Greatful Dead Movie

[mario_farufyno]

I'm pretty sure you all know that footage, but for me was the first time I "saw" a Dead show...

[mario_farufyno]

Can someone explain me Jerry's microphone?

[rv_bass]

I’m Not a sound engineer, but my basic understanding is that they are noise canceling microphones, one delayed slightly from the other, to prevent feedback from the wall of sound speakers bleeding into the vocal mics. They sang into the top mic, and the bottom one was delayed to cancel out other sounds. So, your noise canceling headphones can thank Alembic and the Grateful Dead.      Here’s a link to a google search on the topic:

https://www.google.com/search?q=wall+ofsound+microphones&ie=UTF-8&oe=UTF-8&hl=en-us&client=safari

[lbpesq]

I don’t believe there was any delay involved with the mic.  Rather, they were a pair of mics wired out of phase, so anything they both picked up, like the WOS behind them, was cancelled.  The singer sang into one mic only, so their voice, being picked up by one of the pair but not the other, came through without being cancelled.  Simple, but ingenious.  Hmmmmm, sounds like Ron and Alembic!

Bill, tgo

[mario_farufyno]

Thanks Rob and, yes Bill, you're right, it seems to be a clever use of phase cancelation.

As background noise is the same for both microphones, they can be almost tottaly canceled out by flipping phase in the secondary mic while the mouth is much closer to the "main" mic (almost touching it, in fact) and spaced by few inches from the inverted mic, can make the voice enough distinct between the two mics to not being canceled by phase invertion. Brilliant.

[mario_farufyno]

Probably more effective on highs above 2K or the chin somehow also dampens the inverted mic, making it behave more like a Gate when the head moves away from it. Amazing concept, since a Noise Gate wouldn't be much usefull with a sound reinforcement just behind the mics.