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Slim Phatty User’s Manual - The Components
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Slim Phatty User’s Manual - The Components
TECH NOTES:
1. The SP’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, a 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 Enve-
lope Generators (EGs).
The Slim Phatty has two identical EG circuits. When triggered, these circuits
produce time-varying control voltages having a start, a middle and an end.
The parameters that specify this progression are the Attack, Decay, Sustain
and Release controls, abbreviated as ADSR.
Attack determines the fade-in of the envelope. The Attack control adjusts
the time it takes for the envelope to go from zero to full value (in other
words, the fade-in time) when the EG is triggered. After the Attack segment
completes, the Decay control takes over, adjusting the second stage in the
evolution. Decay is the time that it takes for the signal to drop from the full
level to the level set by the Sustain control. Once the sustain level is reached,
it will remain there as long as the trigger signal is present. When the trigger
is finally released, the Release control determines how long it takes for the
envelope to return to zero (see the ADSR Envelope Signal).
The Slim Phatty has two envelope generators; one EG is dedicated to
the amplifier (to control the volume), and one EG is dedicated to the
filter (to control the cutoff frequency). The Filter EG can also be used
as a modulation source through the Modulation Matrix.
