By Bob McCarthy • January 3, 2019 After the system was properly tuned we set to work on Lily’s microphone. It was here that we first invented the technique for tuning a body-mounted lavalier mic placed on the actor, using her voice as the source. The technique involves taking a transfer function measurement of the difference between the electrical signal in her mic cable and a B&K 4007 omnidirectional mic placed a meter or so in front of her. Lily would talk through the various characters and the response of her chest-mounted mic would reveal itself on the screen. This technique is still applicable with any body mic on the market today. We traveled together as the show appeared at various venues over the following months. Somewhere along the way I was told of the great crossover fable and was warned to steer clear of the issue should it arise. The fear was that if the actual crossover frequency were to be revealed she would make us take down the PA. I made no promise to play along. The Showdown It was just another day of mic check and things were pushing along unhappily. What’s up? What changed? Did you do something different? All of the usual questions that artists ask of technical people who know never to change anything when they know this question will be asked. So there we all are – me, the lighting designer, tour manager, road manager, mix engineer, and Mark Johnson of Meyer Sound. Why so many? Remember, everybody’s a sound critic. Lily is stumped. Nothing sounds right today. So she asks the question: “What is the crossover for these speakers?” The silence was deafening. Pause. “1,200 Hz,” I replied, to which she responded: “Oh my God! How the… I thought we… What about my voice? I thought it was supposed to be 800.” Five people ducked under their seats. I walked up to the stage to address Lily directly and privately. She spoke first: “I don’t know what a crossover is, but everybody makes a big deal about it.” I answered, “I don’t know what it was that people have told you, but a crossover is a technical matter between loudspeaker transducers (a woofer and a tweeter) and your voice does not have a crossover. Every speaker is designed with a crossover that best suits the particular woofer and tweeter that it has, not for a particular person to talk through.” “Well, thanks,” she said. “That never made any sense before anyway. I knew everybody was bulls—ting me on that,” and with that, the sound check continued, focusing instead on what was really happening rather than chasing ghosts. The body mic equalization technique as described in the text. The artist speaks and the voice arrives at both the measurement mic (the reference response/input) and the body mic (the measured response/output). The difference in arrival time must be compensated and the actor must maintain a fixed position with regard to both mics. This transfer function approach is inverted from the typical measurement for tuning sound systems (where the measurement mic is the output). After the body mic response is found, equalization can be applied and the results will be visible in the transfer function. The technique incorporates the response of the mic in place on the actor inclusive of hats, etc. Read the rest of this post 1 2 3 About Bob Bob McCarthy Director of System Optimization, Meyer Sound Bob has been designing and tuning sound systems for over 30 years. The third edition of his book Sound Systems: Design and Optimization is available from Focal Press. He lives in NYC and is the director of system optimization for Meyer Sound. Tagged with: Bob Mccarthy Business Leadership Lily Tomlin Loudspeaker World John Meyer Management Meyer Sound SIM Techniques The Search for Signs of Intelligent Life in the Universe · all topics Subscribe to Live Sound International Subscribe to Live Sound International magazine. Stay up-to-date, get the latest pro audio news, products and resources each month with Live Sound.