TBD03

A TB-303-style acid bass voice — Braids macro-oscillator driven through a choice of analog-modelled diode-ladder filters, with a dedicated filter envelope and 303-style accent.

Available on: Tracks 9 and 10 Built on: Mutable Instruments Braids MacroOscillator + CTAG diode-ladder filter models.

Character

Braids provides the tonal source — saw, square, FM, and many other Braids synthesis models via the Shape knob. A filter-envelope drives the cutoff for the squelchy 303 character. Accent sharpens short decays and lifts gain per step. Four filter variants range from classic ZDF to Karlson to Blaukraut for different flavours of acid grit.

Gotchas before you tweak:

  • Slide is not yet wired in the firmware — setting per-step slide currently has no audible effect. Tracked as a follow-up DSP task. Use pitch glides via tied steps as a workaround.
  • Accent is a per-track toggle controlled by the Accent knob (and P-lockable per step). Any knob value above 0 turns accent ON. For alternating-step 303 accent patterns, parameter-lock the Accent knob on the steps you want accented.
  • Tim EG, Col EG, Acc Lev are conditional knobs — they only produce audible change when their dependencies are in place. See Conditional modulation knobs below.

Macros

Three macros ship for this machine — different layouts of the same DSP voice, pick the one that matches how you want to perform:

  • td3-allparams — full 15-knob deep access across 4 pages (Osc / Filter / Mod / Env). For sound design and per-parameter automation. Shipped preset: F Default.
  • td3-hybrid — semantic 3-page layout (Osc / Filter / Perf) that re-arranges the same parameters into more intuitive groupings, with a “performance” page collecting the live-tweak knobs. Shipped presets: H Bass, H Squelch.
  • td3-acidbass — 4-knob performance macro: Squelch / Grit / Envelope / Accent. Each knob fans out to multiple underlying DSP ctrls so one twist changes a whole aspect of the sound at once. Hi-res NRPN sources for smooth sweeps. Shipped presets: P Classic, P Dirty.

The preset picker name prefix tells you which macro is behind a preset:

  • F — Full all-params macro (15 knobs across 4 pages).
  • H — Hybrid layout (3 pages with Perf grouping).
  • P — Performance macro (4 fan-out knobs).

td3-allparams — page layout (4/4/4/3)

The deep-access macro. Every shipped TBD03 sound exposing the full parameter surface uses this layout.

Page Knob 1 Knob 2 Knob 3 Knob 4
Osc Shape Timbre Color Warp
Filter Cutoff Reso Type Drive
Mod Env Amt Tim EG Col EG Acc Lev
Env VCA Dec VCF Dec Accent —

Osc

td3-allparams — Osc page

Parameter What it does
Shape Braids synthesis model (47 shapes, same catalogue as Mono Synth). SAW\|SQR (shape 2) is the classic acid starting point.
Timbre Braids parameter 0 (model-specific). Hi-res 14-bit. See note on base-level headroom below if using Tim EG.
Color Braids parameter 1 (model-specific). Hi-res 14-bit. See note on base-level headroom below if using Col EG.
Warp Signature waveshaper amount — adds analog-style fold/grit at the oscillator stage. Hi-res 14-bit.

Filter

td3-allparams — Filter page

Parameter What it does
Cutoff Filter cutoff frequency. Hi-res 14-bit with log curve for smooth sweeps.
Reso Filter resonance — crank for squelch. Hi-res.
Type Filter topology: 0 ZDF-Boost (aggressive), 1 Karlson (warm), 2 Blaukraut (vintage), 3 Pirkle ZDF (clean). Four modes 0–3. (A fifth internal mode exists in the DSP but is unreachable via macro — ignore until a firmware fix lands.)
Drive Filter input drive / soft-clip gain 1×–30×. Hi-res.

Mod

td3-allparams — Mod page

Parameter What it does
Env Amt Filter-envelope amount — how much the VCF envelope opens the cutoff. Classic 303 squelch lives here. Hi-res.
Tim EG VCF envelope → Timbre modulation amount. Hi-res. Conditional — see below.
Col EG VCF envelope → Color modulation amount. Hi-res. Conditional — see below.
Acc Lev Accent level — extra cutoff boost when Accent is ON. Hi-res. Conditional — see below.

Env

td3-allparams — Env page

Parameter What it does
VCA Dec Amplitude envelope decay, 0–5 s exponential. Hi-res.
VCF Dec Filter envelope decay, 0–5 s exponential (Accent shortens this to 0.5 s for per-step sharpness). Hi-res.
Accent OFF/ON — per-track accent toggle. Shortens VCF Dec and boosts VCA gain + cutoff when ON. Lock per-step for 303-style accent patterns.

td3-hybrid — page layout (4/4/4)

A semantic re-grouping of the same DSP into 3 pages. Same parameters, different organisation: Osc brings shape + the two timing knobs (Length / Sweep) into one page, Filter keeps Cutoff/Reso/Env/Type together, and Perf collects the four “live tweak” controls (Warp / Drive / Motion / Accent) on a single page for fast performance edits.

