How to use it
- Enter rhythm A and rhythm B, each from 1 to 12 notes per cycle, such as 3 and 2 for a hemiola or 4 and 3.
- Set the tempo of rhythm B, the beat you feel or tap with your foot.
- Read the grid: filled cells are where each rhythm plays. Below are the cells to count and the spacing in milliseconds.
- Press play to hear rhythm A as a high click and rhythm B as a low click; the current cell is outlined.
How it works
cells = lcm(A, B); rhythm A plays every cells ÷ A cells, rhythm B every cells ÷ B cells.
cycle = 60,000 ÷ BPM × B ms, A spacing = cycle ÷ A, B spacing = cycle ÷ B.
The least common multiple comes from the greatest common divisor: lcm(A, B) = A × B ÷ gcd(A, B).
Worked example
3 against 2 at 90 BPM:
- lcm(3, 2) = 6 cells;
- A plays on cells 1, 3, 5 (X . X . X .) and B on cells 1, 4 (X . . X . .); they meet only on cell 1;
- a beat of B is 60,000 ÷ 90 = 666.7 ms, a cycle of two beats is 1,333.3 ms, and the notes of A are 1,333.3 ÷ 3 = 444.4 ms apart.
For 4 against 3 the grid has 12 cells: A on 1, 4, 7, 10 and B on 1, 5, 9.
Tips
- Practise slowly with both clicks, then mute one line in your head and keep it going.
- Tap the main beat with your foot and play rhythm A with your hands.
- To set delay or echo effects in time with the tempo, use the delay time calculator.