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Groove Electronics

Groove Electronics Midi-2-CV Converter


Studio Test: Published november 1989 in IM&RW


  • Apart from offering MIDI retrofits for antiques like the Roland Juno 60 Jupiter 8, and Roland TR8O8 drummachine (reviewed escatically in IM Jan'89), Groove have now set their sights on voltagecontrol monosynthi, with the launch of the MIDI-2-CV, a dual-channel MIDI-to­control-voltage converter which will make practically any 1-volt-per-octave monosynth respond to your MIDI keyboards. With the sounds of MiniMoogs and other dinosaurs now sought after by the Acieeeed! crowd, if you have any beloved old monosynths, the MIDI-2-CV could be the best investment you'll ever make.
  • There have been MIDI-to-CV converters in the past, but none this comprehensive. At first sight the MIDI-to-CV looks incomprehensible but a short session on the manual soon allayed my doubts - the thing works, and it's very flexible. The steel case is sturdy and the eight soft-touch control buttons unbreakable, so there'd be no problems using it on stage. Around the back there's a MIDI IN and THRU; and, on the basic model, Control Voltage, Gate and Level minijack output sockets for a single synrh. Down the side are small holes giving access to the calibration screws for the outputs; pitch-scaling, tune and bend amount.
  • The first thing you have to do is warm up your synth and adjust these pots until it tunes and spans correctly with your MIDI keyboard. In order to provide a full note-range, the MIDI-2-CV produces a bipolar control voltage from -3V to +4V. Some synths don't like negative voltages, so they won't play below Middle C (OV ); however, the Transpose function should solve this problem The MIDI-2-CV also generates a pitchbend voltage from MIDI pitchbend data; by adjusting the Bend pot, you can control how much effect this has on your synth.
  • While the MIDI-to-control voltage routine sets the monosynth's pitch, the Trigger actually plays the notes. The standard MIDI-2-CV caters for three kinds of Trigger; Positive Going, Ground Trigger, and Negative Going. Optionally, you can have a Moog S-trigger fitted too. The Level output controls the synth's filter cut-off frequency which can be controlled by MIDI velocity, mod-wheel, after-touch or breath control.

  • Editing
  • Editing MIDI-2-CV parameters is achieved through the eight control buttons, A-H; the problem is that all system messages are conveyed by the flashing LED's. Both the sequence of lit LEDs and the speed of flashing (slow or fast) has to be taken into account. For instance, "+O+OX1OO" (Slow, Off, Slow, Off, any value, On, Off, Off) means "Edit Mode, Trigger Type, Positive Selected". Fun, no?
  • So what parameters can be set for each syrith? Key range for any synth can be transposed up or down three octaves; MIDI channel can be set from 1 to 16 -there's no OMNI mode. Key Priority selects whether the highest, lowest or newest note triggers the synth; Level Source determines whether Breath Control is in operation. Aftertouch, Mod Wheel or Velocity controls the signal to the synth's Filter Cutoff. There's a lot more, some of it only of interest to owners of particularly obscure synths, but it's fair to say that everything you can think of is catered for.

  • Options
  • The MIDI-2-CV is available in several different configurations, depending on your needs. The version we looked at had all the bells and whistles, but you can save money by only ordering the required options. You can have a second set of sockets for another synth (£25 ), which can be controlled from a different MIDI channel. A third socket gives you an independent MIDI channel for an EDP Wasp/Gnat synth (£20). This is the first time anyone has bothered doing anything for the wonderful Wasp. Now, rather than having to dig up a Spider sequencer, you can MIDI it with the MIDI-2-CV
  • Other options include Din-Sync, which allows you to synchronise old Roland drum machines (such as die TR808 ) to a MIDI clock (£25 ). If that weren't wonderful enough, there's an Arp Clock option (£20), so you can drive the arppeggiator of your Jupiter 4, or even your CR-78 drum machine. Bliss! There's also a memory (£20) so the MIDI-2-CV will store sixteen setups for instant recall, and, as an alternative to MIDI-CV functions, a software update drum trigger system (£45) for Simmons-type drum modules (up to six, with the second CV fitted. )Although the MIDI-2-CV will not work with the kiloHertz/Volt monosynths produced by Korg and Yamaha, another option converts from one standard to the other; £15 permanently fitted, £35 if you prefer it as a stand-alone box to keep the basic unit flexible.

  • Conclusion
  • When I reviewed Groove's TR­808 MIDI retrofit I suggested they might be the saviours of the universe, and nothing about the MIDI-2-CV causes me to change my mind. Groove on!

  • Chris Jenkins
  • Groove Electronics:(0722)743712