10
Now move the switch to the right. This selects, as a control
signal, the output of the LFO. Rotate the knob to the left; you
will hear the pitch rise and fall, further in each direction as
the knob is rotated further to the left. The rate (i.e. speed
or frequency) of this rise and fall is directly determined by
the frequency of the LFO itself; and you can change that with
the knob #9 in the diagram.
After you have experimented with this for a while, return the
controls to the settings of page five.
Now open the input from the noise generator; switch the VCF to
bandpass operation; set the resonance about one-third; and
raise the frequency of the VCF to about 1 o'clock position. You
should hear something like whistling wind.
The control voltage selector and attenuator for the VCF are in
section #5. Move the switch to the right, and the attenuator to
either right or left. The approximate "pitch" of the whistling
wind will rise and fall under control of the LFO.
NOTE: The VCF cannot generate signals of its own. It can only
change the balance of different frequency components present in
the audio signal given to it. When you change the VCF "fre-
quency" setting, either manually or by voltage control, you are
changing the "range" or "area" of particular frequencies that
are emphasized. Try using maximum resonance with a lowpitched
sawtooth input open only a little--about 10 o'clock--and manu-
ally sweeping the VCF frequency from bottom to top slowly. You
should be able to hear individual harmonics of the sawtooth
very easily. Return to the "whistling wind" setup for the next
step.
Now move the control selector switch to the left, providing ENV
2 as the control signal, and rotate the signal attenuator to
the right about halfway open (3 o'clock'position). Depress any
key on the keyboard, and hold it down. You will hear the area
of emphasized frequencies in the noise--the "whistling"--rise
and fall again. Continue these experiments with different set-
tings of the ENV 2 attack, decay, and sustain constants, until
you are thoroughly familiar with them. Then leave the settings
unchanged at the positions of the diagram on page five, while
you press a key repeatedly; each time lowering the VCF fre-
quency setting a little, and increasing the control signal
amplitude by rotating the knob a little further to the right.
Now try an oscillator signal instead of the noise generator
input signal. Drop the resonance to minimum and use the lowpass
mode. The settings you have now arrived it provide one way of
interrupting the continuous sounds you have been hearing up to