Page Knob 1 Knob 2 Knob 3 Knob 4
Osc Shape Timbre Length Sweep
Filter Cutoff Reso Env Type
Perf Warp Drive Motion Accent

Osc

td3-hybrid — Osc page

Parameter What it does
Shape Braids synthesis model (same 47-shape catalogue). SAW\|SUB (shape 6) is the classic acid bass starting point on this macro.
Timbre Braids parameter 0 (model-specific). Hi-res 14-bit.
Length VCA decay alias — controls how long each note sustains. Hi-res, exponential. Same DSP target as VCA Dec on the all-params macro.
Sweep VCF decay alias — controls how long the filter envelope sweeps before settling. Hi-res, exponential. Same DSP target as VCF Dec.

Filter

td3-hybrid — Filter page

Parameter What it does
Cutoff Filter cutoff frequency, log-swept 14-bit.
Reso Filter resonance, 14-bit.
Env Filter envelope amount. Same DSP target as Env Amt on the all-params macro.
Type Filter topology select (0..3, same four modes as on the all-params macro).

Perf

td3-hybrid — Perf page

The performance / character page. Pick the four live-tweak knobs you’ll P-lock per step or twist during a take.

Parameter What it does
Warp Oscillator waveshaper amount. Hi-res.
Drive Filter input drive / soft-clip gain. Hi-res.
Motion Combined Tim EG + Col EG modulator routing — one knob to add timbre/color movement under the filter envelope. Hi-res. Replaces the two separate Tim EG / Col EG knobs from the all-params macro.
Accent OFF/ON accent toggle. P-lock per step.

Conditional modulation knobs

Three knobs on the Mod page are not broken if they seem quiet — they require other parameters to be in the right position to produce audible change.

Tim EG and Col EG

Both modulate the oscillator’s timbre/color by the VCF envelope. Two conditions have to be met to hear them:

  1. VCF Dec must be > 0. The modulation source is the filter envelope. With VCF Dec at zero there is no envelope to modulate from — Tim EG and Col EG appear dead regardless of their value.
  2. Base Timbre / Color needs headroom. The modulation is additive only — it always adds on top of the base Timbre (or Color) setting, and the result clamps to the hardware max. If base Timbre is already high (say 70 %+ of the knob), the mod hits the ceiling immediately and the audible sweep is tiny. Lower the base and the same Tim EG value becomes dramatic.

A good starting combination for clearly-audible Tim EG / Col EG:

  • VCF Dec around 20–30 % (≈ 0.5–1 s envelope).
  • Base Timbre / Color at 15–25 %.
  • Tim EG / Col EG at 50–80 % to hear the modulation sweep.

Acc Lev

Gated on Accent. When Accent = OFF (the factory default for F Default), Acc Lev does nothing regardless of its value. Turn Accent = ON first, then dial Acc Lev to hear the extra filter-envelope punch on note-on. In live play, P-lock Accent = ON on the steps you want accented and leave Acc Lev at a fixed level on the sound knob.

Accent: binary toggle vs continuous intensity — why the macros differ

Confusing at first glance: the deep-edit macros show Accent as a binary OFF / ON, but the performance macro shows Accent as a continuous 0–100 % knob. Both are correct — they expose two different aspects of the same DSP behaviour.

The TBD03 DSP has two separate accent-related atomics, both writable from macros:

DSP atomic Type What it controls
accent (ctrl 19) Binary in practice — used as a boolean if (td3_isAccent) { … } in RackTBD03::Process. Any non-zero value = accent ON. When ON at note-trigger: shortens VCF Decay to a fixed short value (kAccentDecay) and multiplies VCA gain by kAccentVCAFactor. The classic 303 “extra punch” on accented notes.
accent_level (ctrl 23) Continuous 0..1 (hi-res 14-bit). How much extra cutoff modulation depth the accent adds. Higher = sharper, more dramatic accent sweep.

In other words: accent is the trigger flag (“is this note accented?”), accent_level is the intensity dial (“how strong is the accent boost when it fires?”).

Deep-edit macros (td3-allparams, td3-hybrid): expose them as two separate knobs.

  • Accent knob (max: 1, ui: onoff) → just the binary trigger flag. P-lock per step for 303-style accent patterns.
  • Acc Lev knob (max: 16383, hi-res NRPN) → just the intensity. Set once for the song, then leave alone.

Performance macro (td3-acidbass): collapses both into a single hi-res knob.

