So you've built up an enviable collection of analogue synths, but how do you incorporate them into your MIDI setup? Brian Hamlyn dusts off his Wasps to test the well-endowed Pro 4 from Kenton Electronics

In the light of a never-ending stream of variations on the sample playback machine, with their "controls" buried in software and poor visual feedback of parameter settings, it should be no surprise to see a swing back to analogue synthesis with its intuitive interface (knobs).

Of course, they sound great too - their capacity to create complex cross-modulations can produce sounds which evolve over long periods of time, and the sheer grunge of analogue filters digging into raw waveforms is never quite captured by synths from the digital age.

To incorporate these synths into a MIDI system, it is necessary to convert MIDI data into Control Voltages and gate pulses, and Kenton's Pro-2 is probably the most widely used 2 channel converter on the market.

Now their long-awaited Pro-4 provides 4 channels of MIDI/CV conversion with software LFOs, portamento and a number of additional features including DCB & Wasp outputs. It's very much more than a pair of Pro-2s in a rack mount.

Hands-on

If you're familiar with the Pro-2, scrolling through the backlit 2 x 20 character LCD display won't be a problem. Even if you aren't, the manual guides you smoothly through the interplay between Parameter/Value buttons and Data Entry rotary whereby you access the 128 variable parameters.

The unit is structured as 8 independent sections labelled channels A-H, each of which can be assigned to receive on any MIDI channel. Global settings for all 8 channels are referred to as "Setups", 8 of which can be saved, plus the usual Sysex bulk dump/load facilities if that's not enough (or you're one of the few who remembers to back up).

Channels A-D are the 4 main converters, providing 1 volt per octave CV (4 channel Hz/Volts board available for early Korg/Yamaha synths), gate and trigger outputs (7 types including S-Trig for Moogs) per channel. Software features for Channels A-D include:

Note Priority - lowest/highest/newest

Transpose - Up/Down 2 octaves in semitone steps.

Pitchbend - Range selectable in semitones up to 2 octaves, added to the CV out.

Portamento - Switchable over MIDI with the option to set either the usual Rate parameter or Time (in which the time taken to glide between semitones remains constant irrespective of how far away the destination note is).

LFO Depth parameters allow modulation to be added to the Channel CV output from any of the 4 available software LFOs, the amount of which can be determined by pitchbend, velocity, aftertouch or any of 121 continuous MIDI controllers with the highest/lowest ranges user-definable.

Next are the 8 Auxiliary CV outputs, which can be derived from any of the MIDI channels being used by Channels A-H, and convert bend, velocity, aftertouch or any controller into a CV output with range and reset value parameters.

Additionally, the first 4 can also route the LFOs to the outside world with the same modulation parameters available as Channels A-D. All CV/Gate/Trig outputs are on 3.5mm jacks.

Channel E provides an output for EDP Wasp/Gnat etc, with note priority which shares a 15 pin D-type socket with the DCB port. All necessary leads are available from Kenton.

Channel F is a MIDI Filter/Channeliser output, useful for early MIDI spec instruments which often default to Omni on or channel 1.

Channel G is a DCB port for connection to Roland Juno 6/60, Jupiter 8 etc.

Channel H is the Kenton Analogue Digital Interface (KADI) output, which has another 15 pin D-Type output to play the voices on suitably modified Roland drum machines such as the TR808/606 from MIDI note ons. Kenton hint that there may be additional uses for this output in the future.

As with the Pro-2, there is a Sync 24 output (Bassline, TR drums etc) and an arpeggiator output socket, which outputs pulses (normal or inverted) at a rate which is a division of the incoming MIDI Clock signal.

Trigger happy

Now, about those LFOs. In Free Running mode, they have a range from approx 0.1 Hz (10 seconds per cycle) up to 22 Hz (22 cycles per second) and offer a choice of 9 waveforms including Tri, Saw Up/Down, Square, Sample & Hold (random).

Add to this the potential to sync the LFOs to MIDI, and things get interesting. MIDI Clock is divisible by up to 24 to control Rate, and if you check the waveform on a scope, there is no evidence of any "lumpiness" caused by retriggering.

That's a lot of control, but it's only when you consider the ways in which you might use these outputs that the real potential of this machine comes to light.

Consider playing a block chordal part which is also sent to the wonderful Juno/Jupiter arpeggiators via DCB, the lowest note playing a monophonic part with synced S/H filter modulation, the highest a lead line with portamento (shame there isn't a legato mode) and aftertouch vibrato. Before you know it you've reinvented the ARP Quadra, and you can just prog yourself off to the 70s.

Hook it up to a computer and there are masses of possibilities for sequencer controlled (and editable) synth and effects modulations, which can be repeated and saved to disk. If you've ever tried to get several synths with LFO swept filters to produce reasonably predictable results throughout a session, you'll appreciate the significance of this.

Hook up the TR909 and the Bassline, no need to MIDI retrofit an old Jupiter 8 or buy MIDI filter hardware for JX3Ps, get the Wasp out from under the bed, play a TR 808 from an Octapad, guitar and wind synth players especially have access to enormously expressive control of analogue synths via the Pro-4.

Take it further and the Pro-4 can help towards mix automation, sending volume changes to analogue synths' VCAs, synced autopan via extra VCAs, or controlling old effects with CV ins (eg: Roland SBF 325 Flanger/MXR Pitch Transposer etc)

Actually, many of the pedal inputs on modern equipment can receive and make use of CVs generated by a unit like this, but (obviously) don't just plug things in randomly 'without seeking professional advice', unless you're prepared to face the consequences.

Bass-o-matic

Just think of all the cross mod routings available to the Happy Patcher with the addition of a few simple voltage processing units (and a patchbay) sending the Kenton's CVs and their inverted forms to synths which can easily be fitted with extra inputs to "open up" their component modules.

The integration of MIDI gear, analogues, and effects rack into a sensible working system comes closer to being a possibility.

My beef about the Pro 2 was its usable CV range, which was the equivalent of a 61 note keyboard. The Pro-4 rectifies this with an 88 note span, supplying an extra 2 octave shift in either direction if required. That takes the lowest CV down to -5 volts which is actually below the useful range of many synths, but then we've all grown obsessive about how low we can go in recent years haven't we?

Originally scheduled for release 2 years ago, the delay in the Pro-4 hitting the streets has been caused by designer Jonathon Price's insistence upon cramming every last byte of available ROM space with extra facilities.

The Wasp & DCB ports were planned as optional retrofits at £35+ VAT each, but Mr. Price decided to include them at no extra cost, to avoid wasting time on taking units back to retrofit the boards. Such commitment to quality in an industry which more typically treats its end users as beta testers should not go unmentioned.

Even as the first units are about to hit the shops, future ROM updates are being planned, hopefully to include a Polyphonic Mode (Oberheim 4 voice owners take note), an interface for the non-standard Jen SX1000, and micro tuning capability.

Verdict

The equipment this unit controls may be considered obsolete by the manufacturers, but the second-hand market is thriving, allowing traders to define 20 year old technology as "vintage", with prices to match.

How ironic that in the age of built in obsolescence, I find myself reviewing a device designed to turn the tables and effectively recycle the instruments which "they don't make like that any more".

If the Pro-4 is a runaway success like the Pro-2 before it, perhaps it will finally dawn on the manufacturers what we, the end users have been wanting for years.

The essentials...

Price inc VAT: £399

More from: Kenton Electronics, (Contact Details)