Microphones 101:


A Review of the Basics
Print this article

In the first several issues of Shure Notes, we were rarely able to sidestep basic discussions about microphone construction and characteristics. And while our editorial journey (see Read All About It to review and download past issues) has taken us along a path that has included topics as diverse as podcasting, home recording and careers opportunities in the music industry, there are still issues where we need to return to the basics. This is one of them.

The rules are yours to develop and your solutions will be unique to the audio challenge you're facing or the sound you want to achieve. (After all, that's what this issue is all about.) If you've been a longtime reader of Shure Notes, or you have a good grasp of the basics, pass “GO” and proceed directly to the Pros feature. You've paid your dues. But if you think you can benefit from some general guidelines, you may want to consider the following.
Most manufacturers produce microphones for specific types of sound sources. Microphones that are specifically designed for drum kits have different characteristics, for instance, than those that are used for vocals. Are you miking your acoustic guitar? Or your guitar amp? Are you recording a rap in your home studio? Or are you looking to rock the house with screaming vocals? In most, but not all cases, your first choice will be between a vocal mic and an instrument mic.
Here's where we need to spend a little time on what microphones do and how they work.

What They Do: A microphone is a device that changes sound into an electrical signal.

How They Do It: Inside the microphone are transducers. The two most common types are:

Dynamic
 A simple, rugged diaphragm/coil. It handles extreme volume levels without distortion.

Condenser
A lightweight, sensitive diaphragm that precisely and smoothly captures sound nuances. It is powered by battery or phantom power supply.

The chart below gives you a broad overview of some of the characteristics of dynamic and condenser mics. Please note, these are very general guidelines – there are exceptions in most categories.

Construction
Simpler
More complex

Cost


Less Expensive
More expensive

Handling
Tolerates rough handling
Requires more careful handling

Sound Quality
Excellent over a wide frequency range
Very sensitive, smooth natural sound even at high frequencies

Power Source
Does not require a separate power source
Requires batteries or phantom power

Miniature Version?
NO
YES, because pre-amp circuitry can be housed in separate unit

Environment
Good for live performance
Good for controlled environments and recording

Shure Mic Example  
SM58® (vocal) and SM57 (instrument)
Beta 87A™ (vocal) Beta 98/S (instrument)
Fundamentals of Frequency Response
Every microphone has a signature and part of that signature is its Frequency Response. Frequency Response determines the basic “sound” of the microphone. It is determined by the range of the sound (from lowest to highest frequency) that a microphone can reproduce and how that sound varies at different frequencies.

The most common response curves you are likely to see are flat and tailored. When you look through catalogs or web pages, you're probably going to see icons that look something like these.
This section of Shure Notes uses Macromedia Flash.

If you cannot see the movie, you may download the Flash plugin here or simply click below to view the alternate PDF version.

Portable Church Industries Recommendations
Whether you think of it as directionality or a microphone's polar pattern, there are two basic types you need to consider – omnidirectional (all directions) and unidirectional (one direction).

This is the symbol associated with an omnidirectional mic. It can't be aimed to isolate one area.

Best to use for: Choral groups, orchestra and other large sound sources.
This is the symbol most often associated with unidirectional microphones. These are sensitive to sound coming from only one direction. The most common type of unidirectional microphone is called a “cardioid” because its pickup pattern is heart-shaped. It picks up most sound from the front of the microphone and some from the sides. Supercardioid or hypercardioid microphones offer even greater sound distinction through narrower pickup patterns.

Best to use for: Live sound, since these mics isolate sound from one voice or instrument and can be aimed away from loudspeakers to avoid feedback. That's why unidirectional microphones far outnumber omnidirectional microphones.

You can find time-tested techniques for miking live or recorded vocals and instruments – for FREE – in past issues of Shure Notes: Rock Solid Live Sound Basics and Making an Independent Recording, Part II. Also, for a more comprehensive discussion, check out Shure's Mic Techniques for Studio Recording and Mic Techniques for Live Sound Reinforcement, available as PDF downloads or in print form by clicking here.