Continuum fingerboard

The continuum fingerboard (fig.1) is an electromechanical instrument of the controller synthesizer type.  From the traditional keyboard the instrument has only retained the keyboard pattern as an aid to the player. The surface is smooth, like the fingerboard of a violin, which enables the playing of all possible tones between the intervals of the chromatic tone scale. In this sense, the continuum fingerboard is more closely related to the ondes Martenot (see instrument of the month July 2013) than to the ordinary electric keyboard. Hence the instrument is sometimes called a fretless keyboard.

The continuum fingerboard is still handmade by its designer, Lippold Haken, a professor of Electrical and Computer Engineering at the University of Illinois. Haken developed the continuum in the mid-1980s, and first marketed it in 1999.

The musician places his fingers on a neoprene (synthetic rubber) playing surface, under which hundreds of little aluminium rods on springs are placed. At their ends these rods have an electromagnetic sensor that transmits the information (position, pressure, movement) formed by the fingers (fig.2).

This information is processed by a DSP (Digital Signal Processor) and converted to MIDI (Musical Instrument Digital Interface) data. Contrary to other MIDI master keyboards,the continuum needs a specific synthesizer to reproduce all technical playing variations. Consequently, since 2008, the instrument has been equipped with an internal modular synthesizer, the EaganMatrix, designed by Edmund Eagan, a friend of Lippold Haken’s. While, with an ordinary MIDI keyboard, a sound can only be started or stopped, with shades that are more or less touch sensitive, the continuum allows  the same complex playing as on any acoustic instrument.  

The sensors under the surface respond very precisely to the finger position and pressure in three dimensions: X, Y and Z. They provide pitch resolution of 0.1 cent (1 semitone = 100 cents) along the length of the scale (X), allowing continuous pitch control for portamento effects. The finger’s lateral position (Y) controls the timbre, with the vertical position (Z) determining the sound volume. In the course of playing a note can thus evolve in these three dimensions (fig.3).  Another application allows converting the trembling of the finger into vibrato, which is impossible on a keyboard, but very typical of violin and guitar playing. The continuum is capable of polyphonic performance, with up to 16 simultaneous voices.

According to Lippold Haken the continuum fingerboard, like any other instrument, needs many years of learning to master the necessary playing: ‘Most of the instrument’s expression does not come from the sound itself; rather, it comes from what you do with your fingers.’

Text: Matthieu Thonon