01 / Write a rhythm
Press Start to hear the loaded groove. Click an instrument name to select and audition it, then use the 16 keys to place hits. Click a lit key again to remove it.
Choose Strong, Weak or Flam before entering steps. Total Accent opens a shared accent lane. Drag knobs vertically, use arrow keys, or double-click to reset.
02 / Shape the groove
STANK (0–10) delays alternate sixteenth notes. Flam adds a second strike to bass drum, snare and tom hits. Scale changes the subdivision; Last Step sets pattern length.
Tap Write records the selected voice into the nearest step as you audition. Space starts or stops; keys A S D F G H J K L ; ' audition the 11 voices.
03 / Build a track
Choose one of 96 patterns using Bank, Group and Pattern. Patterns are saved on this device; use Save Session to keep custom samples. Copy and Paste duplicate an entire pattern. The arranger chains patterns into four tracks.
Save Session downloads a backup including your uploaded samples, sound settings, patterns and tracks. Export WAV renders the selected pattern for four repetitions, with a short tail. MIDI Connect requests browser MIDI access for drum note input and note/clock output.
Taking it to a DAW? Export Stems ZIP downloads 11 separate drum tracks. Unzip and import all WAVs at bar 1 with your project tempo matching SP909. Each file covers the selected pattern repeated four times, plus tails. Current mutes are respected. Stereo 44.1 kHz / 32-bit float stems retain your sound settings, with the shared master limiter bypassed for mixing.
04 / Bring your own sound
Open Sample Bank or Load Sound on a voice. Upload one sound or a batch of up to ten; Preview auditions it and Factory restores the original. Tune changes pitch, Decay shortens the sound, and the other panel controls shape it. Save Session includes your audio; reload that backup to restore your custom kit.
05 / Add the low end
In BASSLINE 01, choose a key, scale and groove, then Generate. Density sets how busy it is; Undo brings the previous line back. Select a step to edit its note, octave or accent. Bass on enables playback with the main Start button. Shape the tone with Voice, Cutoff, Resonance and Length.
Quarter-note ducking lowers the bass on every beat so the kick has room. Amount controls the dip (zero turns it off); Recovery controls how quickly the bass returns. Bass notes belong to each pattern; tone and duck settings apply across the session. WAV exports include the bass.
Phones & tablets
Tap Start to enable sound. Swipe the sound panel and pattern grid sideways. Drag knobs vertically; use the large step keys and Strong / Weak / Flam buttons to write rhythms. After switching apps or locking the screen, tap Start again. Save Session before closing to keep custom audio. Exports open a file panel with Download and, when supported, Share / Save to Files. MIDI needs browser support and may be unavailable on your device.
About this instrument
This is an independent, evolving TR-909-inspired instrument, not a verified circuit-accurate emulator. The drums are synthesized; hats and cymbals use samples from Matthew Cieplak’s ER-99. The engine and interface have been rewritten.
Hardware-style sound controls and sequencing, with browser conveniences. Exact component behavior, DIN sync, tape storage, external MIDI clock input and the original button-combination operating system are not emulated.
Distributed under GPL-3.0. Download complete source. Roland and TR-909 are trademarks of Roland Corporation. No affiliation or endorsement.