STURDY STUDIO-WARE

One of the first things you notice about the unit is its sturdy construction. Although it may lack the polish of mass produced Japanese studio-ware, it has a solidity about it, probably due to the fact that the units are assembled by hand. The front panel has a heavy metal ring on either end, which makes pulling it out of your rack easier. From left to right on the front panel, there are eight grey circular buttons labelled A to H, each with an LED above it. Further inspection reveals that these eight buttons are sub-divided into three categories: A selects the mode of operation, B to D the parameter, and E to H set parameter values. Four buttons to programme values? Unfortunately, the M4CV forces you to use binary numbers all the time.

Further to the right are four more LEDs numbered 1 to 4, and these simply indicate which of the four synths is currently selected. Underneath these LEDs are 12 small holes which allow access to trim pots, three per synth (Tune, Scale and Bend). These enable the user to calibrate the unit's outputs so as to generate notes on the slaved monosynths that are in tune, and track pitch properly. The third pot sets pitch bend sensitivity, and a large black knob to the right turns the pitch bend on or off. To the rear of the unit we find no less than 14 mini-jacks: three per synth for Control Voltage, Gate, and Level (the Level output should be connected to a synth's filter control input, if it has one); the two remaining jacks are the ARP clock output, and an 'S' trigger output which is dedicated to synth number one. It is an alternative to the standard Gate output, enabling synths with an 'S' type Gate, such as Moogs, to be controlled. Finally, there is a Sync-24 socket (or DIN sync as it is alternatively known), and MIDI In and Thru sockets, all 5-pin DIN connections.

I had two complaints regarding the outputs. Firstly the mini-jack inputs are recessed behind drilled holes in the casing — nothing wrong with that of course, because it gives stability to the plugs should they get pulled — but the holes are a little small, so some brands of plug may be a bit of a squeeze (I found that Tandy pre-moulded miniplugs fitted the best). The second gripe concerns the labelling of the outputs; these are simply hand-typed pieces of sticky label, which rather detracts from the unit's cosmetic appeal. Maybe I'm being picky — after all, who sees the back once it's in a rack — but if a manufacturer has gone to the trouble of having the front panel printed, then why not do the whole thing properly?

SETTING UP

I wasn't really expecting there to be much preparation required for using a piece of kit like this. On reflection, I think this probably heightened the trauma that opening the manual induced. Remember binary numbers? Yes, that's right — those strings of 1s and 0s that most of us decided we didn't need to learn about in maths. Well, they reappear with a vengeance here. The procedure for selecting a numeric parameter on the M4CV is to specify it in binary form using the E, F, G and H LEDs. A lit LED represents a 1, and an unlit LED represents a 0.

It isn't really quite as bad as it looks at first, as the manual explains everything properly, but it's best to take your time and work through the procedure slowly. Just to reassure you, here is an outline of the basic set-up principles. The button marked A (or Mode) steps through the four basic operational modes, and its LED tells you which mode you are currently in by its status (on, off, flashing slowly, flashing quickly). The different modes are: Recall Mode; Select Mode; Synth Select; Edit Mode.

Recall Mode allows you to select memorised set-up configurations; up to 16 of these may be stored at once. Select Mode allows you to specify how you want the M4CV to operate (Mono, Poly or Simms). These three options configure the unit to drive four monosynths independently from four MIDI channels, or four monosynths in 4-voice polyphonic mode from a single channel, or to act as a MIDI-to-drum convertor to trigger Simmons brains. In this latter role, the 12 CV and Gate outputs are split into two groups of six, and you must allocate a MIDI note number to each. In Synth Select mode you can select which of the four synth channels you want to edit, and you then enter Edit Mode to select parameters and actually make the changes. Parameters are selected using the B, C and D buttons, and depending on what mode you are in, they give access to MIDI channel numbers, Key Priority (New, Low or High), and Trigger Type, (-Ve, Gnd, and +Ve).

As I mentioned earlier, there is a dedicated 'S' trigger output on the rear, and so if you are using this facility, it would not be necessary to select a trigger type — all you do is plug straight into the 'S' trigger socket instead of the usual Gate output for synth 1. The M4CV cannot drive synths which use the Hertz-per-Volt system (as found on early Yamaha synths, see box) in its standard form. Groove Electronics can, however, provide linear control convertors as an optional extra. As for control of the ARP and Sync-24 clocks, you can choose either to send a MIDI start signal before the first pulse of the clock or at the same time. This is particularly useful as some older drum machines and sequencers read the MIDI Start signal as being the first clock pulse, and this can lead to timing errors. The ARP clock can be set to different clock rates, and you can choose whether its output voltage swings from high to low or vice-versa.

"The bottom line is that the M4CV is damn good at its job, converting up to four channels of MIDI into Control Voltage and Gate signals fast enough to keep your music together."

IN USE

I set up the M4CV to receive MIDI data from my Atari ST, and control my three analogue synths, a task it performed with consumate ease. None of the three have filter inputs, so I couldn't control filter cut-off via MIDI. For synths that do, the filter can be controlled by several types of controller data: breath controller; aftertouch; modulation wheel; velocity. (Incidentally, Groove can fit most popular monosynths with filter inputs.) I had to tweak the tuning and scale trimpots a few times just to get the tuning spot on, but aside from this there were no problems. Besides the synths, I was also running a TR909 drum machine from the Sync-24 output, and an ancient Soundmaster drum box from the ARP socket. The TR909 ran perfectly, although the Soundmaster was a little temperamental — more likely a problem with the Soundmaster's ancient circuitry than with the M4CV.

I wasn't able to track down a full 12 Simmons brains to test the alternative Simms mode, but I did manage to scrounge five from a colleague, and I am happy to report that they responded very well to the Groove unit's control.

CONCLUSION

I can remember Groove Electronics back in the mid-80s, when their box ads offered no more than straightforward clock convertors and the like. A lot of water has passed under the bridge since those days, and Groove now offer a range of innovative MIDI products. The M4CV is a particularly good unit, which could undoubtedly be a big seller in its field, but it does have one or two faults. Firstly, the user interface leaves a lot of room for improvement — the current system is not a good one, but at least once you have programmed the unit to suit your set-up you shouldn't have to do it again. The rear panel's aesthetic shortcomings are hardly critical, and although the manual is only a 17-page photocopy, it is by and large adequate as long as you take your time to read it properly.

The bottom line is that the M4CV is damn good at its job, especially when you consider what that involves: converting up to four channels of MIDI data (in Mono mode) into Control Voltage and Gate signals in a fraction of a second, fast enough to keep your music together. This is no mean feat. Add to this the fact that it has ARP and Sync-24 outputs as standard, and that it doubles as a MIDI-to-drum controller, and you simply have to concede that the M4CV is well worth the asking price — recommended!

FURTHER INFORMATION

£275 inc VAT.

Groove Electronics, (Contact Details).