  • Accent knob (max: 16383, hi-res NRPN, fans out to BOTH ctrl 19 + ctrl 23):
    • Wire 0 → both atomics = 0 → accent OFF, no boost.
    • Wire > 0 → ctrl 19 receives the value (becomes truthy → accent ON) AND ctrl 23 receives a proportional value (sets the boost intensity).
    • Net effect: rotating one knob smoothly takes you from “no accent at all” through “subtle accent” up to “full slammed 303 accent” without needing a separate flag-flip. Trade-off: you lose the ability to lock the trigger flag off without also zeroing the intensity (rare in practice — if you wanted no accent, you’d just leave the knob at 0).
Macro Accent knob behaviour Acc Lev exposed?
td3-allparams Binary OFF / ON Yes — separate Acc Lev knob on Mod page
td3-hybrid Binary OFF / ON No — Acc Lev not on the page; defaults from the preset apply
td3-acidbass Continuous 0–100 % (fan-out) Implicit — driven by the same Accent knob

Practical guidance:

  • If you want classic 303 accent-on-some-steps patterns → use td3-allparams or td3-hybrid, P-lock the Accent toggle to ON on the steps you want accented, and dial Acc Lev on the song-level sound page.
  • If you want a single live-performance knob that smoothly takes you from “clean” to “fully accented” → use td3-acidbass. Twist the Accent knob during a take or P-lock it across steps for a continuous accent ramp.

Dialing a classic acid bass:

  1. Set Shape to SAW\|SQR (2).
  2. Cutoff around 30–60 %, Reso at 80 %+.
  3. VCF Dec short (10–25 %), VCA Dec short-to-medium.
  4. Env Amt high (60 %+) for the squelch sweep.
  5. Lock Accent ON on alternating steps for 303-style groove.

td3-acidbass — performance macro (1 page)

td3-acidbass — Perform page

Single-page 4-knob macro that collapses the 15-knob deep layout down to four “fan-out” controls. Each source knob is hi-res 14-bit NRPN and drives multiple underlying DSP ctrls in parallel — so one twist changes a whole sonic dimension. Good for quick live tweaking and parameter-locked acid lines.

Knob Fans out to
Squelch Cutoff (log sweep across full range) + Reso (3000 → 13000) + Env Amt (5000 → 15000). The primary 303-character knob — turns the entire filter sweep up together.
Grit Warp (full range) + Drive (0 → 12000). Adds oscillator-side shaping + filter overdrive together.
Envelope VCA Dec + VCF Dec — longer envelopes for sustained parts, shorter for staccato.
Accent Accent toggle (0 = OFF, any value > 0 = ON) + Acc Lev intensity (0 → 12000). At 0, clean sound with full VCF Dec; above 0, accent kicks in proportionally.

The non-modulated params (Shape, Timbre, Color, filter Type) are held at fixed defaults inside the macro (SAW|SQR, moderate Timbre, ZDF-Boost filter). Use td3-allparams or td3-hybrid if you need to vary those.

Factory presets

Preset Macro Character
F Default td3-allparams Neutral starting point across the full 15-knob surface. Timbre / Color kept modest so Tim EG / Col EG have audible headroom. The deep-edit baseline.
H Bass td3-hybrid Punchy SAW + SUB layered acid bass on the 3-page layout. Tight Length/Sweep, mid Cutoff with strong Env, ZDF filter. The “go-to” preset for most acid-bass parts.
H Squelch td3-hybrid Brighter squelchier variant on the same hybrid macro — higher Cutoff, more Reso, more Sweep. Compare against H Bass and pick whichever fits the track.
P Classic td3-acidbass Performance preset — moderate Squelch (~67 %), light Grit, mid Envelope, mid Accent. Classic 303 vibe through the 4-knob fan-out macro. Twist live.
P Dirty td3-acidbass Performance preset — high Squelch (~85 %), heavy Grit, short Envelope, strong Accent. Aggressive distorted acid for darker tracks.

The preset picker name prefix tells you which macro is loaded: F = full 4-page deep-edit, H = hybrid 3-page, P = performance 1-page (4-knob fan-out). You can also author your own preset via the WebUI Preset Manager and save it against any of the three macros.

See also

  • Mono Synth — same Braids oscillator without the 303-style filter path.
  • Parameter Locks — essential for acid programming (lock Accent per-step, automate Cutoff / Env Amt sweeps).

Origin & credits

CTAG’s TBD03 engine. Combines Mutable Instruments Braids MacroOscillator (Émilie Gillet, MIT-licensed) with CTAG’s own analog diode-ladder filter models and a 303-style envelope + accent engine by Robert Manzke (GPL 3.0).

  • DSP sources: braids/macro_oscillator.h, filters/ctagDiodeLadderFilter*.hpp
  • TBD-16 wrapper: rack/RackTBD03.hpp / .cpp
  • Related reading: Mutable Instruments Braids manual