Harmonic Processors

The Harmonic Processors are based on the Serge Wave Multipliers module and offers three unique, voltage-controllable wave-shaping circuits that dramatically enhance harmonic content and timbre.

Harmonic Processors (Wave Multipliers) Module –
This module is based on the classic Serge Wave Multipliers.

Overview
Traditional analog synthesizer patches often follow a linear signal path: VCO → VCF → VCA, with modulation via keyboard, sequencer, or computer. While the VCO generates the sound, the VCF alters timbre through subtractive filtering, and the VCA shapes amplitude and dynamics.

The Harmonic Processors introduce a new element into this chain, offering additive, non-linear wave shaping for richer, harmonically complex timbres. Placed before the VCF, this module doesn't filter out frequencies—it adds harmonics and transforms waveforms in dynamic, controllable ways. Unlike ring modulation, this process works with a single audio input and yields results that are uniquely expressive.

There are three independent wave multiplier circuits in this module, each offering different sonic capabilities. Together, they form a powerful toolset for generating timbres previously limited to acoustic instruments or complex digital processing.

Functionality
Top Section – Dual Mode Distortion / VCA
HI Mode: Applies soft, voltage-controllable waveform clipping, akin to overdriving a tube amp—rounded, saturated distortion rather than hard-edged clipping.

LO Mode: Functions as a linear VCA, ideal for amplitude modulation and gating into other sections of the module.

Middle Section – Odd Harmonic Sweeper
Generates odd harmonics (1st to 13th) by processing an input sine wave.

CV or manual sweep controls harmonic content—comparable to overblowing a wind instrument.

Includes a second input for mixing two signals before processing, yielding complex, evolving textures beyond traditional ring modulation.

Bottom Section – Even Harmonic Wavefolder
Uses three cascaded full-wave rectifiers to shape and double input frequencies.

Adds even harmonics (2nd, 4th, 8th, etc.) while maintaining output amplitude.

Produces smooth timbral transitions and rich sonorities.

Dual inputs and dual outputs, including a squared-up variant similar to advanced PWM.

Sound Design Potential
The Harmonic Processors (Wave Multipliers) enable radical timbral modification that far exceeds conventional analog capabilities. These modules deliver a level of harmonic complexity and expressiveness typically associated with acoustic instruments. Precise control voltage response ensures both creative flexibility and technical reliability, whether you're building chaotic textures or fine-tuned tones.

** 4U Modular is a term used for the format most commonly known as “Serge Format” or “Loudest Warning Format”. Out of respect for the ever growing format, 4U Modular is the easiest way to refer to it. More Specifically it refers to the panel height and mounting hole style. 4U Modular will patch up just fine with other 4U "Serge" formats such as "Random Source", but it will not mount in RS boats or Buchla Boats (or power off Buchla power for that matter). An info page about this will be added to the website soon to make this a lot more easy to understand.

https://www.low-gain.com/shop/p/lge113