This was fictionalised in the film Bohemian Rhapsody which showed the band’s manager Jim Beach (rather than their sound engineer Trip Khalaf) ripping off the tape over the sound level controls to boost Queen’s volume.
This did not happen, nor was Khalaf ever able to “whack up the sound level.”
Express Online spoke to Malcolm Hill, whose company Hill Pro Audio was in charge of the sound systems at Wembley Stadium for Live Aid. He even received a formal letter from the Greater London Council commending them for maintaining the strict sound levels put in place.
He told Express Online: “Nobody on or around the stage would have had any control of, or even knowledge of, the sound system operation… The system was controlled by a ‘processor rack’, 100 metres away, in the middle of the pitch, tucked out of the way, to the side of the mix platform.”
However, Queen DID actually sound louder…