Understanding Microphones Part 1

Microphones are where it all begins and Part 1 is where this series begins!We are taking an in-depth look at microphones from all angles, but without the deep technical jargon. I will explain things in real world terms that won’t require a college degree or a dictionary to understand. When we are done, you will know how to use each type of mic, understand why they work the way they work, and be able to read the technical information that comes with a mic to see the virtues and vices of each and every mic you encounter.

Here we go.

There are only 2 types of Microphones!

See how simple that is?

Take a look at these.

Ok, That’s it. We’re done, have a great day!

What? You need to know more? Just kidding.

There are only 2 types, that is true, if you look at the physical parts of the mic. All those other types are for another day, but take my word for it, they are all either a dynamic or condenser mic.

Dynamic Microphones

The original mic was a dynamic mic. It is a very simple machine with just 3 basic pieces.
The diaphragm is usually flexible metal that is connected to a magnet that is free to move inside a coil of wire. Sound moves the diaphragm, the diaphragm moves the magnet and the movement of the magnet creates an electric signal in the coil that can be amplified.

Dynamic mics are pretty tough little things with very little inside to break, so they are used for heavy duty purposes and loud sounds. The louder the sound, the farther the magnet moves, and the stronger the signal is when it reaches the amplifier.

The bad part is the magnet. The bigger the magnet, the stronger the signal. Sounds good right? Yeah, but having that big magnet moving means that the mic can’t respond to the little changes that give that crispness and special qualities that show the differences in fine instruments and vocals.

Pros:

• Tough, heavy duty microphone
• Can handle loud sounds
• Doesn’t require outside power

Cons:

• Not as responsive

Condenser Microphones

Given the limitations of the dynamic mic we needed something that did not have those limitations if we wanted to hear the subtle harmonics in a concert grand piano and the breathy presence of your favorite soprano. So here is what we came up with.

We have a diaphragm like in the dynamic mic, but it is much lighter. It is suspended above a back plate that does not move. Both of these pieces conduct electricity because the electrical signal that reaches the amplifier is changed as sound moves the diaphragm closer and farther away from the back plate. Notice that I said the electrical signal is changed by the diaphragm, not like the dynamic mic which creates a signal. The signal has to come from somewhere, so there is a battery to supply it.

The diaphragm doesn’t have to do the work of moving a big ‘ol magnet, so it can be VERY light and moves easily so it picks up much more complex sounds (it picks up the nuances and harmonics better). There is a drawback to all that lightness and ability to move easily. Loud sounds can ruin a condenser mic. Harsh handling can do the same thing, so you have to be more careful with condenser mic than dynamic mics.

For the electrical engineers in the audience, I know, this is a very simplified description of the electrical properties of the condenser mic, but remember I said we were avoiding all that junk. Knowing that the condenser microphones are actually capacitors does not help us understand how to use microphones, so we aren’t going there.

Pros:

• Very responsive

Cons:

• Requires power
• Easier to damage
• Can’t handle loud sounds

So there you go. Every mic you see is either dynamic or condenser no matter what they look like. How can you tell? Well, you can’t always just by looking. Checking for a battery isn’t foolproof, because power can be supplied from another source like a mixer. A wireless mic has a battery, but that doesn’t necessarily mean it uses the battery for the actual microphone. We will revisit this problem later in the series, so don’t worry, you will be able to figure it out pretty quickly when we are done.

Next week we will look at pickup patterns and frequency response curves. Don’t worry, it will be fun!