Speaker delay calculator

Enter the extra distance from the main speakers to the listener, compared with the delay speaker. Get the delay in milliseconds and samples.

How it works

At 20 °C (68 °F) sound travels about 343 m/s, roughly 1.13 ft per millisecond, or about 0.89 ms per foot. 60 ft of path difference is about 53 ms.

The precedence offset adds a few milliseconds on top so the delay speaker arrives just after the mains. Listeners then localize to the stage instead of to the speaker overhead.

Field notes

• Measure the path difference, not the distance between speakers. Pick a listening spot in the delay zone. Measure from the main speaker to it, then from the delay speaker to it, and subtract.
• Precedence offsets of about 5–15 ms are common for under-balcony and delay towers. Keep the delay speaker's level within about 10 dB of the mains at that seat, or the offset won't hold the image.
• Temperature matters on big throws. At 100 ft, a 20 °F swing moves the right delay by about 2 ms. Outdoor shows drift between soundcheck and showtime.
• Check with a measurement. A dual-FFT impulse response (Smaart, REW, Open Sound Meter) beats a tape measure, especially for subs and fills with processing latency of their own.
• Livestream mics picking up the room have the same problem. Delaying the board feed to line up with the room mics follows the same 1 ms per foot rule of thumb.

FAQ

Why not just use 1 ms per foot?

It's a handy estimate that's about 12% high at room temperature. For short distances it doesn't matter. At 100 ft it's off by about 11 ms.

Does humidity matter?

Barely. Humidity changes the speed of sound by well under 1% at normal temperatures. Temperature is the big factor.