Behind The Mixer

Learn Church Audio Artistry | Church Sound

Vocal microphones and the accompanying users are the most important pieces of a church service.  A “vocalist” leads the congregation in worship.  The pastor leads the congregation in presenting the Word.  For these reasons, vocal microphone choice and EQ sculpting are of utmost importance.  Consider this your resource page for vocal microphones and EQ’ing vocals.

Vocal Microphones

Microphones are not the same.  Each make and model of microphone has properties and characteristics that affect its sound.  For example, two different vocal microphones used by the same person can product a different colorization of their voice.  One microphone might pick up more sounds on the stage than the other.  One microphone might be great for a solo singer while another microphone might be great for multiple singers sharing the same microphone.

There are four microphone properties;

  • Microphone Type
  • Microphone Polar Patterns
  • Microphone Frequency Response
  • Microphone Diaphragm Size

Let’s dig into each one

1. Microphone Type

There are three types of microphones; dynamic, condenser, and ribbon.  In the case of on-stage vocal microphones for the vast majority of churches, these are dynamic microphones and condensers.

Dynamic microphones are the most versatile for two reasons:

  1. They tend to hold up to heavy use (read abuse).
  2. Can handle loud volumes without distorting (think of people shouting into them).
  3. They provide a high gain-before-feedback property to get the highest level of audio signal from the microphone before it feeds back.

Photo provided by banco – CCSA

How They Work

Dynamic microphones use a thin metal coil for detecting sound. A principle of electromagnets is that as a magnet (#4) is moved within a coil of wire (#3), an electrical current (#5) is generated in the wire. The dynamic microphone uses a diaphragm (#2) attached to a coil of wire. When the diaphragm vibrates in response to incoming sound waves (#1), the coil moves back and forth past the magnet. This creates a current in the coil which is channeled from the microphone.  Because of this design, dynamics are the least sensitive of the microphone types.

This is where the trade-off occurs.  A dynamic microphone can handle high volumes, such as when the youth group uses the sound system for a rally and kids are screaming into the microphone.  However, they aren’t as sensitive to picking up the more subtle sounds in a singer’s voice.

Enter the Condenser Microphone

Condenser microphones are different than dynamics as they:

  1. Provide a stronger signal than a dynamic microphone.
  2. And are more sensitive and responsive and thus are the preferred microphone type where fitting.

The phrase “where fitting” is a conditional clause as there are instances where condensers are not the best. For example, they aren’t a good choice in high volume settings where they would easily distort the sound and possibly be damaged.  However, if you gave a condenser microphone to a trained singer, in the right environment, you would get a much better sound than a dynamic microphone.

How They Work

Photo provided by banco – CCSA

A condenser microphone’s capacitor, an electronic component which stores energy in the form of an electrostatic field (see image), has two plates (#2 and #3) with voltage between them. One of these plates is a very lightweight material and acts as the diaphragm. The diaphragm (#2) vibrates when struck by sound waves, changing the distance between the two plates and therefore changing the capacitance. Therefore, when the plates are closer together, capacitance increases and a charge current occurs. When the plates are further apart, capacitance decreases and a discharge current occurs.  #4 represents a power source and #5 represents the electronic resistance.

They are more sensitive than dynamics because it takes less energy to move that plate compared to the dynamic’s design.

Another difference between the dynamic and the condenser is the need for a charge in the condenser.  It’s for this reason that condenser microphones require power.  Power usually comes in the form of a phantom power or in some cases, a battery inside the microphone.  Phantom power (labeled as +48 V on most audio equipment) is a method of sending DC voltage through microphone cables. It is best known as a power source for condenser microphones, though many active DI (direct input) boxes also use it.

2. Microphone Polar Patterns

Microphones capture sound differently based on the source of the sound in relation to the head of the microphone.  The area in which it captures sound is known as the polar pattern.  These polar patterns show the regions around the microphone where the microphone will detect sound.  The reason for these different types of patterns is to provide microphones that work best in specific environments or to get a specific sound.

For example, if you have a crowded stage, do you want the vocal microphone to pick up sounds all around the microphone or just where it’s pointed?  You’d want to pick up only the sound of the singer, not the singer plus the person next to them.  But what if you had a quartet that all shared the same microphone?  That’s the reason for the different polar patterns.

Additionally, polar patterns can be used for capturing ambient sounds other than the primary source.  For example, in a small room, a hyper-cardioid might be used to capture the sounds in the room to provide more of a ‘live‘ feel.

