Bantar Builder: banjo → tār/setār fret calculator web app - #1
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Browser tool to convert fretless 4/5-string banjos into Americanized tar/setar. Self-contained static app (no dependencies, no build step). Features: - Instrument parameter form (scale length, neck taper, materials, bridge/nut, string count and tuning presets mapping banjo strings to Persian roles: sefid/zard/bam/vakhan/zang). - To-scale SVG fret diagram with koron/sori neutral frets, solfege + Western + Persian-script labels, and wrap pips. - All 12 dastgah/avaz modes with skeleton-scale highlighting and optional auto-add of the frets a mode needs. - Integrated chromatic tuner (Web Audio autocorrelation) with on-neck marker and slide-to-tune adjustment hints. - Per-fret cut & wrap chart for tied Aquila Nylgut (cut length = ellipse perimeter x wraps + knot allowance), gauge suggestions, CSV export and printable shop sheet. - Generated, parameter-aware assembly order and tying directions. Math: generalized rule of 18 for fret positions; Ramanujan ellipse perimeter for tie lengths. Interval cents and modes editable in js/data.js. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01BHHNhMX5jRXoNRmTtsMnD1
New "Number of metal frets already on the banjo" input enables a hybrid build: keep the banjo's existing metal frets (exact 12-TET) and only tie Nylgut frets for the Persian neutral tones (koron/sori) that fall between them. - calc.js: existingMetalFrets param; pitches landing on a metal position are flagged 'metal' (no tie, no Nylgut) vs 'tie'. Adds metalFretList() and coincidesWithMetal(); totalNylgut() now reports tie/metal counts. - fretboard.js: draws existing metal frets as silver reference bars; in-scale metal positions get a marker instead of a tied bar. - app.js: new input wired through; fret table gains a Type column (metal ✓ / tie); summary and CSV updated; assembly guide has a dedicated hybrid procedure (metal frets as the reference grid, tie only the neutrals between them). - index.html/styles.css: input, Type column, legend swatch, tag styles. Fretless mode (0 metal frets) is unchanged. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01BHHNhMX5jRXoNRmTtsMnD1
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01BHHNhMX5jRXoNRmTtsMnD1
Units: new top-bar selector switches the whole tool between mm and inches. All length inputs and output columns convert in place; values are kept internally in mm. Nylgut gauges stay in mm (how Aquila sells them). Assembly-guide measurements and the Nylgut total follow the unit. Fret-removal plan (answers "which frets do I pull to get setar spacing on an already-fretted banjo"): classifyMetalFrets() tags each existing metal fret keep (its pitch is in the chosen Persian layout) or remove (it isn't). A new plan box lists remove/keep/add counts and fret numbers, and removed frets render as red dashed bars with an ✕ on the diagram. The octave/tonic (pitch-class do) is always kept. Documents that neutral koron/sori tones can only be added as ties, never produced by removal. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01BHHNhMX5jRXoNRmTtsMnD1
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01BHHNhMX5jRXoNRmTtsMnD1
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What this is
A self-contained browser tool for converting a fretless banjo (4- or 5-string) into an Americanized tār / setār, focused on the hardest part of that build: laying out and tying the gut frets. No dependencies, no build step — open
index.htmlorpython3 -m http.server.Features
Instrument parameters — scale length, neck taper (nut/join width and thickness, since tied frets wrap the whole neck), materials (neck/head/bridge/nut), and Nylgut knot allowance. Banjo strings map onto Persian roles (sefid / zard / bam / vākhān / zang) via tuning presets, including "Americanized" presets pitched for Western jams.
To-scale fret diagram (SVG) — every tied fret at its true distance from the nut, color-coded by type (diatonic / koron / sori / chromatic), labelled in solfège + Western + Persian script. Wrap pips on the bass edge show how many times the gut goes around the neck.
All 12 dastgāh / āvāz — Māhur, Shur, Homāyun, Segāh, Chahārgāh, Navā, Rāst-Panjgāh + the five āvāz. Selecting a mode highlights the frets it needs and can auto-add them to the fret set.
Integrated chromatic tuner — Web Audio autocorrelation pitch detection; shows Hz, nearest note, cents off, and a plain-language adjustment. A marker rides the fret diagram at the heard pitch so you can slide each tied fret to pitch.
Fret cut & wrap chart — per fret: distance, spacing, neck cross-section, wrap count, exact Nylgut cut length, and a suggested gauge from your tenor stock. Total length, CSV export, printable shop sheet.
Generated assembly guide — parameter-aware order (reference frets first), knot direction, slide-to-tune method, fill-in order, overnight re-tune.
Math
d = L·(1 − 2^(−cents/1200))(verified: octave lands at exactly L/2).Accuracy / scope
Uses a deliberate "Americanized" compromise: a 12-TET skeleton plus the principal Persian neutral tones (koron/sori) at sensible neutral-interval cents. The highlighted dastgāh scales are skeleton scales ("frets you need to play in this mode"), not a full account of the modal system. All interval cents and modes are editable in
js/data.js, and individual frets/wraps are adjustable in the UI.Testing
node --check.🤖 Generated with Claude Code
Generated by Claude Code