Saturday, July 4, 2009

Explaining microphone types, part two.

Knowing the different types of microphones can save you time when recording, and allow for a better quality of recordings.

In part one (of this three part post) we discussed the three most common types of microphone designs. In this post, part two, I want to dial in more closely on the polar patterns of microphones.

To begin I feel it is important to know what the microphones can actualy hear, or often times more importantly; what they can’t hear. This is what we sometimes call the polar pattern of a microphone. The term “polar pattern" speaks about the direction (outward from the microphone itself) that a microphone can hear.

The most common polar patterns are cardioid, hyper cardioid, omni, and figure eight.

But what do these microphone terms mean, and how can knowing these terms help in your recordings? What is this information good for? Well, knowing what you do not want to record is just as valuable as knowing what you do want to record.

“Bleed” is what we call any unwanted noise that enters a microphone from an unwanted direction. Perhaps it is as simple as a snare microphone picking up “bleed” from the guitar amp that is off in the distance. When the microphone is solo'd, the guitar amp can be heard along with the snare through the snares' microphone. This can muddy up a session.

We can control “bleed” by choosing a microphone that ignores, or rejects noise coming from certain directions. Enter into polar patterns of microphones.

Well, let’s start off this quick explanation with the cardioid polar pattern microphone. To be more specific, it details the width of an area that the microphone can hear. A cardioid microphones’ “hearing”, or polar pattern looks like the image below. Yea, it is crude, but it works.

Sound enters the cardioid microphone easiest from the front, less from the sides, and not at all from the rear. The ring arround the microphone in the image above shows this directional concept.

As you can see sound enters the cardioid microphone from quite a narrow range of direction. However, the distance that a cardioid microphone can “hear” is not as narrow as a “hyper cardioid” microphone, which is very limited. Bleed is more controled, or defeated much more with a hyper cardioid microphone.

But what if you need to pick up a sound source that is in a 360 degree space? An “omni” directional microphone hears in all directions, and can handle some amazing reverb like effects, and some very cool sounds! You can see the “omni” polar pattern in the image below…

You can see how a Hyper Cardioid microphone might come in handy for picking up just one piece of a drum kit and not allow any sound (bleed) from the other pieces of the drum kit to enter into the microphone. An omni polar pattern microphone might be great for picking up a 360 degree “room sound”, or a group of back up vocalists standing in a circle around the microphone.

A “Figure of eight” microphone polar pattern is named so due to its look on a diagram. See the diagram below to see what I mean. Sound enters these microphones from two directions, which are also at opposite directions. You can set one of these microphones up so that sound enters from the front and the rear, or at opposing sides. These microphones are great for picking up a rooms’ deflection of sound, creating a rooms' deflection, reverb, or delay effect.

Now that you are familiar with the polar patterns of certain microphones, you might still be asking “which polar pattern types of microphones should you purchase”?

Well, here is your chance to save some of your cash!
There are microphones out there that have polar pattern switching available on the microphones themselves! This allows for a wide range of recording applications from just one microphone. Microphones that are capeable of switching its polar pattern tend to be a little more expensive, and the cost increases as the number of switch-able patterns increases. However, purchasing a microphone with variable polar pattern switching might be cheaper than purchasing as many different types of microphones.

So what about this “Proxy effect” thing that we have all heard about? What are the “high and low pass roll off” functions, and what are they for? Do you need a popper stopper, wind screen, or isolation screen in order to get decent sounding recordings?

These are some great questions folks, and I will need to ask you to stand by and wait until the next post is posted. In that post I will try my best to answer all of these questions, and add some other great microphone facts and tips!

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