Polyrhythm Metronome & Odd Time Signatures
A regular metronome clicks one pulse. This one clicks two or three at once, splitting the same bar into different numbers of beats: in 3:2, cycle A plays three times while cycle B plays twice, and the first beats of both line up. Each cycle has its own sound (woodblock, beep, clave or snare), its own volume and its own color on the grid, so you can hear and see where the beats meet and where they drift apart. You can mute one cycle and try to keep it in your head while the other keeps going.
How to use it
- Choose Polyrhythm mode and tap a preset (3:2, 4:3, 5:4, 7:4...). For any other combination, open Cycles, sounds and subdivision and set the pulses for Cycle A, Cycle B and, if you like, a third cycle.
- Set the tempo with the number field, the −5/+5 buttons or Tap. In polyrhythm mode the BPM belongs to cycle B, the base pulse: in 3:2 at 120 BPM the 2 plays at 120 and the 3 fits into the same bar.
- Press Play (or the space bar). Each cycle's row lights up on its beats and a cursor sweeps across the bar; start by tapping only the cycle with the bigger cells, then try both hands.
- For odd meters, switch to Odd time, tap 7/8 or 5/4 and pick a grouping (2+2+3, 3+2+2...). The start of each group is accented and the downbeat is louder still. Other meters and groupings are in the settings panel.
- Under Cycles, sounds and subdivision change each cycle's sound, turn one down or mute it (keys 1, 2 and 3). Use Copy link to this setup to send the exact combination to a student or bandmate.
Help and explanations
The second mode is for odd time signatures. In 7/8, 5/4, 9/8 or 11/8 counting to seven is not enough: what matters is how the pulses are grouped. Choose 2+2+3, 3+2+2 or 2+3+2 and the metronome accents the start of each group, with a stronger click on the downbeat. The grid shows the count inside each group (1 2 1 2 1 2 3), which is how drummers and bass players think about these meters. Everything runs in your browser and nothing is uploaded.
How to learn 3 against 2 (and 4 against 3)
The classic trick for 3:2 is to count the smallest shared subdivision. Three against two fits into six parts: the 3-cycle lands on parts 1, 3 and 5, the 2-cycle on parts 1 and 4. The grid makes this obvious because the cells of both cycles are drawn on the same ruler. Start slowly, around 60 BPM, with both cycles audible, and play the 2 with your foot and the 3 with your hand. Once it feels comfortable, mute the 3 and keep playing it against the 2 alone; then swap.
For 4:3 the ruler has twelve parts (the 4 lands on 1, 4, 7 and 10; the 3 on 1, 5 and 9) and the two cycles only meet on the downbeat, which makes it much harder to hold. If you lose your place, turn on a subdivision of 2 or 3 per pulse: the small grey marks show the shared grid and help you find the beat again.
Odd time signatures: the grouping is what you hear
A 7/8 played as 2+2+3 sounds like a waltz with an extra beat at the end; as 3+2+2 it feels like a fast tango; as 2+3+2 it becomes more lopsided. It is the same number of eighth notes, but the accents change the music, which is why this metronome accents the start of each group instead of counting seven equal clicks. In 5/4, 3+2 is the Take Five pattern; 2+3 shows up in a lot of Balkan music and film scores. In 9/8, 3+3+3 is an ordinary compound meter (like 6/8 with one more group) and 2+2+2+3 is the aksak, the "limping" meter of Turkey and the Balkans. For 11/8 try 3+3+3+2 or 2+2+3+2+2.
If the grouping you need is not among the presets, type it in the Other grouping field in the settings panel (for example 4+3 or 3+3+2+3): the parts must add up to the number of pulses in the bar. The note value (x/4 or x/8) only changes the label on screen; the BPM always counts each pulse, so 7/8 at 160 BPM means eighth notes at 160, about 23 bars per minute.
Timing accuracy and phone use
Clicks are scheduled on your device's audio clock (Web Audio), not on a JavaScript timer, so the layers never drift apart even while you scroll or another tab is busy. On iPhone the sound plays even with the silent switch on, and the screen stays awake while playing when the browser allows it. Your last setup is saved on your device; a link with ?a=3&b=2&bpm=80 opens straight into that combination without touching what you had saved.
Tips
- Give the cycles very different sounds (woodblock on one, snare on the other): your ear separates the layers far more easily than with two similar beeps.
- Turn one cycle down gradually instead of muting it all at once; when it reaches zero and you still feel it, you have internalized the polyrhythm.
- In odd meters, say the grouping out loud with syllables ("ta-ka ta-ka ta-ki-ta" for 2+2+3) before you play it on your instrument.
- For fast 7/8, tap the eighth-note pulse rather than the whole bar; if you prefer to think in bars, divide the BPM by 7.
Frequently asked questions
Is the BPM per bar or per beat?
In polyrhythm mode the BPM belongs to cycle B, the second number (in 3:2 the 2 beats play at that tempo and cycle A fits into the same bar). In odd time mode it is per pulse: 7/8 at 160 BPM means each eighth note at 160 per minute.
What is the difference between 3:2 and 2:3?
It is the same pattern with the base pulse swapped. In 3:2 the 2-cycle is the reference (the BPM is its tempo) and the 3 is the layer on top; in 2:3 it is the other way round. In practice, pick the one whose layer you want to feel as the main pulse.
How do I set up 7/8 as 2+2+3?
Switch to Odd time, tap the 7/8 preset and then the 2+2+3 chip. The first pulse of the bar is the loudest, the start of each group gets an accent and the grid shows the count 1 2 1 2 1 2 3.
Can I mute one cycle and still see the grid?
Yes. Each cycle's Mute button (or keys 1, 2 and 3) silences only its sound; the row keeps lighting up, dimmed, so you can check that you are playing it in the right place.
Can I run three cycles at once?
Yes. In Polyrhythm mode open Cycles, sounds and subdivision and pick a value for Cycle C (for example 4:3:2). All three divide the same bar and each gets its own sound, volume and color.
Does it work offline and without sending data?
The clicks are synthesized in your browser and nothing is recorded or uploaded; once the page has loaded it needs no connection. Your settings are stored only on your device.
Why does the bar restart when I change a cycle while playing?
When you change a cycle, the grouping or the subdivision, the bar restarts at that moment so every cycle begins together. Changing only the BPM does not restart anything: the bar shrinks or stretches and keeps its position.