Microphones
Microphones are the most basic, essential tool for running sound each week, so it pays to know just a bit about what makes them unique, what makes them tick, and what to do with them. Here are a few fundamentals of the different types and some pointers on using them effectively for worship services.
There are two primary ways we can design a mic to convert an acoustic soundwave into an electronic signal. You don’t need to know the gritty details, but you do need to know a few characteristics that make a difference on stage. Condenser mics follow a capacitor-type principle for transducing sound waves. What that means to us is that they require phantom power (the +48V button on the channel) and they are far more sensitive than other types of mics. Condensers pick up everything around them, including other singers, musicians, monitor wedges, and the main speakers. Feedback is more of a problem with these mics, and so we generally tend to use them only for certain things such as head mics, piano, drum overheads, choirs, and so forth.
Dynamic microphones are based on electromagnetic induction; move a coil of wire within a magnetic field and it generates an output voltage. Inside the mic is a diaphragm attached to a coil of wire; sound hits the diaphragm, moving it within that magnetic field. In practice, dynamics are less sensitive than condensers, so they work well in live situations with lots of things going on. The converse of this is that they don’t pick up from farther away, so you have to place them fairly close to the source, probably a few inches to a foot or so. Dynamics are good for vocals (that trusty SM58), guitar amps, and drums. There are exceptions, of course, but at least if you know how they tend to behave you can make a better judgement.
The other way we select particular mics and design types is their sound; it’s like an artist’s palette full of different brushes. Condensers have a clear, articulate high frequency response, whereas dynamics are a bit duller on top. Dynamics can sound punchier, which makes them good for drums. The diaphragm size is important as well; notice some mics are fat, others pencil thin. Think about your stereo speakers at home and notice there are at least two different speaker components: the smaller one handles high frequencies (very scientifically named tweeter) while the larger one handles bass frequencies (also cleverly designated the woofer). So, don’t put a thin mic, like a 58, in the kick drum; you’ll get very little bass.
Mics are also designed to pick up sounds from a particular direction. Most often for live situations we want to use uni-directional, or cardioid, meaning they pick up from the front, less so from the edges and rear. It’s not a total cutoff point, though. Sounds coming into the sides and rear are comb-filtered, meaning the mic is trying to get rid of that stuff, but can’t do it completely. Some frequencies will be attenuated, others not so much depending on the relationship between distance and frequency-related wavelengths, resulting in an unnatural sound (the term is off-axis coloration). Find out exactly where the front of the mic is and point that at the source.
For live situations, the challenge is that you’ve got lots of sources on stage making noise. All of this adds up, so we want to minimize sound being picked up by multiple mics. Follow these guidelines:
Keep the mic close to the source. The mic will tend to only pick up that source. It also allows you to run lower levels on the console; when you don’t have to crank it up as much you lower your threshold before feedback. So, keep it close. Train your vocalists and leaders on how to hold the mic properly so it’s not hovering about their waist. Consider this: every time you double the distance between a mic and its source, the level drops roughly 4-6dB (the math indicates 6; it’s a bit fuzzier due to variables in real life). So from two inches from the mouth out to four, you’ve already lost several dB that have to be compensated for by turning up the preamp and fader. That really adds up, so pay attention to distance—it can be your friend rather than a total nightmare.
Point the mic directly at the source; find out where the front is located on the grill. Otherwise it’ll sound weird coming in the side while also picking up the trumpet dude over there with remarkable clarity…
Mute mics whenever not in use. Always. Don’t leave open mics as they will pick up stuff and add garbage to your mix, contribute toward feedback, and just plain sound bad.
Remember: more mics = more feedback.
Use direct boxes whenever possible. Keyboards, bass, and guitars should all go direct. Avoid miking that cool guitar amp on stage (although many churches isolate the amp back stage). Electric guitars can use amp simulators, which are so good these days nobody in the congregation is ever going to know the difference. Ever.
There are lots of great mics on the market that work well for church sound. I haven’t tried to go into which mic to use on what; there are lots of sources out there for that (although admittedly mostly bad). For now, understanding some basics can help a great deal in selecting a mic and knowing how to use it.
