The LGE026 combines an analog amplitude/ring modulator and voltage comparator for versatile audio processing, control voltage manipulation, and logic generation in 4U Serge Modular systems.

The Low-Gain Electronics LGE026 AM/RM + Comparator combines two versatile analog signal-processing functions in a compact 4U modular synthesizer module: an amplitude/ring modulator and a voltage comparator. The upper section features an AD633-based four-quadrant analog multiplier capable of amplitude modulation (AM) and balanced ring modulation (RM). Two incoming signals can be multiplied together to produce a wide range of effects, from conventional amplitude modulation and tremolo to complex harmonic and inharmonic sidebands, metallic textures, and bell-like tones.

In Ring Modulation mode, the circuit functions as a balanced modulator, multiplying the two incoming signals while ideally suppressing their original frequency components. In Amplitude Modulation mode, an additional signal component is introduced into the multiplier's output, with a dedicated CAR/MOD switch allowing either input to be selected for this purpose. The modulator input features a bipolar attenuverter, allowing the incoming signal to be continuously adjusted from inverted through zero to non-inverted. This provides control over modulation depth and polarity, expanding the range of available sounds and modulation behaviors. Beyond conventional audio processing, the DC-coupled four-quadrant multiplier can also be used for manipulating control voltages, making it useful for creating complex modulation relationships between oscillators, envelopes, LFOs, and other voltage sources.

The lower section features an independent voltage comparator with positive and negative inputs and an adjustable bipolar threshold. The comparator converts changing analog voltages into discrete logic states, making it useful for level detection, gate generation, pulse-width modulation, waveform conversion, and audio-rate logic processing.

Together, these two circuits offer a flexible combination of audio processing, voltage multiplication, and analog-to-logic conversion in a single module. Designed for 4U Serge-format modular synthesizer systems, the LGE026 is equally suited to traditional Serge patching techniques and experimental analog signal processing.

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