P33

Objectives

By the end of this chapter you will be able to:

  • Distinguish melodic slots (1–8) from drum slots (9–16).
  • Place a sound on a specific step of the 16-step sequencer.
  • Press play and hear your sound loop.
  • Edit a step (remove it, move it, change its slot).

Musical concept: what is a step?

A step sequencer is a row of buttons, one per beat, that plays a sound when you press play and reaches that step. The PO-33 has 16 steps in a 4×4 grid. Step 1 is the top-left button. Step 16 is the bottom-right button.

Each step is a sixteenth-note in 4/4 time. That means there are four steps per beat. In one bar (4 beats) there are 16 steps. In a 4-minute song at 120 BPM there are 1,920 steps. The PO-33 loops one bar (16 steps) by default. You can chain patterns to make longer songs — we’ll get to that in Chapter 15.

Sidebar — Hewitt’s note values. Michael Hewitt (Music Theory for Computer Musicians) introduces note values as fractions of a whole note: a whole note is four beats, a half note is two beats, a quarter note is one beat, an eighth note is half a beat, a sixteenth note is a quarter of a beat. The PO-33’s “step” is exactly a sixteenth note: each step is one quarter of one beat, and four steps make one beat.

When you press a step button while the sequencer is playing, you toggle that step. If the step is empty, it becomes occupied (you’ve just written a note there). If the step is occupied, it becomes empty (you’ve erased it). This is how you “write” a beat into the PO-33.

Slots vs. steps

There are two distinct things to keep straight:

  • A slot is a place to store a sound. Slots are numbered 1 to 16. Slot 1 can hold a kick drum. Slot 2 can hold a snare. Slot 15 can hold a hi-hat. Slots are persistent — turn off the device, they remain.
  • A step is a place to trigger a sound. Steps are also numbered 1 to 16, and they loop. Step 5 might play slot 2 on every loop, then step 13 might also play slot 2, then step 14 might play slot 15.

Slots are the cast of characters. Steps are the choreography. The same kick drum (slot 2) might play on step 1, 5, 9, and 13 (a four-on-the-floor pattern), or it might play only on step 1 and step 11 (a syncopated pattern). The slot doesn’t change; the steps it plays on do.

Melodic slots vs. drum slots

The PO-33 splits its 16 slots into two groups:

  • Melodic slots (slots 1–8): when you play these from the sequencer, the device chooses a pitch for you based on which step is playing. Pad 1 plays C4 (middle C), pad 2 plays C#4, pad 3 plays D4, …, pad 8 plays G#4, pad 16 plays D#5 (the 16th pad triggers D#5 because the chromatic scale is one octave wide — 16 semitones — and pad 1 is C4). This is the auto-mapping feature (called F-005 in the Ravine: Phoenix firmware). It means that, by default, pressing different steps plays different notes — pad 1 is C, pad 8 is G#, pad 16 is D#.
  • Drum slots (slots 9–16): when you play these from the sequencer, the device plays a slice of the recording. Pad 1 plays the first 1/16th of the active drum slot’s recording. Pad 16 plays the last 1/16th. All 16 pads trigger 16 equal slices, so the entire recording is reachable — pads 1–16 cover slices 1–16. This is the auto-slicing feature (F-024). If you record a 4-second break into slot 9, pressing pad 1 plays the first 0.25 seconds, pressing pad 2 plays the next 0.25 seconds, …, pressing pad 16 plays the last 0.25 seconds.

The two halves are intentionally different. Melodic slots let you play melodies and chords. Drum slots let you play sliced breaks.

Sidebar — the ranges are swapped on Ravine: Phoenix (ADR-0002). On the real PO-33 — and in the rest of this book — slots 1–8 are melodic and 9–16 are drum. The Ravine: Phoenix firmware deliberately reverses this: slots 1–8 are drum and 9–16 are melodic, so the device leads with drum beats. Everything else about the slots behaves the same. When you move between this book and a Ravine: Phoenix device, swap the numbers.

Sidebar — PO-33 vs. Ravine: Phoenix. The original PO-33 maps the 16 melodic pads to one octave of the chromatic scale. The Ravine: Phoenix firmware does the same. Drum auto-slicing was ❌ missing in our v1 firmware before October 2025; this book is written assuming auto-slicing works (v1.1 firmware and later). On a real PO-33, drum auto-slicing has always worked.

PO-33 Playback: writing your first beat

To write a single sound into the sequencer, you use write mode. The flow mirrors the PO-33 manual’s fill pattern step:

  1. (Optional) Select a pattern other than 1: hold PATTERN + a pad.
  2. Press WRITE to enter write mode. The screen shows a WRITE label.
  3. Select the sound you want to place: hold SOUND and press its pad (for example SOUND + pad 1 selects slot 1). Release SOUND. This is the manual’s “press the number of the sound to add”.
  4. Now each pad press toggles that step for the selected sound. Press pad 1 to place the sound on step 1; press it again to remove it. Press pad 5 to place it on step 5, and so on.
  5. Press WRITE again to exit write mode.

Two things to keep straight, because the same 16 pads do double duty:

  • A pad means different things with and without SOUND held. With SOUND held, a pad selects a sound. With no modifier (and write mode on), a pad toggles a step.
  • The sound written is the selected sound, not “the pad you pressed”. In step 4, pad 5 writes the selected sound to step 5 — it does not write “slot 5”.

