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Serge VCM
SERGE
Wave Multipliers
(VCM) for Eurorack
The legendary Serge Wave Multipliers (VCM) are a module - or rather 3 modules - designed to dynamically add
new harmonically-related overtones to an input waveform. Accroding to the 1982 catalogue, they “alter the
timbre in exciting new ways, producing interesting alternative forms of signal processing which are unique in the
Serge Modular Music System. Since there are three entirely separate and different types of Wave Multipliers in
this module, an enormously varied palette of new effects can be synthesized.”
The top section offers two different modes, selected by a switch. In the “HI” position, the module functions to
“square-up” an incoming signal, with a rounded attening of the signal peaks, somewhat similar to overdriving a
tube amplier (with voltage control!). In “LO” mode, the module is a linear gain controlled VCA. This is useful for
various functions such as amplitude modulation and for gating signals into the other sections.
The middle section generates a sweep of
the odd harmonics (1, 3, 5, 7, 9, 11 and
13th) when a sine wave is applied to its
input and the FOLD knob is turned up or a
control voltage is swept from low to high.
This effect is similar to overblowing a wind
pipe closed at one end. A second input is
included to allow two signals to be mixed
before processing. This module can be
used to explore timbral areas beyond the
range of ring modulation.
The bottom Wave Multiplier performs
non-linear wavehaping known as full-wave
rectication, but with sophisticated level-
compensating conditioning as well. The
circuit uses three full-wave rectier sec-
tions linked in a very rened controllable
format. Sweeping the VC input over its
range will produce a smooth timbral transi-
tion using the even harmonics (second, fourth, and eighth). Many other partials are present in this basic sound,
however, and the sonorities are very rich and varied. The white output is a “squared up” version of the black
one, resembling an harmonically enhanced pulse width modulation.
