Ferry Island Modular Undertow
Two wavetable LFO/VCOs feeding a 5x3 morphing modulation matrix — 15 simultaneous CV outputs.
16 HP Eurorack module
Undertow is a 16HP two-dimensional modulation system from Ferry Island Modular. Two wavetable oscillators sit on either side of the panel and morph into each other across a 5x3 grid of jacks. The horizontal axis is a waveform/frequency morph from 100% Left → 50/50 → 100% Right; the vertical axis adds modulation that gets progressively more turbulent toward the top. That gives you fifteen related-but-distinct bipolar CV outputs from one patch, plus end-of-cycle triggers on both sides for rhythmic patching. Each side has its own waveform, frequency, wavetable bank, clock input, and CV attenuation. Open-source firmware, I2C expansion, designed and built in Finland.
Features
- 5x3 matrix of fifteen simultaneous bipolar CV outputs with per-jack LEDs
- Two independent wavetable oscillators (LFO or VCO) with five wavetable banks each
- Horizontal axis morphs waveform and frequency between left and right sides
- Vertical axis adds selectable modulation (Mod Type) at scalable depth (Mod Amount)
- End-of-cycle trigger output on both sides for rhythmic patching
- Clock inputs on both sides — divide/multiply when clocked, or V/oct when frequency attenuator is fully open
- Five wavetable banks per side with dedicated Bank L/R buttons
- I2C input and output headers for expansion
- Open-source firmware with wavetable updates
- 16HP wide, 40mm deep
- Designed and built in Finland
Controls & Jacks (37)
- Clock In L — Clock or V/oct input for the left side. Clock drives rhythmic modulation per row; with Freq L Atten fully up, accepts V/oct for VCO behavior
- Clock In R — Clock or V/oct input for the right side.
- Matrix Out R1 100L
- Matrix Out R1 Col 2
- Matrix Out R1 50/50
- Matrix Out R1 Col 4
- Matrix Out R1 100R
- Matrix Out R2 100L
- Matrix Out R2 Col 2
- Matrix Out R2 50/50
- Matrix Out R2 Col 4
- Matrix Out R2 100R
- Matrix Out R3 100L
- Matrix Out R3 Col 2
- Matrix Out R3 50/50
- Matrix Out R3 Col 4
- Matrix Out R3 100R
- EOC L — End-of-cycle trigger from the left oscillator. Fires at the start of each new cycle.
- EOC R — End-of-cycle trigger from the right oscillator.
- Mix Out 100L
- Mix Out 50/50
- Mix Out 100R
- Wave L CV In — CV input modulating the left side's wavetable position (after the Wave L Atten attenuverter).
- Wave R CV In — CV input modulating the right side's wavetable position.
- Mod Type — Selects the type of modulation applied to the vertical axis — different shapes produce clean-to-turbulent character.
- Freq R Atten — Attenuverter for the right frequency CV input. Full CW enables 1V/oct tracking for VCO use.
- Wave R Atten — Attenuverter for the Wave R CV input.
- Freq L — Sets the frequency of the left oscillator. Acts as a clock divider/multiplier when Clock In L is patched. When the Freq L Atten is fully ope
- Freq R — Sets the frequency of the right oscillator. Acts as a clock divider/multiplier when Clock In R is patched; tracks V/oct when Freq R Atten is
- Mod Amount — Scales the modulation depth applied along the vertical axis. Bottom row stays clean; higher rows receive progressively more modulation.
- Wave L — Selects waveform from the left side's current wavetable bank. Sweeps continuously through wavetable positions.
- Wave R — Selects waveform from the right side's current wavetable bank.
- Bank L — Cycles through five wavetable banks for the left oscillator.
- Bank R — Cycles through five wavetable banks for the right oscillator.
- Freq L Atten — Attenuverter for left frequency CV. Full CW puts the left side into V/oct tracking mode for VCO use.
- Mod Atten — Attenuverter for the modulation amount CV input.
- Wave L Atten — Attenuverter for external CV modulating the left side's wavetable position.
How-To Guides
- Fifteen Related LFOs From One Patch
- Wavetable VCO Mode
- Clocked Rhythmic Modulation
- Audio-Rate Chaos
Explore the interactive Undertow panel on BleepDex — tap any control to learn what it does.
