MODBOX MKII

The Modbox MKII is a dual modulation oscillator featuring:

• ThreePhase LFO — Three outputs with controllable waveform, frequency and phase spread, plus a phase-modulation mode where each output modulates the phase of the next

• Skew LFO — Morphable saw/triangle/ramp waveform. When clock-synced it locks to the tempo as a beat divider/multiplier.

• Sample & Hold — Digital S&H with multiple operating modes

• Analog Noise — White noise source

The panel silkscreen uses a few label conventions worth knowing — the same terms are used throughout the manual.

Mode buttons (3Φ Mode, S&H Mode): each button cycles three modes, and the outline around each mode's label mirrors that mode's LED, so you can match a label to the LED at a glance:

• Regular label — mode 1 (LED off).

• Stroked (outlined) label — mode 2 (LED bright).

• Dotted border label — mode 3 (LED breathing).

The S&H pattern-length markings (1–32) sit inside a dotted circle — a reminder that pattern length applies only in the Turing Machine mode (S&H mode 3), whose label carries the same dotted border. The dotted styling also matches that mode's breathing LED, so the panel, the label, and the LED all line up. See loop length.

The lock icons around the S&H mode are just a reminder that the sequence can lock into a repeating loop in the Turing Machine mode.

Knob labels: each knob shows two functions.

• Bold name — the knob's main (primary) function.

• Italic name — its shift function. See Shift Functionality.

The ThreePhase LFO produces three outputs with controllable waveform, frequency and phase spread, plus a phase-modulation mode where each output modulates the phase of the next. Cycle modes by tapping the 3Φ Mode button.

• Spread (Phase Offset): Starts at full CCW with all three outputs in phase. Turning CW sweeps the phase offset from 0° to 360°, spreading symmetrically (out2 = −offset, out3 = +offset). Maximum spread (±180°) occurs at the 50% knob position; full CW wraps back to in-phase (360° = 0°).

• Phase Mod: Unipolar control over a phase-modulation cascade — each output modulates the phase of the next (output 1 → output 2 → output 3). Full CCW produces no modulation (outputs identical); full CW produces the maximum cascade, building progressively more complex, harmonically related shapes down the chain.

• Frequency Spread: Linear 1–8× range. Full CCW puts all outputs at the same frequency and phase; full CW runs output 2 at 8× and output 3 at 1/8× the base frequency.

The three modes at a glance — each diagram shows the three outputs (OUT 1, OUT 2, OUT 3) over the same span of time:

The 3Φ Wave knob morphs continuously between waveforms, with a dead zone around each pure waveshape that makes them easy to find:

• Full CCW: Saw

• ~10 o'clock: Pure sine (dead zone, centered)

• ~2 o'clock: Pure triangle (dead zone)

• Full CW: Ramp

When the Skew LFO is clock-synced (clock mode SKEW or BOTH), the Skew Freq knob stops acting as a free-running frequency control and becomes a beat divider/multiplier, locking the Skew waveform to the clock tempo. In this beat-synced mode the Skew LFO runs at musical divisions of the incoming clock — a different approach from the clock sync on a traditional LFO.

The Skew Freq knob sweeps across six anchor ratios relative to the clock:

/8    /4    /2    x1    x2    x4
└─────┴─────┴─────┴─────┴─────┘
 full CCW            full CW

Unlike the synced Freq clock ratios (which jump between 15 discrete integer steps), the Skew LFO crossfades continuously between adjacent anchor ratios as the knob turns. Internally it blends a primary ratio with a secondary one octave higher (2× the primary), weighted by the knob's position within the zone:

• At a zone center the output is purely that anchor ratio.

• Turning toward the next ratio smoothly morphs the waveform up an octave.

The result is a smooth, sweepable tempo-locked rate that is full of sweet spots with interesting modulations, rather than hard-switched divisions.

The Skew Freq CV jack offsets the ratio selection (±5V maps to roughly ±5 anchor steps). Because the offset is summed with the knob before the morph is computed, CV can smoothly push the Skew LFO across ratio-zone boundaries — including continuous octave-style sweeps under CV control.

