Route your interface's LEFT output to the main PA and the RIGHT one to the delay tower. The app fires one chirp per feed, measures the real arrival difference at your spot with the mic, and gives you the milliseconds to program into the DSP.
A PA delay calculator that actually measures: instead of converting meters to milliseconds, it fires two distinguishable chirps — left output to the main PA, right output to the delay tower — captures both arrivals in the same recording and separates them by correlation (matched filter). You get the delay in ms to program into the tower DSP, the equivalent distance, and an optional +10 ms Haas precedence, with temperature correction. Everything runs in the browser; nothing is uploaded.
Why two chirps in one buffer
Browsers add tens of milliseconds of variable output latency, which ruins any absolute time-of-flight measurement. This tool never relies on absolute time: both chirps live in the same playback buffer with an exact programmed spacing, so latency shifts everything together and the difference between arrivals — the number you need — survives intact. Each chirp occupies a different frequency band, so reverberation and noise can't confuse one for the other.
Frequently asked questions
Why not just measure the distance and convert meters to milliseconds?
Distance calculators ignore what actually happens: processing latencies, tower position vs. the real coverage area, and temperature. Measuring the two real arrivals at your listening spot captures all of it in one number.
How does it dodge the browser's audio latency?
Absolute browser latency is large and variable, so the app never uses it. Both chirps are placed in the same output buffer with an exact spacing, and both arrivals land in the same recording. Latency moves everything together; the difference between arrivals — the only thing that matters — stays intact.
What do I connect where?
Left output to the main PA feed, right output to the delay tower feed (on the console or DSP matrix). Stand at the position you want to align (usually within the tower's coverage), hold the phone or laptop mic clear of your body, and fire the measurement during a pause.
What is the +10 ms precedence (Haas) option?
After time-aligning, engineers often ADD around 10 ms to the tower so the first wavefront still comes from the stage: the audience localizes the band, not the nearest speaker, with no audible echo. The app shows both values; use your preference.
How accurate is it?
The correlation locates each chirp with sub-millisecond precision in reasonable conditions (clear chirps over the noise). If a chirp is buried in reverb or noise, the app warns you and asks to repeat. For reference, 1 ms ≈ 34 cm.