F_TABLZ

F_TABLZ – Dual Wavetable Oscillator with DX-Style Phase Modulation

F_TABLZ is a dual wavetable oscillator designed for morphing timbres and DX-style phase modulation. It contains two oscillators (A and B), a 72-wave wavetable pool organized in banks, bandlimited mipmaps to reduce aliasing, stereo mixing/spreading, and a modulation index input so you can drive PM depth from an external envelope (classic “DX expression” behavior).

The module has two operating modes: NORMAL (both oscillators audible) and PM (B modulates A; you mainly hear A). The small waveform displays show the currently selected waves for A and B and reflect the effective shaping that’s applied (PURE/DX waves stay clean).

Important note about terminology: In this module, “PM” means phase modulation (DX-style). It is similar to FM in sound, but technically it modulates phase. The “PMOD / INDEX” controls determine how strongly OSC B modulates OSC A in PM mode.

Signal Architecture

• OSC A is the main oscillator (carrier).
• OSC B is the secondary oscillator. In NORMAL mode it is audible and can be mixed with A. In PM mode it becomes the modulator for A.
• BITE is feedback on OSC B only (a classic DX trick). It changes harmonic complexity and can get aggressive.
• SHAPE is a global waveshaping amount applied to the non-PURE banks. The PURE/DX bank is never shaped, so sine/tri/square remain stable and clean for FM/PM work.

Modes

MODE (switch)

• 0 = NORMAL: OSC A and OSC B are both audible. You can blend them with MIX and spread them in stereo with SPREAD.
• 1 = PM: OSC B phase-modulates OSC A (DX-style). Outputs are essentially OSC A (with optional pseudo-stereo). MIX is not relevant here.

Inputs and Outputs

V/OCT (input) – 1V/Oct pitch CV for OSC A. OSC B follows OSC A via RATIO and DETUNE.

FM (input) – Exponential FM input (treated as V/Oct style modulation). Amount is set by FM AMT and is bipolar.

MRPH (input) – Morph CV shared by both oscillators. It offsets MORPH and MORPH B together. Expected range is about 0..+5V (clamped internally).

RST (input) – Phase reset on rising edge. Resets both oscillators and clears feedback/envelope smoothing. Useful for consistent attacks, synced basses, and tight FM transients.

BITE CV (optional)

The BITE control can optionally be modulated via its dedicated CV input, allowing dynamic control over the internal feedback of OSC B. This is particularly powerful in PM mode, where OSC B functions as the modulator for OSC A. The BITE input expects approximately 0–5V. The incoming voltage is added to the current BITE knob setting and internally clamped for stability. Increasing BITE raises the feedback amount on OSC B, which results in brighter spectra, denser sidebands in PM mode, and increasingly metallic or noisy textures at higher values. Because BITE directly influences the internal feedback loop of OSC B, modulation can significantly alter the character of the sound. Slow modulation produces evolving harmonic movement, while faster modulation can introduce aggressive or unstable timbral behavior. For controlled FM-style tones, use moderate envelope amounts. For more experimental or percussive textures, combine higher BITE CV with elevated INDEX values in PM mode. Internal scaling ensures the feedback remains stable, but extreme settings will noticeably increase harmonic density.

PM (input) – External phase modulation input (audio-rate supported). Depth is set by PM AMT. This affects the phase readout of the oscillators (and therefore the waveform) in both modes.

RATIO (input) – Ratio CV for OSC B. Internally mapped musically as 1V per octave around the base ratio (0V = no change, +1V doubles ratio, -1V halves ratio).

ENV / IDX (input) – External envelope/expression input for PM index. This is meant to be driven by an ADSR or other modulation source. It can be 0..+5V or -5..+5V; the module clamps and smooths it.

OUT L / OUT R (outputs) – Stereo outputs.

Wave System (72 waves)

The wavetable pool contains 72 waves arranged in 9 banks of 8 waves each:

• Bank 0: SAW – bright saw-like families with spectral tilt variations.
• Bank 1: PULSE – hollow/pulse-like families with strong odd-harmonic emphasis.
• Bank 2: TRI/SINE – smoother families with steep harmonic rolloff.
• Bank 3: RESO – resonant/formant-like peaks that sweep across harmonics.
• Bank 4: METAL – comb-like harmonic selection for metallic tones.
• Bank 5: VOWEL – multi-peak formant shapes reminiscent of vowels.
• Bank 6: BUZZ – dense bright harmonic content and “buzzy” tilt.
• Bank 7: NOISY – breathy/rough spectra with controlled jitter.
• Bank 8: PURE/DX – clean foundational waves for stable FM/PM: SINE, COS, TRI, SQUARE, SAW, RECT, SINE+2, SINE+3.

