An introduction to mic types and how they work

Published by | Tuesday, October 30th, 2012

Have you ever wondered how dynamic, ribbon, and condenser mics vary in function, price, and utility? Or how a mic picks up sound, and how that mic’s pickup pattern might affect its placement in the recording process? In this blog post, I will explore these questions offering visual examples from our recently released Audio course, Audio Recording Techniques.

How dynamic, ribbon, and condenser mics differ

Microphone technology is fascinating. A dynamic mic utilizes a metallic diaphragm that moves a thin coil of wire wrapped around a magnet to convert acoustical energy into electrical energy. In contrast, a ribbon mic uses a very thin strip of aluminum foil as a diaphragm, which enables it to move quickly in reaction to acoustic sound, yielding great high-frequency response. Condenser mics utilize a different setup. They have two electrically charged plates, one that moves as the diaphragm and one that’s fixed. This design allows for the mic to respond well to very dynamic audio signals.

Check out this video from Chapter 2 of Audio Recording Techniques to see the inner workings of dynamic, ribbon, and condenser mics, and to learn more about their characteristics and applications:

How microphones pick up sound

Microphones receive sound either directionally (from one direction only), omnidirectionally (from all directions at once), or somewhere in between. The way a mic receives sound is called the pickup pattern, and four patterns are typically found in mic design: omnidirectional, cardioid, hypercardioid, and figure 8. A cardioid pickup pattern is heart-shaped and enables a mic to pick up audio signals directionally. Thus, when you point a cardioid mic at a sound source, the mic will pick up the sound from the direction of that source, but will not pick up nearly as much sound from sources coming from other directions. Hypercardioid patterns are even more focused and directional than cardioid patterns, and mics with figure 8 pickup patterns record sound from the front and back sides of the mic, but don’t pick up anything on the sides (hence the pattern name figure 8). In contrast, mics with omnidirectional patterns pick up sound equally from all directions at once.

Regardless of the pickup pattern, a mic doesn’t actually pick up frequencies in the exact same pattern. For example, a Shure SM58 dynamic mic picks up lower frequencies in more of an omnidirectional pattern, while picking up higher frequencies in a hypercardioid pattern. In microphone manuals, pickup patterns at different frequencies are often shown as confusing 2D diagrams. Interpreting these diagrams is a frustrating challenge because they’re really meant to show 3D shapes. We took this conundrum into account and added 3D renderings of omnidirectional, cardioid, hypercardioid, and figure 8 pickup patterns to Chapter 2 of our Audio Recording Techniques course:

Audio Recording Techniques  goes way beyond the microphone and recording basics. Follow author Bobby Owsinski as he walks through the recording process of an entire song (Simply Falling by the artist Iyeoka) with A-list session musicians in a top-of-the-line studio. Plus, check out the course to learn about recording techniques for all types of instruments, including drums, guitars, keyboards, bass, strings, horns, and vocals, and to see more 360-degree, 3D visualizations, which provide a unique perspective on recording equipment, players, and mic placements.

 

Interested in more?
• All audio courses on lynda.com
• All courses by Bobby Owsinski on lynda.com

Suggested courses to watch next:
Audio Mixing Bootcamp
Foundations of Audio: Compression and Dynamic Processing
Music Editing for TV and Film in Pro Tools
Digital Audio Principles 

 

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