The Pro-Solo arrived in an era when connecting MIDI keyboards to vintage synthesizers meant wrestling with incompatible control voltages and missing performance features, and Kenton Electronics built this converter to bridge that gap with surprising sophistication packed into a brushed aluminum box smaller than a paperback book.
At its core, the Pro-Solo is a single-channel MIDI to CV converter powered by a 32-bit ARM processor, translating MIDI data into control voltages that speak the language of classic monosynths. It outputs pitch CV through high-specification 16-bit D/A converters for rock-steady tuning, a programmable gate output that handles both V-trig and S-trig standards, and a flexible auxiliary CV output for controlling filters, VCAs, or other modulation targets. The unit measures 130 by 97 by 40 millimeters and weighs 450 grams, making it genuinely portable. You get three buttons and a two-digit LED display for editing, which feels minimal but works because most parameters stay put once configured. The converter supports V/oct, Hz/V, and 1.2V/oct scaling, handles pitch bend ranges up to 48 notes in either direction, and includes portamento with both fixed-rate and fixed-time modes. There's also a built-in LFO with nine waveforms including random, which can modulate pitch or the auxiliary output independently, and it syncs to MIDI clock if you need it locked to a sequencer.
The Pro-Solo earned respect among hardware enthusiasts for its faithful transmission of performance data and its ability to restore expressive control to synths that originally lacked it. The auxiliary output proved particularly valuable for velocity-controlled filter sweeps or aftertouch-driven modulation, features that many vintage instruments never had. Some users found the three-button interface tedious for deep editing, but the sensible defaults and non-volatile memory meant you could set it up once and leave it alone. The unit remained in production long enough to spawn multiple revisions, with later versions adding extra auxiliary channels and expanded clock division options, testament to a design that solved a real problem in a way that still holds up.
