Overview
The F355 packs two LFOs into a compact 2FU module, each generating over 10,000 waveforms via wavetable morphing. Rate ranges from one cycle every 12 minutes to audio-rate at 1000Hz. Runs on a 24 MHz 32-bit ARM processor with minimal frequency drift.
LFO Synchronization Modes
The F355’s two LFOs can be “locked” together in three different configurations, selected via a panel switch:
Mode 1 - Independent Rates: LFO1 and LFO2 run at different speeds while maintaining identical waveshape and phase. Useful for creating polyrhythmic modulation where the same gesture repeats at different tempos.
Mode 2 - Independent Waveshapes: LFO2 shares the same rate and phase as LFO1 but outputs a different waveform. Creates synchronized modulation with varying timbral characteristics.
Mode 3 - Phase Offset: Both LFOs output the same rate and waveshape, but LFO2’s phase can be offset from 0° to 360° relative to LFO1. Produces stereo-like modulation effects and complex interference patterns.
LFO1 functions as the “master,” always retaining independent control over rate, FM, and morphing parameters. Both LFOs track 1V/octave for musical tuning and respond to voltage control across all parameters. Visual feedback comes from two LEDs that display output amplitude across 128 brightness levels.
Morphing Engine
The F355 shares its morphing engine with the acclaimed E350 Morphing Terrarium. Rather than abruptly switching between waveforms, the module calculates 4096 intermediate waves between stored wavetables.
Waveform Banks
Three distinct banks provide different sonic territories:
Bank A - Classic Waveforms
Basic waves arranged by increasing harmonic complexity: sine, triangle, sawtooth up, sawtooth down, pulse waves at 25%, 50%, and 75% duty cycles, plus noise. These form the foundation palette for traditional modulation.
Bank B - Harmonic Multipliers
Takes the waves from Bank A and repeats them at higher frequencies—1x, 2x, 3x, 4x, up to 8x. This multiplication expands the LFOs’ operational range, allowing vast rate differences between the two outputs. At higher frequencies, the F355 functions as a basic audio oscillator, limited to 1kHz but useful for sub-bass tones and low-frequency drones.
Bank C - Robert Rich Collection
Features 64 exotic waveforms created by composer Robert Rich, drawn from Bank C of the E350 Morphing Terrarium. This bank ventures into experimental territory: arpeggiated sequences, note patterns, pings, swoops, and lattice phase modulation effects. When pushed into audio range, these waves produce harsh, noisy, crunchy timbres—far removed from conventional LFO output.
External Control
Two external inputs extend the module’s functionality:
Sync Input - Hard-resets the LFO phase to the start of its cycle, allowing rhythmic synchronization to external clocks or triggers.
Freeze Input - Holds the LFO output at its current voltage level, suspending waveform progression. Useful for creating sample-and-hold effects or freezing modulation at specific points.
