Studio Violin: Building a Physically Modelled Bowed-String Instrument in Instrudio I’m building Instrudio, a browser-based virtual instrument ecosystem, and the flagship instrument right now is Studio Violin. Studio Violin is a physically modelled bowed-string instrument built around Helmholtz motion synthesis, H2 harmonic correction, inharmonicity modelling, Stradivari-style body resonances, sympathetic open-string resonance, and live MIDI control. The goal is not just to make a violin-like web instrument. The goal is to prove that a single version-controlled instrument definition can drive synthesis, UI, MIDI routing, plugin bridge behavior, presets, and live update propagation from one source of truth. Studio Violin models the behavior of a bowed violin string using a synthesis chain designed around acoustic measurements and practical browser audio constraints. The instrument includes: Helmholtz bowed-string waveform synthesis H2 correction oscillator Inharmonicity chorus per string 8-band Stradivari-style body EQ Per-string tonal offsets Sympathetic open-string resonance Nonlinear bow coupling Pressure-coupled vibrato Interval-scaled portamento Bow-pressure, bow-speed, bow-point, character, brightness, attack, and vibrato controls External MIDI routing through the Instrudio app The Helmholtz waveform uses a Fourier-style bowed-string model: bₙ = −(2 / (n²π²D(1−D))) · sin(nπD) D = 0.5 + bowPressure × 0.30 The H2 correction oscillator is used to bring the second harmonic closer to the target H2/H1 balance measured in bowed-string acoustic research. Studio Violin also includes per-string inharmonicity spread: G = 0.00035 D = 0.00028 A = 0.00022 E = 0.00018 The result is a sound engine that behaves less like a static sample trigger and more like a continuously controlled bowed instrument. The body EQ model uses eight resonance bands: A0: 275 Hz A1: 475 Hz B1−: 530 Hz B1+: 580 Hz Bridge hill: 2800 Hz, Q = 6.5 Upper resonance: 4500 Hz Notch: 1100 Hz Warmth: 180 Hz There are also per-string offsets: G string: warmer, reduced bridge hill E string: brighter, boosted bridge hill This lets the instrument react differently across the G, D, A, and E strings instead of applying one flat tone curve to the whole range. Studio Violin includes sympathetic resonance using four triangle oscillators tuned to the open strings. Amplitude = (1 − cents / 20) × 0.038 The closer the played note is to an open-string relationship, the stronger the sympathetic contribution becomes. The instrument exposes controls for: Bow pressure Bow speed Bow point Vibrato rate Vibrato depth Attack Brightness Reverb Volume Playing character Character modes include: Solo Bowed Pizzicato Col Legno Tremolo Spiccato It also includes scale helpers such as G Major, D Major, A Minor, and Chromatic. The current signal chain is: PeriodicWave oscillator → H2 oscillator → chorus oscillators → WaveShaper → injection gain → warm shelf → 8 peaking body EQ bands → master output The bigger architecture behind Instrudio is the part I’m most excited about. Studio Violin is driven by a single JSON definition file. That one definition can drive: The web audio synthesis engine The instrument UI External MIDI CC routing Note mapping Plugin bridge event protocol Preset management Live auto-update propagation across connected outlets The runtime uses a remote-first fetch strategy, so definition changes pushed to GitHub can propagate to connected running instances within the cache TTL window. The default TTL is currently 5 minutes. Instrudio also includes live evaluation metrics for the single-source-of-truth runtime. The metrics panel can display: SSOT fetch latency Definition apply time Remote source availability MIDI pipeline latency These are captured with high-resolution timing through performance.now(). Metrics are also available programmatically through: InstrudioSSOTRuntime.getMetrics() InstrudioMIDI.getLatencyMetrics() A lot of virtual instruments are either sample libraries, closed plugin binaries, or isolated web toys. Instrudio is aiming for something different: web-first instruments version-controlled definitions measurable runtime behavior MIDI-aware performance bridgeable plugin architecture open development fast iteration without redeploying every outlet manually Studio Violin is the flagship proof-of-concept for that architecture. https://github.com/GareBear99/Instrudio I’m looking for feedback from: audio developers Web Audio developers musicians violinists producers plugin developers MIDI users people interested in physical modelling Useful feedback includes: browser and OS MIDI device behavior latency tone realism UI feel control response broken notes or stuck notes console errors ideas for the next instrument model Studio Violin is the flagship instrument in Instrudio, and I’m building it in public.