Skip to content
Every app

No icon yet — a stand-in

Web app

Plectrum

A browser MIDI editor for plucked strings — thirteen instruments from nine musical cultures, every note synthesized, no samples

Source onlyFree · Open source
View sourceNotify me

Screenshots

  • The piano roll showing the opening bars of the Fughetta, its three voices in purple, blue and gold
  • The Prelude in tablature on classical guitar, fret numbers on six strings with the sustained bass lines drawn between them
  • The Fughetta moved onto a koto: reachable notes as dots on thirteen strings, the rest as red crosses, and a count of notes out of reach in the status bar
  • The Prelude in the piano roll, a falling bass line in gold under blue and purple arpeggios

About Plectrum

Plectrum is a MIDI editor built around plucked-string instruments, and it has no samples and no soundfont: every note is a string simulated from scratch with an extended Karplus-Strong model, then run through a body-resonance filter chain built for that instrument. The roster covers thirteen instruments — classical and steel-string guitar, oud, bağlama, sitar, pipa, guzheng, koto, shamisen, kora, charango, banjo and harpsichord — each with its own string count, tuning and fret model. The same score shows as tablature or as a piano roll. Pitch is what the score stores, so switching instruments re-fingers a piece rather than transposing it, and any note the new instrument cannot reach is drawn as a red ✕ and counted instead of being dropped. It exports Standard MIDI and saves to JSON, and ships with an original two-movement Suite in E minor written in the editor.

Who it's for

Guitarists and string players who write in tab, and anyone curious how a piece sounds moved to a koto, sitar or kora.

What it does

  • Thirteen instruments, each with its own tuning, string count and fret model
  • Every note synthesized as a string — no samples, no soundfont
  • Tablature and piano roll over one score; Tab switches between them
  • Notes an instrument can't reach are marked with a red ✕, never dropped
  • Transport scheduled on the audio clock with a 250 ms lookahead, plus loop and metronome
  • Standard MIDI export, JSON save and load, 120 levels of undo

Behind the build

The sitar's jawari and the shamisen's sawari are a tanh inside the string's feedback loop, and the first version normalised it by tanh(drive) instead of drive.

That gave the loop a small-signal gain of about 1.5 — and a feedback loop with gain above one is not a string, it is an oscillator, so four instruments rang forever. Fingering turned out to be a scheduling problem rather than a lookup: the editor walks the score in time order, tracks which strings are still sounding, and picks each position by cost, which is why the tablature reads like something a person would play.

Information

Runs on
Web app
Status
Source only
Price
Free · Open source
Requires
A modern browser
Source
Public on GitHub
Built with
Vanilla JS & Web Audio
Stack
Vanilla JavaScriptES modulesWeb Audio APICanvas

Plectrum is source only, for now.

The code is public, but there's no packaged release yet. Build it from the repository today, or leave an email and hear when there's one you can double-click.

Tell me when it shipsView source

More web apps

See all 9

  • ArtificialWatch

    Web app

    Know the minute a new AI model drops — every provider API swept every 60 seconds

    Live

  • BEAROUT

    Web · iOS · Game

    An arcade-idle bear ranch: hunt, stack the haul, run it to the sell table, upgrade, repeat

    Live

  • FableWatch

    Web app

    Watched one AI model around the clock and called it the moment it came back — then it did

    Live

  • Lore

    Web app · macOS

    The wiki for all your agents: point it at the markdown folder they write to, and it tells you what changed and what…

    Live

  • streamcount

    Web app

    One number for your live audience — viewers summed across YouTube, Twitch, and Kick

    Live

  • Tide

    Web app

    A to-do app that takes the power features seriously — natural language, recurrence, focus, review

    Live

  • Evergreen

    Web app

    Birthday and relationship reminders — the people you love, never forgotten

    In the lab

  • Grimoire

    Web app

    A local-only studio for a personal wiki — edit, graph, curate, and capture into it

    In the lab