01_40_1
additional parameters: if1, if2, if3, iamp2, irate


Three oscillators are connected in a manner such as to form a
basic instrument with LFO control of pitch. 

The LFO function is variable and a few linear functions exemplify
how the pitch parameter can be managed in a continuous fashion.
The instrument gives one opportunities for any pitch envelopes
that one can imagine. These contours are scanned at the rate of
the LFO, which is irate times per note. In this design, irate is
duration dependent. Since it is an LFO, frequencies =< 20 Hz are
required. Above that limit begins the domain of FM.

For f32 and f33, the instrument 01_40_1 coincides with part 2 of
#100, see also 1_11_1.

One function leaves the frequency unmodified, while the other
function furnishes a frequency rise from 90% to 100%. This type
of design enables us to model subtle glissandos and to drive them
from within the score file by defining the pitch time function
for each note.

Next we display two other linear functions steering frequency.
F37 and f40 are selected from #511 (Glissandi with constant
frequency differences). Risset applied very long note durations
to this instrument. Also, the composer lets the glissandoing
sounds enter with ca. 1 sec delay from each other. This way the
tones follow the same pitch envelope, the pitch of the first tone
is ahead of the pitch of the second while their frequency
difference remains constant. We did not repeat the chase.

F38 descends two octaves, f39 ca. a sixth. (Risset 1969: #100,
Risset 1969: #511)

(flowchart)
(.orc and .sco files)

