Locking a TidalCycles delay sets its time in cycles so echoes stay in phase with the tempo

In TidalCycles, enabling the lock flag on a delay sets its delay time in cycles rather than seconds. A delay time of 0.25 then means a quarter of a cycle, so every echo lands on a musically aligned subdivision regardless of tempo. Without locking, the delay stays in wall-clock seconds, so changing the tempo (e.g. setcps) leaves the echoes drifting out of phase with the pattern. Locking is valuable live: the performer can speed up or slow down and the delay tracks the new tempo immediately, preserving rhythmic echoes without manual recalculation.

Examples

d1 $ s "arpy*2" # delay 0.7 # delaytime 0.25 # lock 1 # delayfb 0.6
-- quarter-cycle echoes, locked to Tidal's tempo

Assessment

Explain what happens to echo timing when you change setcps with an unlocked vs a locked delay, and give a case where you would deliberately leave it unlocked.