The 303 MIDI sequencer that drives your hardware

Stepsicle is a 303 MIDI sequencer that sends true slide, accent, and tie to your Behringer TD-3, an original TB-303, or any synth that reads MIDI. It does not make the sound. It plays the box you already own.

Why a piano roll can’t do acid

Try to program an acid line in your DAW’s piano roll and it falls apart fast. Slides turn into guesswork, accents are just louder notes, and ties leave gaps. The sound of a 303 lives in how its notes connect, and a grid of rectangles cannot express that. Stepsicle puts slide, accent, and tie on every step as real controls, so the line moves the way an acid line should.

What a 303 MIDI sequencer has to get right

Most plugins fake a slide with a portamento CC message and hope the synth cooperates. A real 303 slides when one note overlaps the next, so the pitch glides and the filter follows. Stepsicle does it the hardware way:

• Slide plays two overlapping MIDI notes, not a CC, so a TD-3 or TB-303 triggers its slide circuit exactly as designed.
• Accent fires at velocity 110, the value that opens the accent circuit on the hardware. Other steps stay below the threshold, so nothing fakes an accent by mistake.
• Tie holds the previous note instead of retriggering it, which gives you true legato rather than a long gate.

Get those three right and the part reads as a real 303 line to whatever you point it at.

It controls your synth instead of being one

Arturia Acid V, AudioRealism ABL3, and D16 Phoscyon 2 all are the synth. You get their filter and their character, and you are stuck with it. Stepsicle takes the other job. It is the brain, and your gear is the voice: a TD-3 on the desk, a real TB-303, ABL3 or TAL-BassLine on a MIDI channel, or a modular rack through the CV version. One pattern, any destination.

How a 303 MIDI sequencer compares to synth plugins

Those tools are synthesizers. Stepsicle is what tells them what to play.

Sixteen steps, twelve controls each

Every step carries note, velocity, gate length, slide, accent, rest, skip, tie, octave, nudge, note delay, and trigger probability. Editing is physical: drag a pad up for velocity, drag right for gate length, and push the gate past 100 percent to overlap the next step into a slide. Set step 5 to fire early with a 40 percent chance of playing while step 6 holds a tied note, and the line breathes instead of marching.

Patterns, chains, and scales

Build up to 128 patterns and chain them into a full arrangement. Each pattern keeps its own length, transpose of up to 36 semitones either way, rate division, and playback mode: forward, reverse, pendulum, or random. With 30 rate divisions covering straight, triplet, and dotted values from 1/32 to 16 bars, you can run a 1/16 pattern into a 1/8 reverse pattern into a 1/32 random one and let the rate follow at each boundary. A 17-mode scale filter keeps every note in key, with a per-step bypass when you want a chromatic passing tone.

Four ways to play it live

• Off runs the sequence on its own.
• Transpose shifts the whole pattern in real time from a MIDI keyboard.
• Note held = play runs the sequence only while you hold a key.
• Pattern select maps incoming notes to patterns so you can switch on the fly.

A Transport Gate overlay learns any note, so you drop in and out by holding it. Live Record captures notes and velocity straight from your keyboard. Every edit lands in a 1000-step undo history that saves with the project.

Drag patterns out as MIDI

When a line is right, drag it from Stepsicle into your DAW timeline as a Standard MIDI File at 480 PPQ. Shift-drag exports the whole chain at once. Swing from 0 to 100 percent, per-step nudge, and per-step note delay are baked into the exported notes, so the part arrives already grooved.

Questions

Pricing

Part of Stepsicle. Also available as an envelope shaper and a CV sequencer. One license includes all three, and every variant shares the same pattern format.