Production

How To Select The Right Microphone

It seems like there is a lot of mystery and mythology centered around the selection of “the perfect microphone.”

So what is it that makes a mic sound good, and how can we select the right mic for our live sound application?

Step 1: Placement

Listen. I don’t care what mic you use. If you don’t put it in the right spot, it ain’t gonna sound good.

Yes, selecting the proper mic and pattern will go a long way in helping you get great sound (we’ll talk about that next), but you need to place it in such a way that it captures the best possible sound for the instrument or vocal being miked.

This placement is going to vary depending on the source. Here are a few basic suggestions:

Vocals (handheld): The microphone should be held within 1-2 inches of the mouth to maintain good frequency response. Too close and it may sound boomy or bassy. Too far away and it may sound thin or tinny.

Vocals (choir): Use condenser microphones at a distance of 36-60”. Distance may vary depending on the size of the choir and the number of microphones used. Remember to follow the 3:1 rule for placement. If mic #1 is 1’ from the source, then mic #2 should be placed 3x that distance away from mic #1 (or 3’ away).

Electric Guitar: Place a microphone in front of one of the guitar cabinet loudspeakers, very close to the grill cloth. Mic can be slightly off-center and pointed at a slight angle toward the middle of the speaker.

Kick Drum: Place a microphone just inside of the soundhole on the front head of the kick drum. Move the mic closer to the beater head to get more smack from the drum. Move the mic farther away to capture more resonant lows and boom from the drum.

Strings: Use a condenser mic and place it about 24” above or in front of the instrument. Move the mic around to find the best overall tone, while keeping it away from the player’s bow.

Experiment with these starting points and adjust from there to find the “sweet spot” for your sound.

Step 2: Dynamic vs Condenser

There are two common types of microphones used for live sound: Dynamic and Condenser.

A dynamic mic uses a thin diaphragm to move a wire coil inside of a magnet to convert acoustic energy into electrical energy. (This is the same principle but exact opposite function of a loudspeaker, in case you were wondering.) Dynamic mic capsules do not require extra power to operate.

Condenser microphones use small plates that are electrically charged. An electrical signal is created when acoustic energy moves the plates closer together. Condenser mics need “phantom power” to operate. This is generally provided by the mixing console in the form or 48 VDC (volts, direct current).

Oh, and it’s called phantom power because dynamic microphones don’t even know that it is on the line. You can plug in a dynamic mic on a phantom powered channel, and it won’t care!

Alright, that was a little technical, but it’s important.

As a rule of thumb, use dynamic microphones for “close mic” situations like miking drums, guitar cabinets, and vocals. Use condenser microphones for distance miking applications like choir, strings, acoustic guitars, and drum overheads.

And condenser mics always need phantom power (or battery power). Don’t forget that!

Step 3: Size & Pattern

This can be a little nuanced, but it’s true that the diaphragm size of a microphone can affect the overall sound captured. Plus it can simply help the mic fit in the location it is intended.

• Large diaphragm dynamic and condenser mics are great for picking up ambient sounds and low frequencies. That’s why you’ll likely want a large diaphragm dynamic mic for your kick drum or studio/room recording applications.
• Medium diaphragm mics (dynamic & condenser) are great for things like vocals, drums, horns, and guitar amps.
• Small diaphragm condenser mics work well for strings, acoustic guitars, and overhead miking.
• Ultra-small diaphragm mics are used for lapel mics or headset mics.

While size can have an effect on sound quality, the pickup pattern of your mic will likely have a more noticeable effect when it comes to live sound.

• Omni-directional mics pick up sound 360˚ around the mic capsule. These mics tend to have limited used for live sound reinforcement because they don’t provide a very directional pickup pattern. That said it is common to see a headset, lavaliere, or piano mic using an omni-directional capsule.
• Cardioid mics are great for picking up sound around the front half of the mic, while rejecting sound from the rear of the mic. This makes them great for use where stage monitors are placed directly behind a microphone (as with vocal monitors).
• Super-Cardioid mics have a narrower pickup pattern in front of the mic, with a small rear lobe picking up sound directly behind the mic. These mics are great for capturing sound from a medium-to-long distance, so long as there are no stage monitors or loudspeakers directly behind the microphone.
• Hyper-Cardioid mics have a very narrow front pickup pattern, but a slightly larger rear lobe behind the mic when compared with a super-cardioid mic. These mics are great for long-distance miking needs, or where significant side rejection is required in noisy environments. (I’ve had to use hyper-cardioid shotgun mics for some choir miking applications.)

Selecting the right microphone pickup pattern will help you capture the sound you want, while rejecting the sound around the mic that you don’t want.

Experiment & Listen

There are plenty of other technical things that can contribute to the sound quality that comes from your microphones, but getting these three steps right will go a long way in delivering good results regardless of the mic you choose.

Remember, there are no one-size-fits-all rules when it comes to mics and mic placement. Experiment. Listen closely to the instruments and vocals being miked. Try to capture the most natural sound possible.

Yes, you may need to apply some EQ to the input channel, but there is no substitute for good mic selection and proper mic placement. Spend some time to get it right and you’ll have a better sounding mix!

JAMES WASEM

Author / Audio Engineer
Great Church Sound | Missoula, MT
greatchurchsound.com

James Wasem has been fascinated by sound and electricity from an early age. His love of music and technical gear made sound engineering and systems integration a natural pursuit. James has spent the last 20 years performing and touring in bands as a drummer, mixing live sound for churches, schools and theatres, and working as an audio systems installer and designer.

Though involved in highly technical fields, James has a passion for making things simple to understand and easy to use. It was from this passion that the book Great Church Sound – a guide for the volunteer was born. James believes that technical ministry volunteers provide a critical service for their congregations and should be well equipped with quality tools to help them grow in craft, skill, and spirit.

James and his wife Kate (who also provided the illustrations for Great Church Sound) live in the beautiful Rocky Mountains of Missoula, Montana.