A couple of years ago it seemed that the world was still waiting for a guitar synthesiser that was truly useable; this has arguably now been achieved, and the new challenge is that of designing guitar to MIDI converters that are compatible with any guitar. Use of a conventional guitar to control a synth, as opposed to using something like the Synthaxe, is always going to create certain problems. These include triggering delays and possibly less then perfect tracking, but for a lot of people these problems are tolerable when compensated for by the fact that they can use a conventional guitar, and thus have access to familiar guitar sounds.

The IVL Pitchrider 7000 is a guitar to MIDI interface which allows any guitar to generate MIDI signals and thus control a synthesiser. The system consists of a hexaphonic pickup, which mounts on the guitar, and a rackmounted controller which converts the information to MIDI. Guitar to MIDI converters for use with any guitar are fairly rare, and this factor is seen as a major selling point; balanced against this is the possible difficulty in attaining accurate tracking on some models.

The hexaphonic pickup is a fairly narrow unit which is fixed to the body by means of double sided sticky tape. The design is rather like a guitar bridge, in that it is supported on two posts of adjustable height, and the main bar of the pickup has six ridges which contain the sensing element for each string. The pickup comes in two widths in order to accommodate different string spacings, and this main bar is actually slightly flexible so that it may be shaped to match the curvature of the strings.

Positioning of the pickup is quite critical, in that each element of the pickup needs to be as close as possible to the relevant string without actually impeding its movement, and the pickup is designed to be positioned as close as possible to the bridge. Ideally the guitar to be used as the controller should have space for the pickup between the bridge and the existing first pickup, and it should obviously have as even a response as possible. On the review model the pickup was fitted to an ESP Strat derivative. Apart from having the new pickup stuck to it, there's no modification required to the guitar. A small box hangs from the guitar strap button; two captive leads connect it to the hexaphonic pickup, and the standard guitar jack socket. A socket on the box accepts the seven pin DIN lead which connects it to the control unit.

The main control unit is 1U rack mounting; the review model had a separate power unit, but future models will have an integral power supply. There's just one socket on the front, the seven pin DIN which accepts the guitar lead. Round the back there's a single MIDI out, the standard guitar output, and a footswitch socket.

The control panel is split into three sections. From the left, the first section contains one click-action switch and six LEDs, one for each string. In normal use the LEDs light whenever the relevant string is triggered. When programming any setting the switch may be used to step through all the strings, so that they may each be transposed by different amounts, or sent to a different MIDI channel, for example.

The second section, Setting, enables various values to be entered for any of the various modes selected; it consists of a standard dual eight-element LED display, which should provide reasonable visibility under stage conditions, and increase and decrease click-action switches. The actual parameters which these switches are used to alter are selected by means of the Mode selector of the third section.

When switched on, the unit is in play mode; pressing the Mode switch will then select each programming mode sequentially, with an LED to indicate which one is selected. Six programming modes may be selected; the first is for MIDI channel, which may be defined separately for each string. Pitch bend, the second mode, may be set between 0 and 12 semitones. Transpose mode enables individual or all strings to be transposed by up to 12 semitones up or down, a somewhat stingy capability; two or three octaves would be useful. Volume dynamics mode selects how much 'velocity' information is sent to the synth, and maybe set to a value between 0 and 9. The last two modes are for setting input sensitivity, which selects a threshold below which strings vibrations are ignored, and overall tuning, which maybe set between A=400 and A=460Hz. Use of combinations of switches may program the function of the footswitch, which will either mute the MIDI output, or switch through the programmes on the synth used.

When you switch the unit on, nick the five pin DIN lead from your hi-fi to connect up the faithful DX7, and attempt to set up the sensitivity. The first emotion experienced by the unsuspecting guitar-synth operative is one of impotent rage, but perhaps that's being a bit mild. The reason for this is that the MIDI output is muted when the programming mode is engaged, thus you can't setup the input sensitivity and hear the result at the same time. This applies to all the other programming modes as well, and selecting volume dynamics is just as annoying; for the other modes it isn't so serious, but just to add insult to injury, all the settings are lost when the unit is switched off. This obviously means you have to reset the sensitivity every time you use the unit.

Tracking of guitar signals is reasonable; the triggering delay is fairly short, at least as good as most of the competition. Consistency of triggering, however, is less than staggering, and quite a lot of adjustment is required to playing style — this isn't helped by the fact that you can't adjust the sensitivity of each string individually, a strange omission. Pitch following in pitchbend mode is also somewhat erratic; hammer-on's, for instance, will sometimes be followed properly, at other times the pitch of the synth makes a half-hearted attempt to follow that of the guitar, and then gives up. As pitch bend mode does place certain restrictions on how to play, it would be handy to select it remotely; unfortunately this isn't possible, and it's actually pretty time-consuming switching through programming modes to get to the right one. Furthermore, there's no triggering mode available whereby you can cancel the release phase of one note by playing another note on the same string — if you think about it, that's the way any conventional string instrument would work.

IVL have actually set themselves quite a difficult task in designing a unit that will work with different guitars. It doesn't seem to be this factor, however, that causes the apparent shortcomings. The tracking achieved is good, but would be much better if you could adjust the sensitivity separately for each string — otherwise there's no way you could cater properly for different string gauges and picking strengths. It seems inexplicable to go to the trouble of designing a pickup scanning system and then leave out an element which will have such a significant effect on the final performance.

On a system which is designed to work with any guitar it would be reasonable to expect a few shortcomings. What seems less forgivable are those omissions in terms of programming options, which in a few cases could be eliminated by means of software changes. As it is, the IVL system places too many restrictions on playing speed and technique to satisfy the guitarist, and too many restrictions on programming options to satisfy the synthesist.

IVL Pitchrider 7000 Guitar to MIDI Converter - RRP £999