Le Caine began
work on this instrument between 1952 and 1954 at his home studio.
He brought the prototype organ to the National Research Council
lab in 1954 and considerable development took place over the next
prototype of the Touch Sensitive Organ.
The Touch Sensitive
Organ was modelled after the traditional pipe organ in its timbre
and its concept. The timbres were all pre-set and operated by
stops as in a traditional organ. Organ keys, unlike piano keys,
are operated as switches which turn the notes on and off, but
provide no control of volume.
In the Touch
Sensitive Organ, Le Caine extended the touch-sensitive volume
control of the Sackbut to the polyphonic keyboard. Independent
volume control for each key considerably expanded the musical
ability of the electronic organ.
In addition to the
touch-sensitive keyboard, Le Caine also devised a technique to avoid
the "click" sound that had previously been part of the
attack of the notes of all electronic organs.
- The 1954 Prototype
- The Keyboard
- Diagrams &
- The Commercial
The 1954 Prototype
Le Caine demonstrating the prototype of the Touch Sensitive Organ
in 1954 (on the right is a bank of vacuum tube oscillators; to
its left is a screen on which the waveforms generated by the instrument
can be examined).
Under each touch-sensitive
key were five electrodes, each of which was wired to a sound generator.
The result was a great deal of wiring.
mechanism of the Touch Sensitive Organ.
The keys of the
Touch Sensitive Organ were spring-mounted to provide resistance
to the performer. As the key was pressed lower, the electrodes
attached to the bottom of each key came into closer proximity
with the fixed electrodes below the keyboard, thus increasing
the current transferred and the volume of the sound. By varying
finger pressure, Le Caine could control both the volume of a note
and its attack, gradual or percussive. He used the touch sensitivity
to highlight a melodic line, to accent a ryhthmic structure and
to provide independance to the many parts of a contrapuntal piece.
view of the keyboard mechanism from above.
The Touch Sensitive
Organ had 99 generators, one for each note of the keyboard. All
of them could sound simultaneously. Le Caine played the instrument
with a sustaining pedal and a device that could shift the pitch
to provide vibrato and wide glissando.
A Schematic of
the Touch Sensitive Organ.
shows the relation between pressure on the key and perceived
volume of the sound at two different settings. The (a) curve
shows a more gradual attack while the (b) curve shows a more
sudden or percussive attack.
shows three possible sensitivity settings for the
touch-sensitive keyboard. The most vertical curve shows a
setting where the greatest volume results from the lightest
pressure--translated here into the depth to which the key moves
attacks available on a touch-sensitive key range from sudden percussive
sounds to a gradual onset. These oscillograms show two possible
attacks produced using this keyboard, controlled by the speed
with which the key is depressed.
The last model
of the Touch Sensitive Organ, built in 1956, was designed to take
advantage of techniques already learned by pianists. The name
"Touch Sensitive Organ" was replaced by "Touch
Sensitive Keyboard." In 1956 the Baldwin Organ Company bought
the rights to the touch-sensitive keyboard. This was the result
of Le Caine's demonstration of the keyboard at the 1955 Trade
Fair. In 1956 the NRC development of the instrument ceased.