A New Use for Aluminum Foil

Break Interference with Aluminum Foil: 

Recently, Oncore AV was hired to help manage the stage at a major outdoor music festival with 40,000 people in attendance. There were the usual challenges faced with outdoor venues, but there was one specific challenge that was unrecognizable until after the set up was in place.CellTowerTwo major wireless cell phone carriers installed temporary remote cell tower antennas in order to facilitate the large audience with their smart phones in a small concentrated area. While the team was setting up for these major national acts, the monitor engineer noticed a high-pitched noise in his ear monitors, but couldn’t nail down where the sound was coming from.

We determined that guitar amplifiers are highly vulnerable to these radio frequencies considering it’s an unbalanced device with a large open area that is unprotected against radio interference. In most cases, the interference is not recognized inside buildings due to the filters of brick walls, concrete or wooden structures that attenuate the high-frequency, high-pitched digital radio waves.

To stop the interference from the cell tower, we took a quick trip to catering to get a roll of aluminum foil and placed it between the cell tower and the amplifier, acting as a shield and the interference went around the amplifier itself. Although aluminum foil is an easy fix, it didn’t eliminate the sound completely. It definitely attenuated the interference of the amplifier by 20-30 dBs. This was unrecognizable to the in-ear monitor system and the multi-thousand watt sound system for the audience.

If we can hear this complication audibly, then the question should arise, where does the responsibility lie? For us, the solution was just as simple as aluminum foil, but for the public, there’s definitely a need for concern. Does the cell tower owner need to adjust its antennas, power level or positioning of the remote towers; or is it the responsibility of the amplifier owner and the sound company to protect its equipment from this interference? It’s up for debate, you decide, and leave your comments below!


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