Nodes
Spectral nodes
Nodes for spectral composition — working with harmonic series, frequency-to-pitch conversion, microtonal quantization, spectral morphing, and formant-based filtering. The reconciliation nodes bridge spectral analysis and modal tuning, following Rami Chahin's spectral-microtonal method for maqam and Moroccan tab' scales.
| Node | Inputs | Outputs | Description |
|---|---|---|---|
| Harmonic Series | number fundamental (Hz, default: 131) number num-partials (default: 16) |
list frequencies (Hz) | Generates N partials of the harmonic series from a given fundamental frequency. Partial N has frequency = fundamental × N. The output is a list of frequencies in Hz, which can be converted to midicents with the Freq to MC node. |
| Freq to MC | list frequencies (Hz) | midicents | Converts a list of frequencies in Hz to midicents using the formula: mc = 100 × (69 + 12 × log2(freq / 440)). This bridges the frequency domain (spectral analysis, harmonic series) and the pitch domain (notation, transposition). |
| Interval Vector | midicents pitches | list intervals (midicents) | Computes all intervals between adjacent pitches in a list. The output has one fewer element than the input. Useful for analyzing the intervallic content of a melody or pitch sequence and for feeding into transformation nodes. |
| Microtonal Quantize | midicents pitches number divisions (default: 24) |
midicents | Snaps each pitch to the nearest step in an equal division of the octave. Divisions = 12 gives standard semitones; 24 gives quarter-tones; 48 gives eighth-tones; 72 gives twelfth-tones. Any integer division is supported for exploring non-standard equal temperaments. |
| Scale Quantize | midicents pitches list scale-degrees (midicents offsets) |
midicents | Snaps pitches to the nearest degree of a custom tuning system. The scale is defined as a list of midicents offsets within the octave (e.g., a just-intonation major scale). Pitches are quantized to the nearest scale degree across all octaves. |
| Spectral Round | midicents pitches number fundamental (Hz, default: 131) |
midicents | Rounds each pitch to the nearest harmonic partial of the given fundamental. The result is a set of pitches that all belong to the same harmonic series, creating spectral coherence from arbitrary pitch material. |
| Spectral Morph | midicents field-A midicents field-B number morph (0.0–1.0, default: 0.5) |
midicents | Interpolates between two harmonic fields. At morph = 0.0 the output is identical to Field A; at 1.0 it is Field B; intermediate values produce pitch sets that smoothly transition between the two spectral worlds. A core technique in the spectral composition tradition, enabling continuous harmonic transformation. |
| Harmonic Distance | midicents pitches number fundamental (Hz, default: 131) |
list distances | Measures the consonance or roughness of each pitch relative to a fundamental by computing its distance from the nearest harmonic partial. Low values indicate near-harmonic (consonant) pitches; high values indicate inharmonic (rough) pitches. Use this to analyze or sort pitch material by spectral tension. |
| Formant Filter | midicents pitches list formants (Hz centers, default: [800, 1200, 2500]) number bandwidth (Hz, default: 200) |
midicents | Filters a pitch collection through vocal formant regions. Only pitches whose frequencies fall within the bandwidth of one of the specified formant center frequencies are retained. Inspired by spectral techniques for filtering harmonic fields through the resonance characteristics of vowel sounds, creating timbral associations between instrumental pitch and vocal quality. |
| Field to Scale | midicents pitches list amplitudes number tolerance (cents, default: 35) number max-degrees |
list scale (cents) list weights |
Derives a reusable tuning from analysed partials — the analyze-to-tuning half of the spectral-microtonal loop. Folds a Spectral Analyze pitch field into a clean set of cents degrees, clustering by pitch class and ranking by energy. Measure a mode's intonation off a recording (a Moroccan oud, a bowed cymbal) instead of guessing it. |
| Spectral Reconcile | list scale (cents) number fundamental (Hz) number pull (0.0–1.0, default: 0.5) number tolerance (cents, default: 60) |
list scale (cents) list deviations (cents) |
Bends each degree of a maqam or tab' toward the nearest strong partial of a reference spectrum — the bridge at the heart of Rami Chahin's spectral-microtonal method. The result is a tuning at once modal in contour and spectral in intonation; the deviations output reports how far each degree moved. |
| Drone Consonance | list scale (cents) number drone (Hz, default: 261.6) number drone-partials (default: 8) number tone-partials (default: 6) |
list consonance (0–1) list roughness |
Scores each scale degree's sensory consonance against a sustained drone using the Plomp–Levelt / Sethares roughness model. Maqam and tab' practice unfolds over a drone, so this reveals which degrees fuse and which beat — a read-only analytic probe. |
Studies that use these nodes
Clocks and Clouds — metronomes, Continuum, the natural horn
Clocks and Clouds: four metronomes dividing one bar into 4, 5, 6 and 7, Continuum's three-against-two…
Turangalîla — rhythmic characters, the chord of resonance, colour
Turangalîla: rhythmic characters that grow, shrink and stay, the chord of resonance from the harmonic…
Saariaho — Spectral Morph
A spectral study after Saariaho: the harmonic series of C, a Spectral Morph to F one step per bar, a Formant…
Bodapolska med sekundstämma
A Dalarna polska with folk intonation (blå toner) and a second-fiddle sekundstämma.
Naturton — sälgflöjt över bordun
The willow-flute overtone scale (naturton) — a melody on the natural harmonics over a drone.
Flight of the Bumblebee — a chromatic engine
Flight of the Bumblebee as a machine: a falling chromatic wave interleaved with its upper neighbour…
The Black Page — statistical density
The Black Page: nested tuplets bar by bar, five against seven, a density envelope thickening the tuplets…
Inca Roads — the Lydian vamp, 19/16, and the angular line
Inca Roads: a two-chord Lydian vamp from typed chord symbols with its scale derived, a whole tune in 19/16…
G-Spot Tornado — Synclavier stochastics
G-Spot Tornado: Euclidean drums, weighted-choice and Markov lines, the logistic map driving pitch and…
Wire these nodes into a piece of your own.
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