Review - PRO-SOLO, Sound on Sound magazine
I have used many MIDI-CV converters in my time (although never a Kenton!), and have found every one to be lacking in some way. Few convert the movement of your MIDI keyboard's mod wheel into anything a pre-MIDI analogue monosynth can recognise and use - so bye-bye vibrato, or indeed modulation of any kind. Note triggering, also, has often been a problem, with many converters offering neither proper single or multiple triggering, and requiring a very precise playing technique for clean articulation of notes. Because most pre-MIDI synths' external CV/Gate inputs override the portamento (glide) function, you can't use glide on your MIDI keyboard and expect that to be converted and reproduced on your monosynth either! Finally, some converters offer little in the way of velocity control over tone and/or amplitude.
So what has all this to do with the Kenton Pro Solo? As it turns out, the answer is absolutely nothing, because the Pro Solo overcomes all of these shortcomings, and offers much more into the bargain. The Pro Solo's pitch bend is mixed into the main cv output - so no problems reproducing pitch bend faithfully over MIDI. The Pro Solo also has its own internal LFO (with a choice of nine waveforms), and this too is mixed into the main CV output and governed from the mod wheel (or assignable to any other controller you want) for immediate control of vibrato. This alone justifies the purchase of the Pro Solo in my mind, as it allows the same performance control you would expect from the original synth (or, in the case of my Oberheim SEM, better control).
The fact that the Pro Solo has its own LFO for vibrato also means that your old synth's own internal LFO can be put to good use for filter, pulse width and sync sweeps - or even as another audio generator (if you have a MiniMoog, for example, you can free the third oscillator from its modulation duties to add some extra welly to your sounds). The Pro Solo's on-board LFO can also be triggered by MIDI clock, so that sweeps can be in sync with your sequencer. Furthermore, the LFO can be piped out through the Pro Solo's auxiliary CV output, so that it can control other devices you may own -assuming these others have suitable CV inputs to receive the output. This can help if your own synth's LFO is a bit challenged in the waveform department - after all, some older synths only offer triangle and square your waves. While we're on the subject of the Pro Solo's auxiliary cv output, this can also be used to route any MIDI
controller to synths filter or VCA CV inputs (if it has these), allowing you, for example, velocity or aftertouch control of dynamics.
The Pro Solo also offers glide with lastly, if your vintage monosynth happens to be a Moog with an S-trigger input for note-on, or a Korg or Yamaha using the less common Hz/Volt oscillator tracking, no problem - all of these can be driven via the Pro Solo. All in all, most of my previous MIDI-CV converter gripes have been addressed.....
In short, the Pro Solo is the MIDI-CV converter I've been awaiting for 10 or more years. It has breathed new life into my much-underused Oberheim SEM, which is now a key weapon in my noise-making armoury. Although I gave CP Technology' S Missing Link MIDI-CV converter a good review on the Widgets page of SOS last November, this was based on the fact that for under £100, it was the cheapest, cutest converter around at the time. However, I have to say now that I believe the extra £20 - £30 required for the Pro Solo will buy you a much better converter that will not only give you terrific performance control, but also actually expand your old synth's functionality. Basically, if you have an old analogue monosynth, place your order now! You won't regret it. And before anyone puts this down to a nice lunch courtesy of Kenton and a freebie unit to a highly respected reviewer, forget it! I saw their ad, bought one on spec (at full price!) and then reviewed it. Need I say more?
Review by Steve Howell