Microphones, Part 1: A Guide to Dynamic Mics

In part 1/2 in this guide to microphones, Matt Loel T Hepworth examines the ins and outs of dynamic microphones and what recording tasks they are best suited for.  

It cannot be overstated: Microphones are the most important components of any recording studio. Unless your musical productions are of completely electronic origin, you'll need microphones to capture the organic components like vocals, acoustic instruments, and the instrument amplifiers of corporeal (usually human) performers. Microphones are the ears of your studio; the sound waves they capture will be converted by your DAW into ones and zeros, and only when the finished product is played back will the air molecules bounce around to communicate the intent of the music to the end-listener. Do it right and the intent is easily understood. Do it wrong and the listener might end up confused, or even worse, disinterested. Therefore, choosing the right mic for each task is critical.

One of the most wonderful aspects of microphones is that they rarely become obsolete. You can use them over and over again and they'll consistently capture sound based on their design specifications. You'll get decades of use out of them. In fact, your mics might even provide you with generations of use. I still use a pair of my dad's very unique AKG D200E microphones, and they sound as good today as they did back in 1978. So unless you simply don't like a mic or no longer have a use for it, you'll rarely need to sell it, and the longer you keep it, the more value it will provide.

There are a staggering number of high-quality and very affordable microphones on the market today, which makes choosing one a somewhat daunting task. However, I'm going to give you a little knowledge to help you easily find mics that fit your budget as well as the task for which it will be used. In this article, I'll be providing you with examples of four popular microphones and compare them by (in no particular order) the following criteria:

  • Frequency Response (measured in Hz units)
  • Polar Pattern (a geometric measure of directionality)
  • Sensitivity (measured in dBV {decibel Volts})
  • Maximum Input Sound Pressure Level (SPL in dB, for condenser microphones only)
  • Street Price (measured in the hurt it puts on your wallet)

Dynamic Microphones

Dynamic microphones are of very elementary design. Basically, a thin membrane (the diaphragm) is vibrated by sound waves. The membrane is attached to a small coil surrounded by a magnet. The small electro-magnet current generated by the vibrating membrane is then sent out of the microphone, down the mic cable, and into the microphone preamp of an audio interface or mixing console. Dynamic mics have very few electronic components, which tend to make them more affordable, durable, and reliable. (Note: Ribbon microphones are a more esoteric variety of dynamic microphones.)

But the most significant benefit of a dynamic mic is its ability to capture loud sounds without risk of distortion. The sparse compliment of internal electronics means there's nothing to overload, which is why they're often used on drums and loud instrument amplifiers. Perhaps the most ubiquitous example of a dynamic microphone is the Shure SM57.

Figure 1. The Shure SM57 mounted in an On Stage MY420 shock mount.

Figure 1. The Shure SM57 mounted in an On Stage MY420 shock mount.

Released in 1965, the SM57 is one of the most venerable and popular microphones in history. It's a microphone that sounds good recording practically anything, and sounds great recording many specific things. Snare drum, electric guitar amplifier, trumpet, and alto sax would be well-served by the SM57.

Now let's look at the specs:

  • Frequency Response: 40 Hz to 15 kHz
  • Polar Pattern: Cardioid
  • Sensitivity: -56.0 dB Volts
  • Maximum Input SPL: n/a
  • Street Price: $99.00

Human beings are capable of detecting sounds in the 20Hz to 20kHz range, so the SM57 can't capture all the frequencies to which humans are sensitive. However, frequency response is not completely representative of a microphones sonic character. The cardioid polar pattern means you have to point the mic directly at what you want it to '

Matthew Loel T. Hepworth

More articles by this author

MATTHEW LOEL T. HEPWORTH has been teaching music technology since 1984. The son of educators, he has the ability to thoughtfully instruct people to get the most from complicated music products and software. He authors the Cubase and WaveLab tutorials for macProVideo.com and authored several books including WaveLab 7 Power!, The Power i... Read More

Discussion

Peter Schwartz
FanTAStic article. Learned things about these mics that have totally escaped me despite my many years in this business of making music. I hope Matt and Rounik will conspire to allow for additional articles on mics that go into exactly the same kind of detail.
Peter Schwartz
Ah, I see this is just Part 1. Yay. Can't wait for more!

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