Download Multimoog Musical Instrument Technical data

Now we can route control signals into the con
trol input of each module shown above to dynami
cally control its function. Think of a control signal fed
into the control input as acting like an invisible hand
that turns the knob for you. Voltage controlled
modules are sometimes referred to with letters, such
as VCO (voltage controlled oscillator), VCF (voltage
controlled filter), and VCA (voltage controlled
amplifier). Although any number of modules may be
voltage controlled, these are the most common—
VCO, VCF, VCA.
Anything that makes a proper signal that is
connected to a control input is defined as a controller.
On a modular synthesizer, the output of a controller
would be connected to the control input of a module
with a patchcord as shown:
CONTROLLER—CONTROL INPUT CONNECTION
VCO
VCF
VCA
TO
MONITOR
CONTROLLER
CONTROLLER
J
On the Multimoog, control signals may be
connected to control inputs using a variety of
switches and selectors. Or a control signal from the
outside world might be routed through the FILTER or
OSC A&B INPUT on the rear panel. Each control input
on the Multimoog is capable of adding all of the
voltages that are applied from several controllers;
that is, control voltages are additive.
A keyboard is a controller that makes discrete
voltage steps which increase as you play up the key
board. If this controller is connected to the control
input of the VCO, the keyboard can be used to
control the pitch of the VCO and tunes can be played.
Harmon mute. As you move your hand away from the
A contour generator is a controller that creates
a rising and falling voltage pattern, a contour. If we
connect this controller to the control input of the
"triggered.")
VCA, the amount of amplification (silence to
maximum) will be controlled. This lets us articulate
the sound.
The VCF can also be controlled by a contour
generator. When this occurs, the tone color will typi
cally become brighter as the contour voltage rises,
and duller as it falls. To get back to our comparison
with the trumpet, suppose that you were using a
26
CONTROLLER
plunger in the center of the mute, you create the
familiar "wow" or "wah-wah" effect. Your hand is
acting as a contour generator, controlling the filter
(mute).
Of course, we have to tell a contour generator
when to start and stop creating contours. For this
purpose, the synthesizer produces another type of
signal called a "trigger." The keyboard generates a
trigger signal that tells when a key is depressed and
released—useful information. A trigger is a timing
signal that "triggers" the contour generator(s). (On
some modular equipment, other functions can be
I n summary, the modern synthesizer consists of
several elements: sound sources, modifiers, control
lers, and trigger sources. Sound sources make audio
signals that can be heard. Modifiers alter signals. Con
trollers make signals used to control sound sources
and/or modifiers. Triggers are timing signals that
usually initiate the action of a controller such as a
contour generator. See below for a block diagram of
the basic voltage controlled synthesizer.