The convention center had front mains and four delay rings hanging at 15-meter intervals down the 60-meter hall. The theory was sound: time-align each ring to the main PA so that every seat hears a coherent signal. The practice was less sound — literally — because the AV technician set all four delay rings to the same 200ms delay instead of progressively increasing delays based on distance.

The front third of the room heard the mains clearly, with the first delay ring arriving 200ms late — well above the 50ms threshold where the brain hears a distinct echo rather than a reinforcement. Every sentence had a shadow. "Welcome to the conference" became "Welcome to the conference... to the conference." The middle of the room heard the mains, delay ring one, and delay ring two all arriving at different times. The back of the room experienced a four-fold cascade of echoes that made the speaker sound like she was addressing them from the bottom of the Grand Canyon.

Delay speakers must be time-aligned to each listener position such that the delayed signal arrives within 20-30ms of the direct sound from the mains. The Haas effect ensures the brain attributes localization to the first-arriving sound if the delay is under ~35ms. Above that, it's perceived as an echo.

Delay values should equal the propagation time from the mains to each ring position, minus a few milliseconds to keep the mains perceptually dominant.

The Moral: Delay speakers are precision instruments, not volume extenders. Use SonaVyx Transfer Function impulse response to measure arrival times at each delay position and set timing correctly.