Music Sound

A guitar/synthesizer (also guitar synthesizer, guitar/synth, or guitar synth) is any one of a number of systems originally conceived to allow a guitar player to play synthesizers. MIDI guitar is often used as a synonym for the field of guitar/synthesis or for a guitar/synthesizer, but MIDI is not involved in every case.

Traditionally, synthesizers have a keyboard interface to allow a human to play the instrument, but the human interface does not necessarily need to be a keyboard, nor indeed is any human interface necessary. (See sound module.) Because synthesizers generate sounds electronically, they can theoretically be actuated by almost any sort of input device. A guitar/synthesizer provides an interface which is familiar to a guitarist.

There are two main types of guitar/synthesizer: those which are real guitars outfitted with additional gear to actuate a synthesizer, and those which are guitar-like MIDI controllers. Both types have their advantages and disadvantages.

There is a growing trend by manufacturers of effects units to market so-called guitar/synth pedals. These effects use a variety of techniques to make a guitar sound more like a synthesizer, but they aren't really guitar/synthesizers.

Contents 1 Guitar-based guitar/synthesizers 2 Guitar-like MIDI controllers 3 Guitar/Synthesis 4 Prominent guitar/synthesizer players

Guitar-based guitar/synthesizers

The earliest guitar/synthesizers were based on actual guitars. Roland Corporation has been and remains a significant proponent for this paradigm of guitar synthesis. Other notable manufacturers include Axon and Yamaha Corporation. Guitar/synths in this category are the most popular, and consist of the following components:

• A guitar. The guitar is usually an electric guitar, but may also be an acoustic guitar.
• A hexaphonic pickup (also called a divided pickup), which provides six distinct outputs, one for each string.
• A converter, which determines the pitch coming from each of the strings and transmits this information to a synthesizer.
• A synthesizer, which generates the intended note.

These components may be integrated or modularized in different ways.

The hexaphonic pickup may be a separate component which can be mounted on almost any guitar, or it may be built into the guitar as original equipment. The earliest guitar/synths required the musician to use a proprietary guitar, which was designed with an integrated hexaphonic pickup. Roland later developed its GK line of pickups which allowed the pickup to be mounted onto any guitar. Today, several guitar manufacturers offer their guitar models with integrated Roland hardware. These are called "Roland-ready".

Usually, a cable connects the hexaphonic pickup to the converter. This allows the guitarist some freedom of movement, unencumbered by the converter. However, several Casio models in the PG and MG product lines integrated the guitar, the hex pickup, and the converter into one unit. Casio remains the only manufacturer to try this approach. It was convenient in that a MIDI cable could be plugged directly into the guitar.

The converter may be a standalone unit or it may be integrated with a synthesizer. The earliest models integrated the converter and the synthesizer. Some models still do. The earliest integrated models predated the MIDI standard, so the guitarist was stuck with whatever synthesizer was integrated with the converter. Today's integrated models include MIDI output. Standalone converter units drive synthesizers via MIDI.

The chief advantages of this type of system are:

• The timbres of the guitar and synthesizer can be blended together at any ratio, enabling the musician to play guitar alone, guitar and synthesizer, or synthesizer alone.
• In many models, almost any guitar can be used.

The chief disadvantages of this type of system are:

• At lower pitches, there is a detectable latency between playing a note on the guitar and the same note sounding on the synthesizer. This latency has diminished as designs have improved.
• All the variable performance parameters available on a synthesizer cannot be actuated on a guitar. While a guitarist can control pitch and volume directly from the guitar, a guitar lacks assignable controls to open a filter in real-time, for example. Contemporary guitar/synth designs often include an expression pedal for this purpose.
• Tracking of notes is often prone to glitches. This can be mitigated by properly adjusting the pickup, properly adjusting the converter's sensitivity controls, and by playing more precisely.

Guitar-like MIDI controllers

Some manufacturers of guitar/synthesizers wanted to eliminate the tracking and latency problems associated with guitar-based systems, while retaining the expressiveness of the guitar. They achieved this to some degree by redesigning the human part of the interface so that it was better suited to driving a synthesizer. A variety of technologies were tried.

A well-known guitar-like controller produced in the 1980's was called SynthAxe. It was a futuristic controller consisting of a fretboard attached to the body at an obtuse angle. The fretboard strings were used to indicate pitch and sensed string bends. A separate, shorter set of strings were used for picking and strumming. These triggered the notes fretted on the fretboard's strings. It also featured trigger keys which could be used instead of the trigger strings. A whammy bar was assignable to any MIDI parameter. The SynthAxe was prohibitively expensive.

Yamaha originally entered into the market with a guitar-like MIDI controller called the G-10. It was considerably less expensive than the SynthAxe, though still out of reach for many musicians. The G-10 featured two assignable knobs and an assignable whammy bar. It had just 6 strings, all the same gauge, which sensed both right- and left-hand input.

Both the SynthAxe and Yamaha G-10 were later discontinued.

Starr Labs' Ztar is the only remaining guitar-like controller product line still in production. A Ztar differs significantly from the SynthAxe and Yamaha G-10 in that the "fretboard" is covered with keys, not strings. Keys in the same row can trigger notes at the same time. This has no analog on a real guitar. It would be as if a single string were polyphonic.

The chief advantages of the guitar-like MIDI controller systems are:

• Tracking is much better than guitar-based systems.
• There is no noticeable latency.
• Whammy bars and other controllers could be assigned to any MIDI function.

The chief disadvantages are:

• The controller is not a guitar. It does not make guitar sounds nor does it feel exactly like a guitar.
• Expense

Guitar/Synthesis

It is difficult to say whether a guitar/synthesizer is an instrument in its own right. The Roland paradigm is actually two instruments, one controlling the other. Guitar-like MIDI controllers are not instruments at all; just an interface to the instrument. Nevertheless, guitar/synthesis has its own techniques, advantages and limitations which are distinct from both guitar playing and conventional keyboard synthesizers.

Not all guitar playing techniques can be translated into MIDI. Harmonics, palm mutes, hammer-ons, pull-offs, pick slides, etc. all have no analog in the world of synthesizers. Similarly, guitars have no means to vary all the parameters which may be available on a keyboard synthesizer. Guitars, unless they are fretless, cannot do portamento, for example.

Hence, playing a guitar/synthesizer means, in some ways, accepting the least common denominator between the two instruments. However, controlling a synthesizer with a guitar has some advantages over a keyboard. More expansive chords are possible, and some intervals are easier to reach.

Guitarists have a few reasons for using guitar/synthesizers:

• Guitar/synthesizers provide access to a vast array of sounds normally available only to keyboard players and percussionists. A guitar player could take on a flute part, for example. This makes a guitar player more versatile.
• The guitarist can create a hybrid timbre which is recognizable neither as a guitar nor a synthesizer.
• A guitarist with limited or no keyboard playing skills can program a sequencer.

Prominent guitar/synthesizer players

A number of guitarists have done significant work with guitar/synthesizers. Many are either jazz, progressive rock, or fusion guitarists.

Adrian Belew
Amir Derakh
Robert Fripp
Reeves Gabrels
Chuck Hammer
Allan Holdsworth
Al Di Meola
Phil Keaggy
Alex Lifeson
Pat Metheny
Jimmy Page
Lee Ritenour
Mike Rutherford
Neal Schon
Tom Delonge
Andy Summers