Moog Music Little Phatty Stage II - Manual (Page 13)

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LP Stage II User’s Manual - The Components
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LP Stage II User’s Manual - The Components
TECH NOTES:
1. The LP’s Overload circuit uses asymmetrical clipping, which clips each side of the waveform
differently. Asymmetrical clipping circuits tend to produce tones with unique richness and character.
2. The Overload circuit has no effect on the sound when the analog edit control is set fully counter-
clockwise. Advancing the control gradually introduces the effect, starting with a gentle overdrive-like
quality that becomes increasingly aggressive and edgy as the control reaches 100%. Because the
Overload uses clipping, some sounds, such as a square wave with the filter cutoff all the way up,
aren’t affected much by increasing the Overload amount. Try sounds tuned to intervals other than
unison, and a slightly resonant filter setting to really hear the effect.
3. The name “Overload” came from the Overload indicator on the Minimoog, where if the output
was patched back into the audio input the Overload indicator would go on. Mixing the Audio in
would provide a “fatter” sound by increasing the level of signal coming out of the mixer and going
into the filter.
C. The Envelope Generators Section
Musical sounds have a start, middle and an end. For example, a plucked string sound starts with an initial
burst of energy and then slowly fades out until it is silent. In synthesis terms, this progression is called an
envelope – a shape that defines the changes that occur in a sound over time. An envelope can define any
aspect of change in a sound – volume, timbre, or pitch. The circuits that create envelope control signals in
synthesizers are called Envelope Generators (EGs).
The Little Phatty has two identical EG circuits. When trig-
gered, these circuits produce time-varying control voltages
having a start, middle and an end. The parameters that
specify this progression are the Attack, Decay, Sustain and
Release controls, sometimes abbreviated as ADSR.
Attack determines the character of the onset of the sound.
The Attack control adjusts the time it takes when a key is
pressed for the envelope to go from 0 to full value (the
fade-in time). The Decay control adjusts the second stage
in the evolution of a sound before it sustains or dies out.
Decay is the time that it takes for the signal to drop from
the full level to the level set by the Sustain control. The
envelope will stay at the sustain level as long as a key is held
down. When the key is released, the Release control de-
termines how long it takes for the sound to fade out (see
ADSR Envelope Signal below).
The Little Phatty has one EG dedicated to the filter (to control
the cutoff frequency), and one EG dedicated to the amplifier
(to control the volume). The Filter EG can also be used as a
modulation source through the Modulation Matrix.