Key behavior: The PURE/DX bank is never waveshaped by SHAPE, so it stays clean and predictable (critical for FM/PM).

Knobs

OCT – Octave offset (-4..+4). This is added to V/OCT.

FINE – Fine tuning ±1 semitone around the center.

DET – Detune depth for OSC B around its ratio (extended cents range). Use this for thickness in NORMAL mode or for shifting sidebands in PM mode.

MRPH – Morph position for OSC A (0..1). Selects among the 72 waves; the small display shows what you’re on.

MRPHB – Morph position for OSC B (0..1).

RATIO – Base frequency ratio for OSC B (relative to OSC A). Use 1.00, 2.00, 3.00, etc. for musical FM sidebands.

ENV (depth) – Depth of the ENV/IDX input, bipolar (-1..+1). Positive values make the incoming envelope increase PM index; negative values invert it (useful for “reverse expression” or dynamic bright-to-dull gestures).

BITE – Feedback amount on OSC B only (0..1). Higher values increase harmonic density and can become noisy/aggressive. In PM mode this is a big part of the classic DX edge.

SHAPE – Global waveshaping amount (0..1) applied to all non-PURE banks, on both oscillators. At 0 the module is “clean wavetable.” At higher values it becomes more saturated/folded/edgy. PURE/DX bank is always clean.

FAMT – FM amount for the FM input (bipolar). Scales the incoming FM CV. Keep small for subtle vibrato-like effects; push higher for more dramatic pitch sweeps.

PAMT – External PM amount for the PM input. This is audio-rate capable and can create through-zero-like phase effects depending on the signal you feed it.

PMOD (PM B→A) – Base modulation index for PM mode (0..1). This sets the starting brightness/metallicity before the ENV/IDX input is applied.

MIX – Only in NORMAL mode. 0 = OSC A, 1 = OSC B. Use this to blend timbres.

SPRD – Stereo width. In NORMAL mode, it widens toward “A left / B right” while preserving mono compatibility. In PM mode it adds a subtle pseudo-stereo phase skew on OSC A (small, safe).

LEVL – Output level (0..5V peak style). This scales OUT L/OUT R.

How PM Mode Works (Practical)

PM mode is where the “DX-ish” behavior lives:

• OSC A is the carrier you hear.
• OSC B is the modulator (not heard directly).
• PMOD sets the base index.
• ENV (depth) plus the ENV/IDX input adds dynamic index modulation (classic FM “brightness follows envelope”).
• BITE adds feedback on OSC B, which strongly affects sideband complexity.
• Using the PURE/DX bank for OSC A and/or OSC B gives the most stable, classic FM-like results.

Suggested Starting Patches

1) Clean two-oscillator stereo (NORMAL)

• MODE = NORMAL
• MRPH and MRPHB choose two contrasting waves
• MIX around 0.5 for blend
• SPRD around 0.5–1.0 for width
• SHAPE at 0 for clean wavetable, or raise it for bite

2) Classic DX-ish bell (PM)

• MODE = PM
• OSC A = PURE SINE (bank 8)
• OSC B = PURE SINE or SINE+2
• RATIO = 2.00 to 6.00 range (experiment)
• PMOD moderate (0.2–0.5)
• Patch an ADSR into ENV/IDX and raise ENV depth
• Add a touch of BITE for edge

3) Expressive FM pluck (PM)

• MODE = PM
• Use a fast envelope into ENV/IDX
• ENV depth positive for “bright attack then dull” behavior
• Try negative ENV depth for inverted dynamics

About the Wave Displays

The two small displays show the current wave selection for OSC A and OSC B. The display reflects the effective shaping amount (SHAPE and bank rules). PURE/DX waves stay unshaped, so they will continue to look “clean” even when SHAPE is high, which is intentional.

Reset Usage

The RESET input resets both oscillators to phase 0 on a rising edge and clears internal one-sample feedback memory. Use it to lock the phase for consistent transients, sync-like effects, or to restart FM tone generation in a predictable way.

Quick Control Map (what to tweak first)

• Pitch: V/OCT, OCT, FINE
• Wave choice: MRPH (A), MRPHB (B), plus MRPH CV
• NORMAL tone: MIX, SPRD, SHAPE
• PM tone: PMOD, ENV depth, ENV/IDX input, RATIO, BITE
• Motion: FM input + FAMT, PM input + PAMT
• Output: LEVL