When the ratio or clock tempo changes, the Skew LFO re-aligns its phase to the expected clock position:

• Large misalignment (>~40%): snaps immediately (a jump is imperceptible at that error).

• Small-to-moderate misalignment: corrects gradually over several control cycles for a glitch-free realignment.

• Tiny error (<~0.5%): ignored as noise.

Any phase offset set with the Skew shift function (Skew Freq knob during shift) is honored by the Skew LFO, and the Skew Shape curve still shapes the waveform as normal.

If the clock cable is unplugged while the Skew LFO is beat-synced, it holds the last-known tempo and keeps running. Ratio changes on the Skew Freq knob still work against that remembered tempo, so you can keep dividing/multiplying the last clock rate without a cable patched.

Unplugging the cable does not turn sync off. To go back to a free-running LFO — where the Skew Freq knob sets frequency directly — hold Clock/Reset to set the clock sync mode to NONE.

While shift is held, the Skew Freq knob becomes the phase offset control, so the beat ratio is frozen at its current value during shift (it does not jump as you turn the knob). The ratio resumes following the knob when shift is released.

This offset applies whether or not the Skew LFO is clock-synced. When it is free-running, the phase offset sets where the waveform restarts from when a Reset is received.

The Sample & Hold is a digital S&H with multiple operating modes. Cycle modes by tapping the S&H Mode button.

The S&H signal in jack is normalled to the module's internal analog noise — the same source as the Noise out jack. With nothing patched, every trigger samples a fresh random voltage (classic random sample & hold). Patching any signal into S&H signal in breaks that normal and samples your signal instead.

How each mode shapes the output — the input, trigger, or gate is shown on top, with the resulting output below:

• A clock/trigger patched into the SMPL jack drives sampling.

• With no cable in the SMPL jack, the trigger is normalled to the Skew LFO valley — the S&H samples once per Skew cycle at the analog low point of the wave.

• The SMPL button triggers a manual sample (tap).

• Mode 1 & 2 (S&H / Track & Hold): Sets slew/glide time, from ~0.1 ms (full CCW, near-instant) to ~1.07 s (full CW), exponential response. The knob has no Shift function in these modes.

• Mode 3 (Turing Machine): Sets the probability that steps repeat. At center a new value is picked on every trigger; turning clockwise raises the chance a step repeats, until fully CW the sequence locks into a loop. Counter-clockwise does the same but inverts the output voltages. In this mode Shift sets the loop length, 1–32 steps (see table below).

Shift is active only in Mode 3. Holding S&H Mode (shift) enters loop-length edit mode for the Turing sequencer:

• The Slew / Prob knob sets the loop length while held, from 1 to 32 steps.

• The sequence keeps playing during editing, advancing on each SMPL jack trigger (buffer content stays frozen). Shrinking the length wraps smoothly without clicks.

• The SMPL button is inactive while shift is held (the ButtonManager tracks one active button at a time) — the expected workflow is a clock patched into the SMPL jack while adjusting loop length.

The diagram below labels every control on the panel — each knob, button, and jack. The tables in the following subsections give the full detail.

• Tap 3Φ Mode to cycle ThreePhase modes (1→2→3→1).

• Tap S&H Mode to cycle Sample & Hold modes (1→2→3→1).

Cycle modes by holding the Clock/Reset button. Clock signals are patched into the dedicated CLK jack. Modes can be cycled with or without a cable: when no cable is present, the current LFO frequency becomes a "virtual clock" that the freq knob divides/multiplies.

Cycle modes by tapping the Clock/Reset button. Reset triggers are patched into the dedicated RESET jack.

When synced, the Freq knobs select from 15 symmetric integer clock ratios:

/8  /7  /6  /5  /4  /3  /2  x1  x2  x3  x4  x5  x6  x7  x8
                            ^
                        12 o'clock
                        (x1 dead zone)

The Freq CV jack provides V/Oct control: ~10 octaves over the knob range, freely multiplying/dividing the base frequency in free-running mode (no clamping), and offsetting ratio selection when synced. There is no dead zone around 0V.

