why I think that it remains so. To answer this, let’s return to 1971, a year in which changing from one synthesized sound to another was an activity that could at best be described as hit‑or‑miss. Most of the time it involved repatching, although, on the new‑fangled Minimoog that was just about to appear, a pre‑defined signal path meant that you needed only press a few switches and twist a bunch of knobs to obtain something that — if you were lucky — approximated the sound you wanted. But this was also the year in which ARP released the Soloist, a small synth that allowed you to jump from any of its 18 preset voices to any other at the flick of a toggle. Not only did this sound great, it introduced something revolutionary that we now take for granted. Despite Cherry Audio’s website and manual claiming otherwise, the Soloist boasted aftertouch with up to six simultaneous destinations: pitch, vibrato, wow, growl, brilliance and volume.

You might be wondering what made the Pro Soloist special? To answer this, let’s return to 1971... the year in which ARP released the Soloist, a small synth that allowed you to jump from any of its 18 preset voices to any other at the flick of a toggle.

The Soloist was a marvel but, sadly, it was flimsy and prone to failure. So, the following year, ARP release the Pro Soloist. This also had its shortcomings, but it exuded one quality that overrode any criticisms: its 30 presets could sound amazing. But how? Surely, it’s just a single‑oscillator preset monosynth with a signal path comprising nothing more than a VCO, VCF and VCA, right?

No. Wrong. Very wrong. In many ways the Pro Soloist was the most innovative of all ARP’s synthesizers, and much of its architecture was unique, including a digital keyboard scanning system and a fascinating audio generator that comprised a high‑frequency oscillator driving a logic counter, which in turn produced a stream of pulses that were used to generate the initial waveforms. Then there was the way that ROM chips were used as switch matrices to change the voicing when you selected a new preset. Furthermore, there were multiple signal paths through the synth, one of which passed the oscillator’s output to three filter banks containing 10 tuned resonators. When you selected a voice, a bunch of digital gates directed the signal through (up to) five of these resonators to obtain complex timbres that, even today, can be produced on little short of a modular synth or its software equivalent. Not only could the Pro Soloist produce orchestral sounds that were more accurate than anything else of its era, its aftertouch made it one of the most expressive synths ever produced, and some of its sounds remain revered to this day, especially amongst fans of mid‑’70s Genesis [check out Tony Banks' 'Riding The Scree' synth solo, from The Lamb Lies Down On Broadway album, for a great example of the Pro Soloist's capabilities - Ed]. The Pro Soloist was itself superseded by the Pro/DGX in 1977, but later versions of this replaced the revered ARP4012 filter of the Soloist and ARP4034 of the Pro Soloist and early Pro/DGXs with the ARP4075, and were considered (perhaps rightly) as inferior, so we’ll say no more about it.

Standing On The Shoulders Of Giants

The Performance screen of Cherry Audio’s Pro Soloist looks much like the original synth, although a closer inspection reveals that it’s a hybrid of the Pro Soloist and the Pro/DGX and offers several new features, including aftertouch‑controlled wah‑wah and tremolo. Since the GUI is too small to contain everything that the soft synth offers, a second screen provides access to all of the hidden goodies of the Pro Soloist and then adds many more. For example, you can now program the sync’able LFO and both contour generators, access all of the wave generation in the oscillator (which now...