The polar patterns below can be understood when you view the circular chart as arrows coming from the center of the circle.  Pointing up would be directly in front of the microphone.  Left and right represent the sides of the microphone while pointing down would be behind the microphone.

Here are the four common polar patterns:

Omni-directional (all around the microphone)

Cardioid (named so because of the heart-shape. Pick up primarily in the frontal section with reduced pickup on the sides.)

Hyper-cardioid (slightly smaller pickup areas than the cardioids plus pick up some sounds behind the microphone).

Shotgun (very directional direction)

3. Microphone Frequency Response

Microphones differ in how they respond to frequencies.  One microphone might boost a frequency where another might reduce it.  It’s usually based on the purpose for which the microphone was designed.  Some microphones might not alter frequencies at all, in which case the microphone is known to have a “flat” response.  A “flat response” microphone is one that is equally sensitive to all frequencies – these are usually reserved for studio work so engineers have maximum control.

There are hundreds of microphones on the market.  Even looking at ONLY vocal microphones, there are differences in how each manipulates the frequencies.

General vocal microphone characteristics are:

  • Vocal microphones tend to roll off bass frequencies under 200 Hz.
  • They tend to roll off frequencies above the 10 kHz range.
  • Yhey tend to have bumps in the 3 kHz – 9 kHz range.

As an example of how much they can differ, look at the frequency response chart of the BlueMic Encore 200 vocal microphone compared to the Shure SM58.

EnCore 200

 

SM58

What type of frequency response is best for your needs? 

It depends on who is singing or talking into the microphone.  One person might benefit from the Encore 200 while another person might find it negatively affects their voice.  I should add that performing EQ on a person’s voice can create a great sound, however, using a microphone that’s fitted for their natural voice can do two things; give you a significantly better sound for your baseline mixing and even give you an overall better sound that you could not achieve through mixing.  This is the live environment, so you don’t have hours and hours to perfect a vocal EQ.

As a quick note, The Complete Guide to Mixing Vocals goes into far more detail in all of these areas.

4. Microphone Diaphragm Size

The diaphragm is the portion of the microphone that receives the sound waves.  It’s the tiny plate that first moves when sound waves hit it.  It’s listed in the microphone spec’s as either a:

  • Small,
  • Medium,
  • Large.

Nothing complex, at first glance.

However, the size of that plate and how it’s made directly contributes to five properties of the microphone;

  • Natural noise of the microphone (what you hear coming through the microphone when the channel is on but no one is talking or singing into it)
  • Volume handling capability (how much volume it can handle before distortion or clipping)
  • Frequency sensitivity (how well it detects different frequencies)
  • Frequency range (the range of frequencies it can detect, especially off-axis)
  • Dynamic range (The difference between the natural noise level and the amount of sound it can pick up before distortion/clipping.

You’ll find a link below that describes the diaphragm properties in detail.

There are trade-offs between one benefit versus another. 

For example, a large-diaphragm is more sensitive to sound frequencies but it can’t handle as large of a sound volume as a small-diaphragm microphone.  Just like picking the microphone with the best frequency response for a specific singer, picking the right diaphragm size comes down to how you’ll be using it and who will be using it.

5. Microphone Sensitivity

Sensitivity is a HOT topic.  It explains why you might think a microphone is hotter than another.  There’s a reason for it and you can check it out here. That article details sensitivity specs and how to read them.  In short, microphone sensitivity is the measure of the microphone’s ability for converting acoustic pressure into an electric voltage. The higher the sensitivity, the less amplification required to bring the sound to a useable level on the mixer channel. Think of it like this, if you have a soft-spoken pastor, you want an extremely sensitive microphone.

Picking the Right Vocal Microphone

As you can see, there are several factors you need to consider when picking  a vocal microphone.  Consider it the practice of “pairing microphones.”  Pairing microphones is the process of picking the best microphone for each person based on their vocal qualities and which microphone creates the best sound for their unique voice.

You can start by pairing existing microphones with your singers.  Take time during the sound check to try different microphones with the same person.  Once you find the best, make a note of it somewhere such as a “Microphone Pairing” page that you post in the sound booth.

The next time you are ready to upgrade microphones or add more because of more singers, remember this pairing process.  While an online music store won’t let you demo a microphone, look to your smaller stores and even your fellow church techs for help.  You might have a church tech in your same town who can let you borrow a couple of microphones to try out with your singer.

When it comes down to it…pick out a vocal microphone that meets your needs.  Use it because it’s the right one for the job.

Vocal Microphone Links

Vocal EQ’ing