Bristol 10k: a 2km sound system for 13,000 runners
Seamless music and speech coverage along a 2km start area, a radio microphone working 1km from the receiver, and a two-hour set-up window for the 2017 Bristol 10k.
Provide a large-format PA covering more than 2km for 13,000 runners, with high-quality music and speech, plus a radio microphone usable over 1km from the start line.
Loud Hire provided the sound for the 2017 Bristol 10k: a large-format PA that delivered high-quality music and speech with seamless coverage for 13,000 runners along an area more than 2km long, and a radio microphone that had to work more than 1km from the start line.
The challenges
Distance. You cannot simply wire up speakers in a line over that distance. Sound takes time to travel, so listeners would hear the nearest speaker before the one further away. We used careful speaker placement and audio processing to align the system so the coverage stayed clean.
Cable runs. Standard pole-mount speakers run at high impedance, and cable runs over 80m cause power delivery problems between amplifier and speaker. We deployed secure amplifier rack cases every 70m, each with signal and power in and out.
Radio microphone range. Radio microphones are normally only recommended up to 100m from the receiver. We needed 1,000m. Using four high-gain omnidirectional antennas through a true-diversity receiver, spaced 200m apart, we achieved a reliable link between microphone and receiver.
Time. The road to Canon’s Marsh closed only three hours before the race, leaving us two hours to set up. We brought in extra freelance crew who received a two-hour briefing the day before, and designed and made cable looms in advance to cut cable-laying time.
We also set up a PA system in Millennium Square for the artists and entertainment running throughout the day.
