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Shadow MIDI Guitar System


Article from International Musician & Recording World, September 1986

Who knows how good a MIDI add-on for your guitar can be? The Shadow knows, as Paul Trynka finds out....

After all those years when Roland were the sole bearers of the flame, we are at last seeing the resurgence of the guitar synthesiser elsewhere. The main reason for this is the advent of MIDI; now manufacturers may be sure that their controllers will be compatible with a wide range of synthesisers. For the consumer, this also has the advantage that buying a particular controller will not restrict them to a certain style of synth. Furthermore, you can now buy relatively affordable synths that actually have more range than a combination wah-wah and fuzz box, even if they're not as much fun to jump up and down on.

All the same, there aren't many guitarists seen using these objects, and a lot of those who do actually seem to have more interest in appearing technologically up to date than sounding good; an attitude rooted in two main objections: firstly that 'a keyboard controller will do anything that a guitar controller can'; and secondly that the inherent delays and restrictions on playing style demanded by guitar controllers make them less than useful. So how does The Shadow fare against these objections? We shall see...


The Shadow GTM 6 guitar-to-MIDI conversion system consists of a 2U rack unit costing £899 which contains the bulk of the conversion electronics, a hexaphonic guitar pickup built into its own bridge unit which for the strat version will set you back a further £151, and a three-pedal board which performs some basic control functions (included with the rack unit). I tried the Shadow with a Yamaha TX7 module, which seemed as likely a partner as any.

The guitar to which the pickup was fitted for review was a Squire '57 Strat; at the moment the Shadow pick-up and bridge can be fitted to any Strat-style guitar, a version for Ovations is under development, and other popular guitar designs will be included eventually. One of the strongest selling-points of this approach is that you can MIDI to an existing favourite guitar with a minimum of fuss — the operation can be carried out by any accredited Shadow dealer in a matter of hours.


The pickup system's fairly similar to that on Ovation electric/acoustics; with a separate piezo pickup for each string contained in each bridge saddle. The use of such a contact-based system is important in the final performance of the system, since it minimises resonances and cross-talk. The Shadow bridge looks like your average Strat tremolo bridge with fine tuners and nut-lock, and pivots around a fulcrum. There's no additional routing involved. Each of the six individual saddles contains a piezo element, and consequently they are quite solid, and sit directly on the tremolo plate. This means there's no adjustment for individual strings. The saddles are however graduated in height, and on the review model the action and intonation achieved was faultless. Changes to the tremolo action, and consequent changes in bridge height, would take quite a lot of work to accommodate, though, possibly requiring neck-shims. Intonation adjustments will similarly be quite tricky; so make sure, when you get one of these units fitted, that your dealer knows his stuff, and that the action achieved suits you.

Individual outputs from the pickups are multiplexed so they may be sent down a single line, and this signal, along with the standard guitar output, is sent via a stereo jack to the control unit. The normal guitar wiring is unaffected apart from the loss of one tone control, which is replaced by an 'acoustic' volume control. The extra circuitry is very well shielded and compact, and requires no enlargement of the control cavity.

Construction of the control unit is quite straightforward. There's a stereo jack input for the two guitar signals (your own guitar's pickups, and The Shadow's), and two jack outputs for the same at the back. One of these gives you the straight electric guitar sound, the other gives you the sound of the Shadow pickups, which is quite rounded and 'acoustic' in nature. There are two parallel MIDI sockets on the back for connection to your chosen synth. Round the front you'll find six small pots for adjusting individual string sensitivity, a perfectly adequate 2-digit LED which lets you know what the unit is up to, and a further, larger pot to set the overall dynamic range. The control panel's main functions are housed in a detachable keypad unit, allowing remote control of the unit's main parameters — providing you have the necessary multicore cable... (Shadow are, at the time of writing, sorting out their own version of it...)

A pedalboard's connected by means of a 5-pin Din on the front of the main unit, for control of the on-board sequencer(!), and a variety of other functions, as we shall see. For something that's going to get kicked around on the floor, though, I don't think a DIN connector is sufficiently reliable; for the extra tenner it would've cost, XLRs would have been a better bet.


If you're starting from scratch you'll need to program the tuning, and set the sensitivity for each string. If your synth responds to velocity information you can control this too, via the Dynamics pot. I won't bore you with the details, but suffice to say, the whole start-up procedure is dead easy. You can set the guitar to any pitch, so you're not restricted to A=440Hz, and furthermore you can check your tuning visually on the LED, (this means you can flog your guitar tuner!) MIDI channel selection is straightforward, and you can assign separate channels to each string. Individual or all strings may be transposed up to three octaves up or down by any number of semitones.

The pedalboard supplied with the unit has three main functions. The first pedal, Rec-Play/on-off will switch the synth sound on or off, and also controls the onboard sequencer; as basic as you can get, with no editing facilities, it has 1000 note storage in real time. It might be useful in some live situations, but for anything more advanced you'll have to buy a dedicated unit.

