MIDI
The first major technological shift came with the invention of the Musical Instrument Digital Interface, or MIDI for short. MIDI was, and still is, a way for musical instruments to communicate via computers, and it set a standard language for musical performance control. The world of MIDI is predominantly for keyboard-style instruments, but alternate instruments have been explored.
Player pianos read long sheets of paper with perforations punched out that correspond to pitches, and the piano interprets that information into music with automated key presses. In the computer age, the long rolls of paper are replaced by programming and computer control.
MIDI is simply a computer language that controls the playing of a musical instrument. Since the keyboard is just sending messages saying what note to play, when to stop, and how loud to play it, there is now the possibility of letting the computer do the same work by transmitting the information directly into the keyboard. Not only is MIDI a language, it is also a hardware connection, via a five-pin connection that allows all computers and MIDI-capable instruments to connect universally, much like the universal serial bus (USB) does for modern computers.
Once computers were able to control synthesized sounds, prerecording and editing became possible. Now, in combination with a computer, you can slowly play a difficult part from the keyboard and have the computer record your movements. After you are done playing the part, you can go back and fix mistakes, change tempos, and change pitches. It's now possible to use the computer as a recording and editing controller, and then have it play back the sounds through the synthesizer, at any speed. Lavish multipart orchestrations by one performer are now possible because the performer can simply push a button and have the computer play back twenty or more tracks at once.
The Guitar's Role
Keyboard players were having a lot of fun, especially in the early 1980s, with the invention of MIDI. Because all synths used the keyboard-style interface, piano players were able to unlock the world of computer music, while other instruments were left in the dust. This is not to say that guitar was left out of the synth game altogether. In the early days of analog synth, there were many successful guitar synths.
The first guitar synths started to enter the market in the late 1970s. Because of how analog synthesis works, the guitar was a good candidate to act as a synth controller. The string's vibration could easily be converted to voltage and sent through the synth engine. Early guitar synths were marketed by Roland and ARP. These guitars had a vast array of sounds, but few musicians really unlocked their secrets. The most successful analog guitar synth playing came from Pat Metheny, Adrian Belew (King Crimson), and Andy Summers (The Police). The guitar was very successful as a synth controller, but the advent of MIDI complicated life for the guitar player.
Complications
There are two factors that make a keyboard-style instrument a good synth controller: (1) The keyboard makes it very easy for the synth to determine what note you're playing, because each key has its own sensor, and a computer easily deciphers its messages; and (2) keyboard notes are either on or off and rarely have much nuance. Because of these factors, the keyboard has been the most successful of all MIDI controller instruments. When the synthesizers relied on pitch to voltage, the guitar did a nice job because that's what normal electric guitars do—they transfer the string's vibration to an electric charge via the magnetic pickups. When MIDI took over, things got very complicated for guitarists.
In order to detect what note you were playing, the guitar synth units had to analyze the waveform you played to detect a pitch. It took at least two full cycles through the waveform to detect pitch. On a keyboard, analysis could be done instantaneously, but on guitar synths it was delayed. Because of the differences in pitch on the guitar, lower strings took longer to play than higher ones due to differences in pitch and frequency. While the delay was measured in milliseconds, it spelled big trouble for guitar players. You played a note and the unit took awhile to catch up.
Guitar is an instrument filled with expression and nuance. Slides, vibrato, and bends further confused early MIDI guitars and caused headaches for the players. With technological advances, guitar synth has improved, but the technology still relies on figuring out what you're playing and converting it to MIDI data. And no matter how fast the machine is, there's still a delay—although it's much better now. While computers have gotten faster, the delay is still present. Present-day units are very useable, but don't expect them to respond exactly like a guitar. To this day, Roland, one of the first guitar-synth makers, has been producing guitar synths since the late 1970s. Other companies that manufacture synths are Yamaha, Axon, and Shadow. Modern guitar synths attach to your guitar with a small hex pickup that senses the sound and feeds it to the synth box for translation.
Forget about string bends—early MIDI units couldn't handle them. To get MIDI to work, you either had to play very slowly or have the cleanest technique ever, with no bends or slides to confuse the unit. Because of these quirks and difficulties, guitar synths have never really caught on, unlike the keyboard-style synths.
Workable Synths
The current MIDI technology for use with guitars has its limitations; if you've ever tried to rip a fast line on a guitar synth, you may remember feeling slightly displaced as the unit couldn't quite keep up. Several attempts have been made to approach the problem from a different angle. The two synths that have utilized different technology are the Synthaxe and the Ztar.
The Synthaxe was introduced in 1984 and was the brainchild of British designer Bill Aitken. What made the Synthaxe so different was that instead of relying on MIDI to analyze pitch, the fingerboard was wired to detect where you were playing. The strings on the fingerboard were dummy strings and made no sound; they only aided in making the guitar player feel at home on the neck. The dummy strings also detected pitch bend and vibrato information. Because the neck could sense where you were, there was no lag or delay in the process of playing; you could play quite fast. There was a second set of strings on the body that you could pick, and these strings sensed your volume. There were also buttons for triggering strings and samples from the body of the instrument, and a breath controller for blowing note volumes with breath. One catch: this perfect MIDI system capable of controlling any MIDI sound source or computer cost about $20,000!
With the invention of the Synthaxe, guitar players for the first time could play with guitar technique and make the sound of a trumpet come out, or piano, or whatever you wanted. Interaction with the computer was near perfect, too, but the price tag puts it largely out of reach for most players. Its most notable player is Allan Holdsworth, who plays so fast and clean on it you won't believe what you're hearing. The company went under and there are few left in the world.
In 1992, Starr Labs of San Diego, California, designed the Ztar, a unique guitar synthesizer controller. The Synthaxe fingerboard system worked well, but had many small parts and was hard to service and maintain. The Ztar set out to emulate the only true MIDI controller: the keyboard. Instead of strings, the fingerboard is laid out with pressure sensitive keys just like a piano—one key for each fret (6 × 24 = 144 keys) and each key is responsible for one note. There are no delays with this system, and no strings either. Since the buttons are small raised keys, they emulate the feeling of strings, so the dummy strings aren't necessary.
Unlike other guitar synths the Ztar can play multiple notes per “string,” something no real stringed instrument can ever do. This makes two-handed playing on the fingerboard an accessible technique.
On the body, the Ztar has an impressive number of options for playing, with either trigger bars or real strings for picking. Breath control is an option; joystick and computer readout is standard. The Ztar plugs into any MIDI interface, sound module, or computer via a standard five-pin MIDI cable. The Ztar is still produced today in several models and options, and remains the most drastic alternative to the current pitch-to-MIDI solutions on the market. The Ztar is, most notably, used by Stanley Jordan. I used the Ztar, myself, to compose the examples in this book and notate them on the computer via Sibelius notation software.
Guitar Synth Uses
As a live performance tool, a guitar synth can enable you to unlock sounds never before possible. You can play a string orchestra behind a soft ballad, and a piano part is now possible even if you don't have a keyboard player in the band. You can use it for an expressive lead sound (à la Pat Metheny), or it can be a great tool for composing music. With the aid of a computer, a guitar synth is the ultimate link between the computer world and the guitar world. Without guitar synth, you would have a hard time utilizing the exciting world of MIDI and computer music.
