How do you use delay speakers in live sound?
Quick answer
Delay speakers are used in live sound to synchronize audio from secondary speaker positions with the main PA, compensating for the time it takes sound to travel, ensuring coherent coverage for distant audience areas.
In live sound, delay speakers are positioned further from the stage to cover areas where the main PA's direct sound arrives late or is attenuated. The key is to align them temporally: the delay time is calculated based on the physical distance from the main speakers, typically using a measurement system like SMAART or a delay finder. This ensures that sound from the delay speakers arrives at the listener's ears at the same time as sound from the main PA, preventing comb filtering and intelligibility loss.
SSOUNDS engineers approach delay systems with precision: after measuring the distance from the main PA to the delay position, we set the delay time (in milliseconds) equal to that distance divided by the speed of sound (approx. 343 m/s). We then use our DSP presets to align phase and level, often applying a high-pass filter to reduce low-frequency overlap. Properly deployed, delays extend coverage without compromising clarity, making them essential for large venues, outdoor festivals, or long-throw applications.
Key things to consider
- Measure the distance from the main PA to the delay speaker position to calculate delay time (distance ÷ speed of sound).
- Use a real-time analyzer (RTA) or measurement software to fine-tune alignment and ensure phase coherence.
- Apply a high-pass filter to delay speakers to avoid low-frequency buildup and interference with subwoofers.
- Set delay speaker levels to match the main PA at the crossover point, typically 3-6 dB lower for seamless blending.
- Position delays to cover shadowed areas (e.g., under balconies, far field) without overlapping the main PA's coverage zone.
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