1. Patch the clock signal to the CLK jack.

2. Hold Clock/Reset to cycle to the desired clock sync mode.

3. Use the Freq knob to select the clock ratio (/8 … x8).

1. Patch a trigger to the RESET jack.

2. Tap Clock/Reset to cycle to the desired reset mode.

3. The selected LFO(s) reset to 0° phase on each trigger.

Holding either the 3Φ Mode or S&H Mode button (500ms or more) enables the shift functions for both LFOs at once. While the button is held, certain knobs control alternate parameters.

Each knob's shift function is labeled in italics on the panel.

1. Hold 3Φ Mode or S&H Mode.

2. Move the desired knob past its entry position (takeup).

3. Adjust to the desired value.

4. Release the button (values are saved to memory ~60 seconds after the last change).

When you hold or release the shift button, knobs use "takeup" detection to prevent value jumps:

1. The knob's position is recorded when mode changes.

2. The knob must return near that position before the new function activates.

3. This ensures smooth transitions without parameter jumps.

If a knob is already at its entry position, takeup engages immediately.

The 3Φ Spread and 3Φ Wave knobs, while shift is held, use the same 15 symmetric integer clock ratios as the synced Freq knob:

/8  /7  /6  /5  /4  /3  /2  x1  x2  x3  x4  x5  x6  x7  x8
                            ^
                        12 o'clock
                        (dead zone, default = unity)

• 12 o'clock (x1): Unity — output runs at same frequency as output 1 (default; a dead zone around unity makes it easy to find)

• Full CCW (/8): Output runs at 1/8 the master frequency

• Full CW (x8): Output runs at 8x the master frequency

The Freq CV jack offsets the selected ratio (V/Oct).

The three ThreePhase outputs share a single output level that you can attenuate to best suit your musical purpose — turn it down for gentler, more subtle modulation, or leave it at full for the strongest effect. To set it:

1. Hold 3Φ Mode (or S&H Mode).

2. Turn 3Φ Freq: full CCW = silent, full CW = unity.

3. At full CCW (silent) the 3Φ LEDs flash "WMD" in Morse to confirm the outputs are off.

Holding both mode (shift) buttons together (500ms or more) enters a dedicated output-range mode. While both are held, all other shift edits are suspended and the Freq knobs set each oscillator's output range independently:

• Only the ends of each Freq knob set the range: turn fully CCW for BIPOLAR, fully CW for UNIPOLAR. Anywhere in between leaves the current setting unchanged.

• Each oscillator's range is independent and saved to memory.

• Default is BIPOLAR for both oscillators.

• When set to UNIPOLAR, a level of 0 (via 3Φ shift LEVEL) still outputs a clean 0V.

To set it: hold both mode (shift) buttons together (500ms or more), then turn 3Φ Freq (for the 3Φ oscillator) or Skew Freq (for Skew) into the lower 25% (BIPOLAR) or upper 25% (UNIPOLAR).

To reset all shift parameters to defaults: hold a mode button past the 500ms shift threshold, then press the Clock/Reset button.

• Resets shift settings: 3Φ level → full, output ranges → BIPOLAR, phase offsets → 0°, freq ratios → x1.

• Operating modes are preserved (3Φ mode, S&H mode, clock mode, reset mode are untouched).

To reset operating modes and shift parameters to defaults: hold both mode buttons for half a second, then press the Clock/Reset button.

• Resets operating modes: 3P mode → Mode 1 (Spread), S&H mode → Mode 1 (SAMPLE_HOLD), clock mode → NONE, reset mode → NONE.

• Also resets every shift setting listed above.

Each sync LED reflects its own oscillator's combined clock + reset state — Left = ThreePhase, Right = Skew:

Placeholder — the designer's note will go here.