Soundboards of that time were not set up to be tapped into in that way back in those days, and were not trusted to deliver the sound that the film maker wanted. In those days, the PA system was tuned to what the house sound and the band wanted, and film makers of the day were not an integral part of the gig. A roadie ran on with another mic so then I was holding two mics taped together and I wasn't really sure which one to sing into. "And then my microphone wasn't working, which for a singer is a bit of a handicap. I have seen footage of Bryan Ferry performing with two handheld mics, deliberately moving one or the other closer to his mouth, to achieve a stereo pan.ĭuring Live Aid, Bryan Ferry was apparently using two mics for musical effect. However this is something you'd be more likely to do in a studio than in a live setting. All the photos I've found show them in the 70s, with one mic for PA and one for recording.ĭifferent microphones do have different characteristics, and it's certainly possible to fine-tune the sound by combining signals from more than one mic - perhaps running each one through a different effects chain.
I can't find any photographs of the Grateful Dead employing this technique - so it's possible they only use(d) it in certain circumstances.
The Grateful Dead play in front of a loud backline, so they need tricks like this to deal with background sound. Most bands don't need this because they play on a reasonably quiet stage, with the PA speakers in front of them. Indeed it may be more suited to acoustic instruments, because it's reasonably easy to shove your mouth right up to a unidirectional mic - it's less easy with certain instruments. Of course this doesn't only apply to vocals - it could work for any sound source. There is some phasing-related distortion on the vocal, but in a live setting it's too subtle to matter. By combining the two, with reversed phase, (background noise minus background noise = silence), (vocal from closer mic minus vocal from further mic = audible vocal).
The signals from the two mics contain almost identical levels of background noise, but one has a louder version of the vocal than the other. That's quite a different physical arrangement to the one in your photos. In this arrangement two omnidirectional mics are set up so that one is a few inches further from the wanted sound source than the other. The output of the two mics is combined with equal levels but opposite polarity. The Grateful Dead are known to use two mics as a noise cancelling technique. Either they didn't have mic splitters or they didn't trust them! This was a very common way of doing things in the 70s.
In these pictures it's likely that one mic is for the PA and the other mic is for recording.