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Microphones
Microphones are electronic tools that translate sound waves into signal. In the music business, we use microphones for audio recording and stage performance.
Some microphones are built for specific tasks, and some can function as multipurpose devices that have
a place in the recording studio, as well as in live performance. Within both categories, there are many mic
types to choose from. So how do you begin to understand which ones to use? To know which mic fits the task, there
are a number of factors to consider. The type of instrument, room acoustics, desired characteristics, number of
sources, intended texture for the recording, among others. Now most of these factors will not be worked into your
production habits until you have a fairly large microphone selection, and by then you should already know which will
be best for what. However, you obviously should have fundamental knowledge and experience with microphones. While you
must do your research using and experimenting for yourself, I will outline the details of what you should know when
using microphones in the recording studio or on the stage. There are three main points i will explain, which will
lead to successful audio recording for anyone with the means. (i.e. equipment, time)
1) What is a microphone, and how do they work?
2) You must understand which type of microphone will best suit the source you are recording.
(Specific knowledge on the categories of microphones and their differences will improve your recordings.)
3) The last, but most important point to understand is:
Supplementing your knowledge on how microphones work, with effective microphone placement techniques,
will give your audio recordings the best chance to become outstanding tracks in a song.
What is a Microphone?
A microphone is the first source in the audio signal path. A microphone is a transducer, or a mechanism that
changes an energy source from one form into another.
Why are they important in a Recording Studio?
Being the initial device in the audio signal path, a quality microphone is an important piece of the puzzle.
If the microphone is cheap, distorts the signal, or adds other negative characteristics, then the recording will be inherently flawed from the beginning. A decent quality microphone, typically 100-300 dollar range is
recommended.
What Does a Microphone Do?
When dealing with analog audio, a microphone changes sound waves into an electrical signal.
Microphones receive and transmit signals in several different ways. While each method
varies in design, all transducer microphones turn audio vibrations(sound) into voltage amounts.
Categories of Microphones (Transducers) Used for Recording or Performance:
Condenser: A condenser mic is a capacitor microphone that uses a conductive threshold (a.k.a diaphragm) which is set in front of a metal back-plate. Both pieces are charged with static electricity. When sound waves touch the threshold, (diaphragm) it vibrates and transmits an electrical signal representative of the audio.
*It is important to know that condenser microphones require phantom power to operate. Ribbon and dynamic microphones do not.
Dynamic: The dynamic microphone capsule uses a coil of wire; which is suspended in a magnetic field. The coil is disrupted by sonic vibrations, which generate an electrical signal.
Ribbon: A very thin (wafer-like) piece of metal foil, also known as a ribbon, is suspended in a magnetic field. When sound waves hit the ribbon, the vibrations send an electrical signal to it's next audio
source.
*This is a semi-technical explanation that may be useful to some, but, the technology of each piece in a mic
capsule is not critical to fully understand as of yet. However, the definitions below are important to know. These definitions cover the characteristics of these microphones and some of the ways they can be used.
Condenser Microphone
Ribbon Microphone
Dynamic Microphone
Polar Patterns
Microphones are also built to receive sound in different ways. Specifically, microphones are designed to be more
or less receptive to audio coming from a defined direction.
I) Uni-Directional Microphones: Are most receptive to the sounds coming from a single direction, in front of the mic. These microphones are good for isolation, and do not pick up a lot of room acoustics.
Patterns of the (One) Unidirectional Microphone
1) Cardioid - Picks up a wide range of sound in front of the mic.
2) Super-cardioid - Less receptive to sounds from areas other than a (more) narrowed portion in front of the mic.
3) Hyper-cardioid - Offers the most rejection from the sides, available in a undi-directional microphone.
II) Bi-Directional Microphones: Receive sound waves from two directions. Directly in front of and behind the
mic. Rejects sounds from the sides of the mic. Good for recording
conversations and duets, etc.
III) Omni-Directional Microphones: Receive sounds from all directions. Picks up most room acoustics.
Less sensitive to bass boost, pops, etc. Good for overhead mic'ing, recording
jazz ensembles, symphonies, etc.
*The types of microphones we have just reviewed, explains the encyclopedic definitions of their design & functions.
In audio recording nothing is written in stone. Again, the best way to learn what sounds good to you is to experiment
on your own.
Microphone Placement and Recording Techniques
To avoid recording noises from an unwanted source, (i.e. room acoustics, processors, etc.) a unidirectional
microphone can be used to isolate the sound waves of a desired source. Remember that the closer you place the microphone
to the source, the louder it will sound.
Use pop filters. Pop filters will smooth the audio being received by the microphone. It will help reduce popping sounds and
sizzling S's that frequently occur during vocal recording. Pop filters with metal screens have done this better in my
experience than cloth screens.
Walls reflect sound waves. Microphones directly facing flat surfaces often pick up unwanted reverberations.
The 3 - 1 Rule should be applied when recording instruments in the same room silmiltaneously.
Take care of your mic cables. Broken or damaged cables can lead to signal disturbance in a recording.
Foam can be applied to walls for treating the acoustics in a room. Despite what you may have seen in movies, do not
use your saved supply of McDonald's egg cartons on the wall assuming they will treat the walls.
Good Luck,
James
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