Originally I was planning to dive right into microphones for your home studio. I was going to make a few recommendations based on what you are recording, and that was it. It would still be great information. I plan to still do this in the next blog post I’ve even started outlining the article then I thought ” why not go into a little more depth about microphones”. Almost like a microphone crash course covering everything from “polar patterns” to “condenser microphones” and everything in-between.
This article will cover the basic concepts of a microphone the next post ”The Best microphones for Home Recording Part 2″ will cover specific recommendations based on budget and need, along with a lot more.
Types of Microphones
There are 3 primary types of microphones which are condenser, dynamic, and ribbon microphones. They each have their pros and cons and each work differently which we will cover.
Condenser microphones need a power source which is normally static electricity thus it needs an additional power source which is known as phantom power. Phantom power is typically 48 volts. Condenser microphones are a big capacitor with one of the plates moving in responds to the sound wave that it is picking up.
They typically are more sensitive and can not handle as much volume with out distorting or other wise known as “SPL” (sound pressure level). Also, their frequency responds tend to be a little flatter however this is not always the case.
I should also mention that there are also small diaphragm and large diaphragm microphones. A small diaphragm is simply that it has a smaller diaphragm. Small diaphragm microphones general are used to isolate a given area and a sensitive. Where its bigger brother large diaphragm microphones can not keep up.
A great use of a small diaphragm microphone would be on an acoustic guitar or string instrument. A great use of a large diaphragm microphone would be for vocals.
Dynamic microphones differ from condenser microphones in that they do not use electricity they use magnets, diaphragms and coils. Simply a diaphragm is connected to a coil, when a sound wave hits the diaphragm it moves back and forth across the magnet which creates current in the coil and is then sent down the microphones wire to the xlr cable and on to the audio interface. If you are a visual learner this diagram will help make this simple and easy to understand.
Ribbon Microphones are a form a dynamic microphone, but they differ in two main ways first the coil is made a thin strip of metallic foil instead of a typical coil. Another difference is that they receive sound from the front and back where the dynamic microphone normally only is able to receive sound from one direction. If you would like to read more about the history of ribbon microphones click here.
Microphone Polar Patterns
So what is a polar pattern? A polar pattern is “The Graphic representation of the sensitivity of a microphone over all incident angles at a rated frequency”. This is very important to know as it will change which microphone you will use and how it will be placed.
For example, If you are recording vocals you will want a microphone that is more direct and is one-sided to avoid picking up reflections, which makes a cardioid polar patter is a desired polar pattern.
If you wanted to record room noise for drums or a group of singers at once you could be an,Omni polar pattern. There are good uses for every polar pattern however at least in my case I use cardioid and Omni polar patterns the most.
Here is a definition of each polar pattern
Omnidirectional Microphone Polar pattern - A microphone with a polar pattern that is equally sensitive to signals arriving from all angles .
Directional Microphone – A pressure gradient microphone that is sensitive to sounds arriving from set directions
Cardioid Polar pattern – A polar pattern that is sensitive to those signals arriving from the front and rejects signals arriving from 180 degrees off-axis
Super cardioid polar pattern - A polar pattern that is sensitive to those signals arriving from the front and rejects signals arriving from 125 degrees off-axis
Hyper Cardioid Polar pattern – A polar pattern that is sensitive to those signals arriving from the front and rejects signals arriving from 110 degrees off-axis
Bi Directional or figure 8 Polar Pattern – A pure pressure – gradient microphone designed to accept signals arriving from in front (0 degrees) and rear (180 degrees) of the diaphragm and to reject signals arriving at +or-90 degrees off axis
Microphone Frequency Responds, Roll Offs, and Pads.
All Microphones have their own way they respond to a frequency which is called frequency responds. The photo above shows a Shure SM57 frequency responds it shows how well the microphone responds to a given frequency. This is is part of what gives each mic it’s flavor or unique sound. As you can start to see a lot goes into deciding on what microphone to use while recording including pads and roll offs.
A roll off is a gradual, continuous decrease in low-frequency response. Depending on what is being recorded it may be ideal to roll off the low end so less of it is recorded. An example of this would vocals as they are in the mid range you may not want all the low end while recording to avoid proximity effect.
A pad is something that can reduce the input level before it gets to the pre amp. This is particularly useful if you have something that is very loud or has a high spl (sound pressure level) that is clipping or distorting while you are trying to record. If the microphone has it a pad can be engaged and the level will be reduced, and hopefully your signal is no longer clipping.
Please keep in mind this is a very basic guide if you would like to go more in-depth check out this wiki.
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