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Kenton Pro Solo

MIDI-CV Converter By Steve Howell
Published September 1995

Kenton Pro Solo

Kenton Electronics' new one‑channel MIDI‑CV converter is slightly more expensive than others of its kind — but there's a reason!

Kenton were probably the first company to make a living out of retrofitting MIDI interfaces to pre‑MIDI analogue synths, and very successful they have been too, offering retrofits to most of the popular models. More recently, they have moved into the world of MIDI‑CV conversion, developing the Pro 2 (reviewed in August 1992's SOS by former Editor Paul Ireson), a stand‑alone 2‑channel MIDI‑CV interface that can be hooked up to any synth sporting CV and gate inputs. More recently, we have seen the Pro 4 (reviewed by Derek Johnson in SOS, September 1994), a 4‑channel, fully programmable converter so comprehensive that it includes all but the kitchen sync! [Groan — Ed]

However, what if you desire the far‑reaching programmability of the Pro 4, but have only a single monosynth to drive from your MIDI setup? With this in mind, Kenton have just released the Pro Solo MIDI‑CV interface.

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. In other words, most converters I have used simply turn a note on at a particular pitch and then turn it off again. Whizzy solos, funky vibrato, sensitive dynamic control? Not a chance!

Going Solo!

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 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 your synth's 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 a variable rate, and an assignable controller to switch it on or off, in addition to the option of single or multiple triggering. And 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.

Basically, if you have an old analogue monosynth, place your order now! You won't regret it.

In Use

With just three buttons, operation is a tad fiddly — but at least the Pro Solo works on the basis that once you've set it up, you can forget about it! A menu on the front panel shows the 20 functions on offer, and a single button allows you to step through them. These functions include the ability to set the unit's MIDI channel, portamento time, LFO speed, waveform and MIDI sync, pitch bend range, VCO scaling, triggering options, note priority, gate type, transpose amount, and fine tuning. You also have a comprehensive range of functions that let you select which MIDI controller will activate LFO modulation or portamento, or control the auxiliary output.

A pair of Up/Down buttons set the value for each parameter, and a simple 2‑digit LED shows the value of the current menu item's parameter numerically. Given the restricted nature of this display, messages are sometimes a bit inscrutable, but well within the understanding of anyone even vaguely familiar with such practices. For all parameters, sensible defaults have been chosen, so not much work is needed to get the unit up and running.


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 November 1994, 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?


If you're unfamiliar with the subject of MIDI‑CV conversion, and are a bit baffled by some of the terminology in this review (Hz/Volt, S‑Trig, and so on), take a look at Tom Carpenter's thorough article on the subject in SOS March 1995.


  • Transmits pitch bend and glide faithfully.
  • Built‑in LFO.
  • Handy Auxiliary CV output for dynamics or filter control.
  • Good range of parameters assignable to MIDI controllers.


  • Slightly fiddly to set up.
  • 2‑digit display sometimes a bit inpenetrable.


More like a quarter of the amazing Pro 4 than half a Pro 2 (and priced accordingly), this is the most well‑specified one‑channel MIDI‑CV converter I've come across. The Pro Solo will not only give you MIDI control of all an old monosynth's features, it can actually open up some new possibilities as well.