Moog Mother-32 - Mother-32 Overview; Analog Synthesizer Signal Path; Sound Sources; Sound Modifiers

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MOTHER-32 OVERVIEW
The Mother-32 is a semi-modular analog synthesizer. Each function has been designed as a module,
and useful parts of each module are “pre-wired” on the internal circuit board for making sound. This
means that your Mother-32 will produce sound at its output without any patch cables in use. Extended
synthesis capabilities are easily accessible via the 32-point, 3.5mm patchbay.
ANALOG SYNTHESIZER SIGNAL PATH
SOUND SOURCES
In an analog synthesizer, circuits that generate small electrical vibrations can be used as sound
sources. The Mother-32 contains one Voltage Controlled Oscillator (VCO) and one White Noise
generator, which are internally wired as sound sources. A VCO is a circuit capable of producing
a steady tone, which can be made to go up or down in pitch by applying a Control Voltage (CV)
to its circuit. A White Noise circuit amplies naturally occurring electronic noise to make the
same type of sound you might hear on a radio tuned in between stations.
The outputs of the VCO and Noise source are routed to a Mixer (MIX) so the two signals can be
blended. Note that the NOISE output is “normalled” to the EXT. AUDIO input jack. This means that,
with nothing plugged into this jack, White Noise is the signal blended with the VCO. By plugging
an external sound source into the EXT. AUDIO input, the White Noise signal is replaced with the
external signal. This allows you to blend the VCO with any sound source you like on the Mother-32.
The output of the Mixer then goes to the input of the Voltage Controlled Filter (VCF).
SOUND MODIFIERS
Mother-32 operates on the principle of subtractive synthesis. To make a musical electronic sound,
you start with a bright, harmonically-rich signal, then circuits called lters and ampliers are used to
transform the original signal into the desired sound. The Mother-32 contains both a Voltage Controlled
Filter (VCF) and a Voltage Controlled Amplier (VCA).
In an analog synthesizer, a lter is a circuit used to modify a sound source by making it darker,
brighter, or even thinner based on its type, frequency response and lter cutoff frequency. The
Mother-32 features the classic Moog Ladder Filter topology, with both Low Pass and High Pass
frequency responses available. Low Pass means that the Filter removes high frequencies above the
Cutoff frequency from the input signal, while High Pass means the Filter removes low frequencies
below the Cutoff frequency. In both cases, the CUTOFF control sets the specic frequency for the
Filter circuit to start working. In LOW PASS mode, the RESONANCE control is used to feed the
VCF output signal back to its input, creating a peak in the frequency response at the Filter Cutoff
frequency. This can be used to emphasize the harmonics in a sound source by sweeping the Filter
Cutoff frequency. The output of the VCF then goes to the input of the VCA.
In an analog synthesizer, an amplier is a circuit that can change the loudness of a signal. The
Mother-32 VCA can be set to ON, continuously passing the output of the VCF straight through
to the instrument’s output, or it can be controlled musically from a circuit called an Envelope
Generator (EG), which creates a control shape (contour) from a trigger source such as a key
being played on a keyboard or a MIDI Note.
The output of the VCA passes to the VOLUME control, which attenuates the output signal at
both the VCA output and the HEADPHONE/AUDIO output.
VCO
NOISE
KB/
SEQ
EXT
AUD IN
MIXER
VCA
LFO
VCF
EG