Brian May's guitar tech shows us the Queen guitarist's onstage setup. May's rig incorporates three Vox AC30s, positioned at an angle and pointed off stage to slightly isolate the sound. "We have to stop the nasty reflections," May's tech says at (27:35). According to May's tech, "the center amp is straight through the rack, so there's no effects on the center amp. The wet stuff is all wet on the left and right [amps]."
“I went with Tim Staffell, who was our singer in Smile, and Roger I think, to a shop called Take Five in Tin Pan Alley that was full of second hand amps, including a few AC30s. "By that time I had a Rangemaster treble booster – I thought that if it worked for Rory it would work for me – so we pulled a few out, plugged in, and there was the sound. “I traded in my Burns transistor 60-watt amp and bought two 30-watt AC30s.They were very beaten up but sounded perfect, with that deep, throaty sound, and that was it forevermore for me.” You can also see May talking about the AC30 in this video: https://www.youtube.com/watch?v=vyyTBeAmZIc.