Mics on Broadway

Different types of mics are used for a variety of reasons - it can be either aesthetic or function, depending on what the director and sound engineers are trying to achieve.

Here's a cool video about the mics in the San Francisco production of Hamilton - it explains the different mics in the show and how/why they're used.

https://www.youtube.com/watch?v=351DxQghbh0&t=69s

For rock shows and things with loud accompaniment, the “Rent mics” get the mic closer to the actor’s mouth which gives a stronger direct vocal signal and can be more easily controlled. The forehead mic would need to be turned up to the point of distortion to get the voice over a loud band and you’d have a lot of “bleed” in the mic (meaning other sounds besides just the voice that get picked up) since it’s so much farther away from the mouth.

I’ve done more than one rock show with directors who insist that don’t want the Rent mics for visual reasons who then frantically switch to them during tech when it turns out the sound designer was right and the forehead mics don’t do the job, even with the band turned way down.

I believe shows which have their band on the stage require these kinds of mics. I could be wrong, though.

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If you can't mix the orchestra separately and the show has a louder (typically contemporary) score, the mic over the ear is going to give you the most control over the actors' sound. I always go with the cheek at high school shows since the orchestra is usually right in front of the audience. When I can mix the orchestra separately, I'll let the style and technical demands of the show determine where the mic goes.

You're going to get a louder input by putting the mic on the cheek, but you have to EQ the sound more to make each singer sound their best. You get a more natural sound putting the mic on the forehead, but you have to worry more about the volume difference between speaking and singing.