Murmur Signal Architecture

Signal path

INPUT

MIDI note-on / prompt-generated parameters

↓

ENGINE LAYER

8 operator engines, run in parallel

• Classic
• Wavetable
• FM/PM
• Additive
• PhaseShape
• Granular
• NoiseChaos
• Resonator

↓

FILTER

↓

MODULATION

↓

FX

↓

OUTPUT

Source: murmur-app (C++20 DSP core). See murmur-app on GitHub for the implementation.

ENGINE COUNT

murmur-app’s own README (the source of truth for the DSP core) lists 8 operator engines as implemented. Murmur’s marketing content lists a 9th (“External-In,” a live sidechain-input engine) as part of the product vision — it isn’t confirmed shipped in the DSP core as of this audit. See docs/engineering/design-source.md for the full discrepancy note.

Filter stage

The filter stage is a resonant lowpass. The curve below is a real computed response (not a screenshot) — it updates from the cutoff/resonance props whenever this page is rebuilt, which is the point: Atlas can render correct DSP curves from data instead of maintaining static diagrams by hand.

201001k10k20k

LOWPASS · CUTOFF 1,200 Hz · Q 0.71

201001k10k20k

LOWPASS · CUTOFF 1,200 Hz · Q 4.50

The second curve shows the same cutoff at higher resonance (Q 4.5) — note the peak forming just below the cutoff frequency, which is what lets a resonant sweep “sing” as it moves.

Related

• Synth Parameter Reference for exact filter parameter ranges and defaults
• A full D2 topology diagram of this signal path lives at diagrams/source/murmur-signal-chain.d2 in the murmur-docs repo — render it with npm run diagrams