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sellmyvibe
For saleWorking prototype

VelvetCircuit: Polyphonic synth and sequencer

AI generated A playable browser synth with eight voices, four sounds, a step sequencer and WAV rendering.

Screenshots

  • VelvetCircuit synthesizer with oscillator controls, envelope, sixteen note steps and playable keyboard

Screenshots supplied by the seller.

Open demo (opens in a new tab)

Description

AI generated by Codex for Shai. An original browser synthesizer with eight voice polyphony, two blendable oscillators per note, detune, lowpass filter, resonance, ADSR envelope and feedback echo. Includes four original sound presets, a 25 key keyboard, computer keyboard input, editable 16 step note sequencer with rests, and stereo 44.1 kHz PCM WAV rendering with peak and RMS reporting. Patch and sequence JSON backups are supported. This is a browser instrument, not a VST, Audio Unit or DAW plugin.

The hosted demo works in memory only because its sandbox disables storage. Export a JSON backup to retain edits across reloads. The delivered source supports local browser persistence on a regular static host.

Buyer receives editable source, core tests, documentation, and deployment setup. Private source handover is arranged by the seller; no hosting account or ongoing support is included.

Condition

Development stage: Working prototype (seller-declared)

Seller-declared: provided by the seller, not independently verified by SellMyVibe.

  • Solo creator
  • Mainly AI-generated
  • Under one month in development
  • Tests included
  • Setup guide included
  • Demo available

What works

  • Playable 25 key instrument with up to eight synth voices
  • Four presets, oscillator blend, detune, filter, ADSR and echo
  • 16 editable sixteenth note steps with 60 to 180 BPM transport
  • Stereo WAV sequence rendering with signal level report and JSON project backup
  • JSON backup/import; hosted demo works in memory without network requests

What’s unfinished

  • Browser instrument only; no native plugin or DAW integration
  • No MIDI input, microphone recording, sample import or automation lanes
  • WAV export renders the sequence rather than recording keyboard performance
  • Embedded browsers may block WAV download; standalone source supports normal downloads
  • Audible device playback and broad device compatibility require buyer verification

Included assets

Full source code

Documentation

Deployment setup

Test suite

Technologies

HTML5, CSS3, Vanilla JavaScript ES modules, Browser localStorage (standalone source only)

Setup requirements

Unzip source and run python3 -m http.server 8080 in the folder. Open http://localhost:8080 or deploy to a static HTTPS host. No build or API key. Node 20+ runs test.mjs. See README.md and QA.md.

Dependencies and ongoing costs

No external libraries, APIs, backend, external fonts, images, or paid subscriptions. Hosted demo is served by SellMyVibe. Standalone source requires a static HTTP/HTTPS host, which may be free within provider limits; paid plans, overages, and custom domains may cost extra.

Known limitations

Working prototype. Browser instrument only; no native plugin or DAW integration. No MIDI input, microphone recording, sample import or automation lanes. WAV export renders the sequence rather than recording keyboard performance. Embedded browsers may block WAV download; standalone source supports normal downloads. Audible device playback and broad device compatibility require buyer verification. App data resets on reload in the hosted demo; export JSON backups. See the app description for standalone storage behavior. No independent security audit or broad device/browser certification.

Listings are reviewed for completeness and clarity before publication. Approval is not a guarantee of quality, ownership, security or commercial success. Read the details and ask questions before buying.