When a fill or delay speaker sits farther from the audience than the main, its sound arrives late, causing echo and comb filtering. The fix is to delay the closer speaker so both arrivals line up. The delay equals the distance between them divided by the speed of sound. Enter your distance below for the exact value in milliseconds and samples.
How to calculate speaker delay
Delay time is simply distance divided by the speed of sound. At 20°C sound travels about 343 m/s (1,126 ft/s), so every foot of extra distance needs about 0.89 ms of delay, and every meter needs about 2.9 ms. Measure from the main speaker to the delay speaker, enter it above, and set your DSP, AV matrix, or amplifier to the result. For time-aligning to a live source on stage, measure from the source to the delay speaker instead.
Milliseconds per foot and per meter (20°C)
| Distance | Delay |
|---|---|
| 10 ft (3 m) | ~8.9 ms |
| 25 ft (7.6 m) | ~22 ms |
| 50 ft (15.2 m) | ~44 ms |
| 100 ft (30.5 m) | ~89 ms |
Frequently asked questions
What is speaker delay and why do I need it?
When a second speaker sits farther from a listener than the main, its sound arrives late and causes echo or comb filtering. Delaying the closer speaker lines up both arrivals in time, so the system sounds clear and localized to one source.
How do I calculate speaker delay time?
Divide the distance between the speakers by the speed of sound (about 343 m/s at 20°C). That is roughly 0.89 ms per foot or 2.9 ms per meter.
What is the Haas effect and should I add an offset?
If two identical sounds arrive within about 5 to 35 ms, the ear localizes to the first arrival. Adding a small extra offset (commonly 10 to 15 ms) beyond the exact time-align keeps the audience perceiving the sound as coming from the main source, not the nearby delay speaker.
Does temperature affect speaker delay?
Yes. The speed of sound rises with temperature (c = 331.3 + 0.606 x T in Celsius). Warmer air is faster, so it needs slightly less delay. Small indoors, but worth setting for outdoor events.
Should I set delay in milliseconds or samples?
Use whichever your processor accepts. This calculator gives both. Samples depend on the sample rate, so confirm your system rate (commonly 48 kHz).
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