The Hold pedal if used with one synth will sustain one note or chord, and you may then solo over it with the straight guitar sound. With two synths, you may hold a chord on one, and solo over it with the second. In fact, altogether the Shadow will transmit on up to eight MIDI channels, one for each string, one for the sequencer, and one for the hold function.

The third pedal controls the chain function; it will step through selected presets on different MIDI channels if required, and will also step through the three pre-programmed Trigger options available. This means you can automatically change Trigger mode at the same time as synth voicings, a very useful feature, as we shall see...

Look No Glitches!

Using the same kind of patches that I normally play from a keyboard, it was quite exciting to find how much better a lot of them sounded being played on a guitar. Piano and organ voices admittedly take a lot of work, but stringed instruments come alive, sounding far better triggered from the Shadow than they would from a keyboard. This is due primarily to the way the triggering operates. There are three options for triggering modes on the system: Trigger, Quantize and Bend modes.

In Trigger mode, pitch changes of less than a semitone are ignored. When you reach the next semitone, the pitch changes and the envelope re-triggers. Quantize mode is fairly similar in that pitch changes of less than a semitone are ignored, but in this case, when the pitch changes the envelope doesn't re-trigger. In Bend mode the pitch of the synth follows exactly that of the guitar. There is a limitation here, however, because of the MIDI protocol; MIDI is designed primarily for keyboard instruments, and in general for a keyboard instrument pitch bend is achieved by means of a pitch bend wheel and affects all the notes being held at the time. On a guitar, however, it's possible to bend individual notes within a chord. MIDI doesn't allow this, unless you assign each guitar string to a separate synth; unfortunately, even multitimbral synths like the Casio CZ 3000 won't bend each voice separately. In the Shadow a compromise is effected; for monophonic playing pitch is followed continuously, otherwise the system defaults to trigger mode.

These different options might sound confusing; in fact, they give you a versatility that you just can't get from a keyboard. In practice you'd probably choose the mode according to the type of instrument you're imitating. Trigger mode is pretty similar to the way a keyboard controller would operate; the other modes actually offer more control than you'd get off a keyboard, because you can choose whether or not a note will re-trigger according to where you play it on the fretboard, ie whether you play the new note on the same or a different string. This is the kind of option you take for granted when playing a guitar or violin, but you try reproducing that on a keyboard!

The mode that you use also affects the dynamics you can obtain; In Trigger or Quantize mode, driving a velocity sensitive synth, you can obtain a very wide dynamic range. In pitch bend mode the obtainable dynamic range is not quite so great; it could roughly be described as the usable range obtainable from a non-weighted as opposed to a weighted keyboard.

The system produces no glitching whatsoever, with excellent pitch tracking. Harmonics also track consistently provided you keep your touch even, and there's no spurious triggering evident. Any playing style concessions to accommodate the triggering system seem minimal; when sensitivity is set to optimum only the very quietest passages may fail to trigger the unit. In fact, the main adjustment you have to make is to match your style to the voicing you're using — a creative 'problem' which takes more thought than any technical considerations.

Having said that, triggering delays do start to get noticeable when you get down to the lower two strings; the only solution to this is to transpose the converter an octave down, and play the required part an octave higher. In most cases the attack programmed in the chosen voice has just as significant an effect. It's therefore necessary to adjust your technique according to the voice used. This is something you wouldn't normally do on a guitar, but which keyboard players take for granted.


The Shadow GTM 6 is an impressive system on several counts; firstly it enables more of a choice as to the guitar controller, depending on the bridge design of the guitar in question.

The tracking capabilities really are superlative, probably because of the way the pickup is incorporated to the bridge. Speed of response is about as fast as you'll get with pitch to voltage conversion; the only way greater speed can be achieved is by moving to something like the Synthaxe, in which case you lose the straight guitar sound and are restricted to synthesised sounds only; you also look as if you're engaged in a wrestling match with a creature from another planet when you're playing the thing.

The Shadow is obviously up against some stiff competition, particularly the Ibanez unit, the Roland GK1, and perhaps the new IVL guitar pitchtracker (to be reviewed next month). The main factors to choose between them are price, the quality of the actual guitar used, and the accuracy in tracking available. It will be interesting to see how the Roland GK1 in particular, which is basically an add-on pickup, will compare with the Shadow in terms of tracking, because mounting the pickup in the bridge seems to offer the most problem-free solution to resonances and crosstalk.

These considerations are things you'll have to balance for yourself; what's certain is that guitar synthesis has at last overcome most of the technical difficulties, and the Shadow GTM 6 system is good evidence of this fact.

Shadow MIDI Guitar System - RRP: See Copy

Also featuring gear in this article

Previous Article in this issue

Tosco Rotocasts

Next article in this issue

Charvel 2B Bass

Publisher: International Musician & Recording World - Cover Publications Ltd, Northern & Shell Ltd.

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International Musician - Sep 1986

Gear in this article:

Guitar Synthesizer > Shadow > GTM-6

Review by Paul Trynka

Previous article in this issue:

> Tosco Rotocasts

Next article in this issue:

> Charvel 2B Bass

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