Pro Audio: Microphones 101

Pro Audio with Josh Sularski

In my previous Pro Audio Series articles, we covered some of the basics in putting together your first home studio. We walked through the fundamentals of selecting a computer, audio interface, and software. This brings us to the world of microphones. In this article, we will review the two most common types of microphones, how they work (yay physics?), and how you might decide when to use each type. By understanding the differences between microphone types, you will be better suited to fully understand my next article where I will make specific microphone recommendations for various vocal and instrument sources.

Dynamic vs Condenser Microphones

When shopping for gear, you’ll find two types of microphones that dominate the market: dynamic microphones and condenser microphones. While they often look similar, there are important differences you should understand so you can select the microphone that is best for your needs.

Dynamic and condenser microphones capture and convert sound waves in different ways. The mechanism that converts sound waves into audio signals is called a transducer, and each microphone type has a unique transducer for accomplishing this.

Dynamic Microphones

Picture of a Shure SM58 dynamic microphone in a mic stand on a purple background.

Also known as a “moving-coil” microphone, dynamic microphones convert sound waves using a combination of a magnetic transducer1, diaphragm, and coil. It’s a remarkably simple design; sound hits the diaphragm causing the coil to vibrate and “disturb” the magnetic field of the transducer. As the coil interacts with the magnetic field of the transducer, currents are created which travel out of the microphone, through a microphone cable, and ultimately make their way to a preamp on your audio interface.

Due to the moving-coil mechanism that dynamic microphones use, they are typically less sensitive compared to their condenser microphone counterparts. They are also considerably less sensitive in picking up higher frequencies and transients2, though they generally have great rejection from the rear.

Dynamic microphones are great for live applications or in any scenario where durability is paramount (I’m looking at you, studio drummers). You’ll find them in most live rigs, and used on snare drums and toms in the studio thanks to their ability to take an occasional accidental beating. They are also typically less expensive than condenser microphones since their designs are so simple.

Dynamic Microphones at a Glance

Pros

  • Rugged, durable, and reliable
  • Simple design
  • Good rejection from the rear
  • Often more affordable
  • Great for live sound

Cons

  • Less sensitive to higher frequencies and transients
  • Not great at picking up distant sounds

Condenser Microphones

Picture of a black condenser microphone in front of a computer screen

Condenser microphones, also called “electrostatic” or “capacitor” microphones, convert sound waves into audio signals through a more complex design compared to dynamic microphones. Condenser microphones use a combination of two plates to form a capacitor3. The two plates consist of a stationary back plate and an exceptionally thin front plate. As sound hits the front plate, it physically moves it closer to the back plate, generating a change in the capacitance. However, on its own, this sequence of events is not enough to generate an audio signal out of the microphone.

In order for the capacitor to detect these changes in capacitance and convert sound waves into an audio signal, the condenser microphone (and therefore the capacitor) must receive power from an external source. This power source is often referred to as “phantom power” or “+48v”. Without providing power to a condenser microphone, you will never capture an audio signal no matter how much you turn up the microphone pre4. The good news is that just about any audio interface with mic pres you buy will have the ability to provide phantom power. Still with me? Good!

Compared to dynamic microphones, condenser microphones offer a broader frequency response and are especially well suited for capturing high frequencies. They also offer better sensitivity to transient sounds, and as a result, are often the first choice for recording vocals and instruments in a studio environment. Simply put, condenser microphones capture more nuances compared to dynamic microphones.

As you might have guessed, the internal design of a typical condenser microphone is more complex than a dynamic microphone. Between the two-plate capacitor mechanism and the additional internal electronics (with +48v running through them!), condensers won’t hold up as well under abuse like a rugged dynamic microphone.

When price shopping condenser microphones, you’ll find a rather big divide between low-end and high-end models. Expect to pay anywhere from $50 for an entry-level microphone, to $5,000 or more for some of the world’s most coveted microphones. Hey, we can dream, can’t we? And while you’ll benefit from better component quality as you step up in price, there’s arguably a point at which you get a diminishing return on your investment. At what price that happens will forever be a contentious debate on many pro audio discussion threads.

Condenser Microphones at a Glance

Pros

  • Offers a wider frequency response, especially higher frequencies
  • Great sensitivity to transient sound
  • Captures more detail in a vocal or instrumental performance
  • Entry-level and mid-range models can be greatly improved with DIY mods

Cons

  • Usually more expensive than dynamic microphones
  • Not as rugged, not as common in live rigs
  • Requires phantom power

So which microphone type is best?

Unfortunately, there is no easy answer here. It simply depends on your application.

Gigging with your band on the road or running live sound at your church? You’ll probably seriously consider a rugged, dynamic microphone like a Shure SM-57 or SM-58.

Recording vocals and guitar in your home studio? A condenser may provide you with the better frequency response and detail you desire so you can capture the perfect take in all its glory.

But as usual, there are no hard rules here. Some of the most famous vocal performances of all time have been recorded on a Shure SM7, a dynamic microphone.

Next time we’ll review some popular microphones for specific sources including male and female vocals, drums, guitars, piano, and more. And, I’ll make some recommendations for your first microphone purchase if you’re just starting out on a budget.

Previous Pro Audio Articles:

Notes:
1 a transducer converts acoustic energy into electrical energy
2 a transient is a high amplitude (i.e. loud), short-duration sound, typically at the beginning of a waveform
3 a capacitor stores electrical energy in an electric field. Capacitance is the ability of an object to hold an electrical charge.
4 a microphone pre or preamplifier increases a microphone’s signal to line level so that it can be processed by audio equipment like a mixing console or recording device. Without a microphone preamplifier, microphone signals are too weak for processing by other equipment.



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  • One of the advantages of a condenser mic, if you are an amateur running a powered sound board with non-amped speakers, is that if you want to quickly turn the microphone on or off to allow for soloists, all you have to do is toggle the mic/line switch. When the switch is in “line” mode, there is not enough power to send the signal through to the speakers.




  • The article says “Condenser microphones use a combination of two plates and a metal diaphragm to form a capacitor3” but then no further mention is made of the metal diaphragm. Only discusses the 2 plates.
    What is up with the diaphragm?




    • F Public, I apologize. That is my fault as the result of a bad edit during my proofreading of the article! The front plate is actually often referred to as the diaphragm in question. And the back plate is the second, stationary plate. As that front plate moves in relation to the stationary backplate, that is how the change in capacitance happens to generate an electrical signal from sound source. I am updating the article right now! Thanks for catching my error.