Studio Violin: Building a Physically Modelled Bowed-String Instrument in Instrudio

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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

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The result is a sound engine that behaves less like a static sample trigger and more like a continuously controlled bowed instrument.

## [](#stradivaristyle-body-resonances)Stradivari-style body resonances

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

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There are also per-string offsets:  

G string: warmer, reduced bridge hill E string: brighter, boosted bridge hill

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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.

## [](#sympathetic-resonance)Sympathetic resonance

Studio Violin includes sympathetic resonance using four triangle oscillators tuned to the open strings.  

Amplitude = (1 − cents / 20) × 0.038

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The closer the played note is to an open-string relationship, the stronger the sympathetic contribution becomes.

## [](#expressive-controls)Expressive controls

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.

## [](#signal-chain)Signal chain

The current signal chain is:  

PeriodicWave oscillator → H2 oscillator → chorus oscillators → WaveShaper → injection gain → warm shelf → 8 peaking body EQ bands → master output

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## [](#singlesourceoftruth-instrument-architecture)Single-source-of-truth instrument architecture

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:

1.  The web audio synthesis engine
2.  The instrument UI
3.  External MIDI CC routing
4.  Note mapping
5.  Plugin bridge event protocol
6.  Preset management
7.  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.

## [](#runtime-metrics)Runtime metrics

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()

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## [](#why-this-matters)Why this matters

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.

## [](#repo)Repo

[https://github.com/GareBear99/Instrudio](https://github.com/GareBear99/Instrudio)

## [](#feedback-wanted)Feedback wanted

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.