Speaker Delay & Time Alignment Calculator

How it works

c = 331.3 + 0.606 × T (°C) m/s · delay (ms) = distance difference (m) ÷ c × 1,000 · samples = ms × sample rate ÷ 1,000 · ≈ 2.9 ms per metre, 0.88 ms per foot at 20 °C

Sound takes about three milliseconds to travel a metre, so when the same signal reaches a listener from two speakers at different distances, the nearer one arrives early and the ear hears comb filtering, smeared transients and an image pulled toward the nearer box. Delaying the near speaker by the travel time of the path difference makes the two arrivals coincide; sound engineers then add a few extra milliseconds so the main stack arrives first and, thanks to the precedence effect, the audience still localises the sound to the stage even though the fill is louder at their seat. The speed of sound rises with temperature, so a delay set at a cool afternoon soundcheck is slightly wrong in a hot hall, and subwoofers with digital processing add latency that must be treated as extra distance.

Worked example

A delay tower 3 m from a listener who is 25 m from the main stack has a 22 m path difference; at 20 °C sound travels 343.4 m/s, so the tower must be delayed 64.1 ms, plus a 10 ms Haas offset — 74.1 ms, or 3,555 samples at 48 kHz. If the evening warms to 30 °C the same 22 m takes 1.1 ms less.

Frequently asked questions