For your first beat: press WRITE, select the kick with SOUND + pad 1, then press pad 1, pad 5, pad 9, and pad 13 to place that sound on those four steps. The pads are the steps here — 1, 5, 9, 13 are the four beats of the bar. Press WRITE to exit, then press PLAY to hear the four-on-the-floor kick. We’ll build on it in Chapter 4.

How the write-mode exercises in this book are written. In write mode the 16 pads are steps, and the sound being placed is whatever you most recently selected with SOUND + pad. So an exercise line like

Step 5: kick (slot 9).

expands to: hold SOUND, press pad 9 (select slot 9), release SOUND, then press pad 5 (toggle step 5). The name in parentheses is the sound; the step number is the pad you actually press. This is why the same pad can mean “a sound” (while SOUND is held) or “a step” (with no modifier).

Some exercises are written with a sound’s pad number as shorthand, e.g. “step 1: pad 9 (kick)”. Read the number in parentheses as the sound (the kick, which lives in slot 9) and the step as the pad you press — so “step 1: pad 9 (kick)” means: select the kick (SOUND + pad 9), then press pad 1.

The sequencer screen

The PO-33’s screen shows a playhead (the current step) and a pattern. The pattern is shown as a row of 16 dots or numbers. A filled dot means “a sound is written here”. An empty dot means “nothing plays here”. You can also see the BPM, the FX number, and the swing percentage on the screen.

The Ravine: Phoenix firmware uses a 2.4″ colour TFT screen that displays the same information. On the real PO-33 the screen is a smaller LCD. The information is the same.

Guided exercise: a one-sound, four-step beat

You will need: a sound recorded into slot 1 (from Chapter 1), and the PO-33.

Success criteria: the sound in slot 1 plays four times per loop, on steps 1, 5, 9, and 13. Steps 2, 3, 4, 6, 7, 8, 10, 11, 12, 14, 15, 16 are silent.

  1. Make sure you have a sound in slot 1. If not, record one: hold REC + pad 1, clap, release REC.
  2. Press WRITE to enter write mode.
  3. Press PLAY to start the sequencer.
  4. Wait for step 1. Press pad 1 quickly.
  5. Wait for step 5. Press pad 1.
  6. Wait for step 9. Press pad 1.
  7. Wait for step 13. Press pad 1.
  8. Press WRITE to exit write mode.

You have just written a four-on-the-floor pattern with a single sound. The sound plays four times per loop. The loop is one bar (16 steps) long. At 120 BPM, the loop is 2 seconds long.

Editing a step

To remove a sound from a step:

  1. Press WRITE to enter write mode.
  2. Select the sound that sits on that step (hold SOUND + its pad).
  3. Press that step’s pad to toggle the sound off.
  4. Press WRITE to exit.

To change the sound on a step:

  1. Enter write mode.
  2. Remove the old sound (toggle it off as above).
  3. Select the new sound (hold SOUND + its pad), then press that step’s pad to toggle the new sound on.

To erase the entire pattern:

  1. Hold REC + PATTERN together for about 600 ms. The active pattern is wiped.

Creative challenge: write three patterns with different densities

Write three versions of the same sound. In write mode, remember the order: select the sound first (SOUND + pad), then press the step pads.

  • Sparse: the kick on steps 1 and 13. (2 hits per loop.)
  • Medium: the kick on steps 1, 5, 9, 13. (4 hits per loop.)
  • Dense: the kick on every odd step (1, 3, 5, 7, 9, 11, 13, 15). (8 hits per loop.)

Listen to each. Notice how the sparse pattern feels “open”, the medium feels “regular”, and the dense feels “busy”. The PO-33 has 16 steps, but most music uses between 2 and 8 hits per loop. Empty steps are the most underused tool in beat-making.

Listening assignment

Listen to Adonis, “No Way Back” (1986). The kick drum plays on every step (all 16 steps). This is one of the densest kick patterns in house music. It works because the kick is the only sound — no snare, no hi-hat, just kick.

Listen to J Dilla, “Stop” from Donuts (2006). The kick plays on steps 1 and 11. The snare plays on steps 5 and 13. That’s it. Two sounds, four hits per loop. Most Dilla beats are this sparse.

Listen to DJ Spinn, “Make Me Hollown” (2014). The kick plays on every step. The hi-hat plays on every odd step. The snare plays on steps 5 and 13. This is a “full” pattern — kick, snare, and hat on every step where they could possibly fit. Notice how busy it feels compared to J Dilla.

Summary and checkpoint

Key takeaways:

  • A step is a sixteenth-note. There are 16 steps per loop.
  • A slot is a stored sound. There are 16 slots — 8 drum and 8 melodic (the range order differs between the PO-33 and Ravine: Phoenix; see the Chapter 2 sidebar).
  • In write mode, select a sound (SOUND + pad), then press a step pad to toggle it on that step.
  • Most beats use 2–8 hits per loop. Empty steps are a feature.

Self-check:

  • [ ] Can you write a four-on-the-floor kick pattern (steps 1, 5, 9, 13)?
  • [ ] Can you remove a step?
  • [ ] Can you change a slot on a step?
  • [ ] Do you understand why “less is more” is the PO-33 ethos?

If you answered “yes” to all four, move on to Chapter 3.