Chapter 5. Microphones, P.A. Systems, and Troubleshooting

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Chapter 5. Microphones, P.A. Systems, and Troubleshooting

Microphones, a.k.a. mikes , are devices used to turn an acoustic signal, like a voice or a drum, into an electronic signal that can be recorded or amplified. PA systems allow the microphone to be heard .

We'll also add in a little here on repairing stuff. Because part of being a D.I.Y. musician is taking care of your own gear.

Different microphones have different pickup patterns. This refers to how they pick up sound. A cardioid (a.k.a. unidirectional) pattern is heart shaped; it picks up most sensitively from the front and the sides, but not much from behind at all. They are good for live miking of vocals.

Figure 5.1. Microphone on mike clip on mike stand.

Two mikes are commonly used for rock: The Shure SM57 microphone is better for instruments, and the Shure SM58 is the standard for vocal. Both are reasonably priced ($120 to $170 new, way cheaper used). An even better vocal mike is the Sennheiser 835, which lists for $280.

All three of these are dynamic mikes, which require no external power supply. The Shure 16AM-CHN is an example of a condenser microphone. These require a battery in the mike or line transformer/adapter/power supply box or Phantom Power (power provided by the mixing board), are more sensitive, and better for miking from further away, for instance, miking a whole drum kit from above, or for recording a band from the audience or from above the audience.

If you are using a powered mike, remember to turn the battery off when not using it or the battery will wear down faster. There will probably be a switch on the power supply box.

Figure 5.2. Generic Radio Shack mike with omnidirectional pattern drawn in.

Figure 5.3. SM58 with unidirectional pattern drawn in.

Many mikes have a switch on the side to turn the power off and on. This is useful when the mike starts to feed back. Feedback is the squeal you get when a microphone is pointed at a speaker, and the signal forms a feedback loop, getting louder and louder. You can cut this by cutting the switch off and back on or by moving the microphone away from the speaker. If you know this, you will get better at cutting it without thinking. Eliminating feedback is also the soundman's job, but do what you can from the stage to help him or her.

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