Doppio movimento
Double tempo — the beat becomes half as long.
What it means
Doppio movimento means “double motion” and asks that from the marked spot you play exactly twice as fast. The marking is thus one of the few that determine a tempo exactly: what previously lasted a quarter note now lasts an eighth note; the pulse doubles, the beat becomes half as long.
Here lies the difference from all the approximate tempo words. Più mosso asks merely for “more moved” and leaves the measure to the performer, accelerando a gradual transition. Doppio movimento, by contrast, names a ratio that can be calculated, and the change happens abruptly, not over a stretch.
The counterpart is metà movimento or mezzo movimento, that is, half tempo.
In the notation
The marking is written in italics above the staff at the point from which it applies. It is often clarified by a note-value equation in which an old note value is equated with a new one; this notation is more unambiguous than the word alone and widespread in newer editions. Occasionally a metronome number is added as well.
Musical use
The marking stands at places where a section passes into a distinctly faster one without the metric framework changing: at the transition from a slow introduction into the main part, at the beginning of a closing climax, at the change from a stately into a dance-like part. Because the ratio is fixed, the connection between the two parts remains audible — the new section is not simply fast but measurably derived from the old.
Performance practice
Calculate the new tempo before practising and set the metronome to it instead of getting faster by feel; the most common deviation is a tempo that stays clearly below double. Keep a stable pulse in the old section, for it is the reference. Practise the transition specifically: the last note of the old and the first of the new tempo must connect without a gap. In an ensemble it helps to name the divided note value together beforehand so that everyone proceeds from the same reference value.