Ferry Island Modular Undertow

Name: Undertow
Brand: Ferry Island Modular

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.