Speaker Delay Alignment Calculator

When two loudspeakers covering the same area are at different distances from the listener, their sound arrives at slightly different times, causing comb filtering and a smeared image. Adding electronic delay to the nearer speaker so that both arrivals coincide aligns them in time. This is standard practice for subwoofers, fill speakers and distributed sound systems.

Delay equals the path-length difference divided by the speed of sound: delay (s) = distance difference (m) / speed of sound (m/s). In milliseconds, multiply by 1000. The nearer speaker is delayed by this amount so its sound leaves later and arrives at the same instant as the farther speaker's.

The speed of sound in air depends on temperature: c = 331.3 + 0.606 * T m/s, where T is the air temperature in degrees Celsius. At 20 C this gives about 343.4 m/s. This calculator uses your entered temperature so the delay is accurate for the actual conditions, which matters for precise alignment outdoors or in hot venues.

Sound travels roughly 0.343 m per millisecond at 20 C, or about 1 ms per 0.343 m (about 1 ms per foot is a common imperial approximation). So a speaker 3.43 m farther away than another needs about 10 ms of delay added to the nearer one at room temperature.

Always delay the speaker that is closer to the listener, because its sound would otherwise arrive first. You add just enough delay to match the arrival time of the farther speaker. Delaying the farther one would only make the misalignment worse, so the calculator's result is the delay to apply to the nearer source.