by the Noise Quality switch (H), labelled WHITE/PINK. As an
audio signal, the Noise Source may be fed into the mixer by
turning on switch (F). As a control signal, it is available
through the Modulation Mix, as described in Section G.
J. MODIFIERS
The Modifiers section of the front panel features controls for
the two sound modifiers, the Filter and the Loudness Contour, which
respectively shape the overtone content and loudness/time contour
of the audio signal as it passes through the modifying circuitry from
the mixer. In order to hear the effect of these controls, begin by sett-
ing the controls in the oscillator and mixer sections as follows:
Control S e t t i n g
Oscillator MODULATION SWITCH (A) o f f
Oscillator 1 RANGE (4) 1 6 ’
Oscillator 1 WAVEFORM (5) narrow rectangular
(extreme right)
Oscillator 1 VOLUME (12) 7
Oscillator 1 MIXER switch (C) o n
Other mixer switches (D, E, F, G) o f f
Switches (J) (K) (L) o f f
The controls on the Modifiers section should still be set as shown
in Fig. 1 of Section D.
FILTER
The Mini Moog features a wide-range lowpass filter. This filter
attenuates, or cuts out, those frequency components of an audio signal
which lie above a variable cutoff frequency, while passing those
components which lie below it.
1 ) The CUTOFF FREQUENCY control (17) is used to set the filter’s
cutoff frequency. Hold down a key and turn this control first
clockwise, then counter-clockwise. You will hear the tone become
more shrill and then more muted, as the higher overtones are first
allowed to pass and then attenuated. If control (17) is moved all
the way to the left, the entire signal will be cut out.
2 ) The AMOUNT OF CONTOUR control (19) determines the amount of
filter contour applied to the filter’s cutoff frequency. Each time
a key is depressed, a contour generator attached to the filter is
actuated, and sends a control signal to the filter. The control
signal rises at one rate, then falls at a second rate, and finally
levels off at a certain level. This results in a corresponding
rise, fall, and leveling off of the filter cutoff frequency,
which we call the "filter contour."
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