Musical sounds are rarely static. They are constantly being shaped and changed by the musician. A musical instrument provides the means for varying sound, whereas the sound of a particular musician is related to his technique for controlling his instrument.
Keyboards are used as control devices on a wide variety of musical instruments. In using a keyboard instrument, a musician is not in intimate contact with the instrument’s vibrating element (as he is when he plays a guitar, for instance). However, he does gain rapidity of access, because the modern keyboard is nearly perfectly fitted to our hands. Rapid, precise playing of streams of notes is accomplished more easily on keyboards than on any other type of pitched instruments.
The Synthesizer Keyboard
Continuing our celebration of 40 years of Keyboard, we present Bob Moog’s second “On Synthesizers” column from our November/December 1975 issue, in its entirety. Synthesizer keyboards provide a means of control over sound that is basically different than that of acoustic keyboard instruments. All synthesizer keyboards produce two types of electrical signals: A pitch control and a trigger. The pitch control-signal tells which key is being depressed, which the trigger tells when a key is depressed. If the pitch control is used to change the pitch of an audio generator and the trigger is used to turn the tone on and off, we would have a “one-note organ.”
Of course, modern synthesizers are far more than one-note organs, and much of the reason for this can be found in the way synthesizer keyboards and auxiliary control devices have developed within the past ten years or so. Two features of early synthesizer keyboards have now become standard functions: Memory, and keyboard glide. By memory, we mean the ability of the keyboard circuit to remember, or hold, the pitch control-signal of the last key to be depressed.
These two features alone cast the keyboard in an entirely new musical light. No longer is the familiar keyboard primarily a means of turning sound off and on. Now it is used to shape single sounds. In fact, the “pitch control-signal” doesn’t even have to be used to control just pitch. By applying this same signal to control a filter, a musician uses a keyboard to change tone color as well as pitch.
Early synthesizer designers also developed several auxiliary controllers—devices that can be used alone or in conjunction with the keyboard to impart additional nuance to synthesizer tones. Such devices as the ribbon controller and the touch-sensitive plate were first explored by many musicians during the middle and late ’60s. The ribbon controller is a taut metal band which is played much like the fingerboard of a string instrument. The touch-sensitive plate responds to the position of the player’s hands on a plate’s surface. And where no other controllers were available, early synthesists “played” control knobs, thus developing synthesizer playing technique into a both-hands involvement with every aspect of the sound for which there was some sort of control.
Modern performance synthesizers provide keyboard glide and memory as standard features, and many include one or more auxiliary controllers. Popular auxiliary controllers include the center-detent pitch-bender control and the pedal of the ARP Odyssey, and the modulation wheel and pitch-bender ribbon of the Micromoog. I think of these auxiliary controllers as extensions of the keyboard, in that they enable the musician to augment the expressive content of his music with the motions of his hands.
The Touch-Sensitive Keyboard
Throughout the history of keyboard instruments, there have been important examples of keyboard actions that have allowed the musician to do more than simply start and stop notes. Three instruments immediately come in mind: The tracker organ, the clavichord, and the piano. In the tracker organ, each key is linked directly to the valves that control the airflow to that key’s pipes. By pressing a key gradually, a tracker organist imparts a soft attack to the note. When he hits a key hard, the note’s attack is fast, often with a “chiff” (extra short burst of a high harmonic). In the clavichord, each key is linked to a wedge that actuates the string by bearing against it. When a clavichordist presses a key hard, he stretches the string, thereby raising its pitch. Skilled clavichord players actually impart vibrato to the string’s tones. Finally, the piano action is an amazingly sensitive mechanism for enabling the musician to control dynamics by how hard he hits a key. Although the tracker organ and the clavichord have been around for hundreds of years, their unique modes of keyboard control continue to interest musicians today. And, of course, the piano is currently the most popular acoustic keyboard instrument.
In a synthesizer, touch-sensitive mechanisms can be used to control a wide variety of musical parameters. The most popular touch-sensitive controller is the type used in the Yamaha Solo Synthesizer or the ARP Pro Soloist. In these instruments, the touch sensor determines how far down the key is. The touch sensor signal increases as a key is depressed. This signal is used to continuously control variables such as brightness, vibrato, loudness, even pitch. With this type of touch sensitivity, the synthesist can simulate the control modes of many acoustic instruments (the violinist’s continuously changing vibrato or the trumpet player’s crescendo, for instance). More important, however, he can explore totally new ways of controlling musical nuance.
Three standard elements of synthesizer keyboards—memory and keyboard glide, the auxiliary controllers, and keyboard touch sensors—have all added significant new musical dimensions to the standard keyboard. Together, these new features are a large part of the excitement of modern synthesizers.