Recording 101: Microphones
Updated: Nov 26, 2019
Microphones are the start of the recording chain and can make a major difference in how your recordings sound! There are so many to choose from for any budget that it can be intimidating, but my goal for this blog is to demystify the microphone jargon, explain the different types of microphones, and suggest uses for each type.
Let's get all the technical information out of the way first!
The images above will either put you to sleep or freak you out but it is actually very easy to navigate and can help you figure out what mic is best for your sound source!
The diagram tells us that this mic does not respond to frequencies lower than about 45Hz. There is a low shelf until 200Hz, a slight dip at 400Hz, then an increase starting at 2000Hz until 6000Hz. There are bumps above 6000Hz, and eventually rolls off around 12000Hz.
What does this mean? This means that this mic is well suited for sound sources that fall within the mid and upper mid range of the frequency spectrum. The Shure SM57 is a very popular mic because of the way it accurately captures the mid range and adds to the upper mid range. If you have ever mic'd up an instrument, chances are it was the 57.
This diagram tells us how the microphone responds to sound based on how it's pointed at the source. For example, if we look at the diagram above for the Shure SM57, we see that if you point the mic at a 90 degree angle from the source, it will respond -5dB at 125, 500, 1000, and 2000Hz. However, we see the response fall to -10dB for 4000 and 8000Hz.
What does this mean? This means that at a 90 degree angle, the mic responds as if there is an EQ that lowers the high end of the source. This is good to know because if you are recording an acoustic guitar, you'll want to have those higher frequencies in your recording. With this information, you can angle the mic in a way that allows for the best EQ response.
There are several different types of polar patterns: Cardioid, Supercardioid, Hypercardioid, Bidirectional (figure 8), and Omnidirectional. Check out the image below to see how these different polar patterns pick up the audio source from different angles.
There are other specifications that a mic will include, but for our purposes these 2 diagrams will be more than enough information.
Ok - now we know how to read the charts that are included with the microphones. Let's talk about the different types of microphones.
1. Dynamic Microphones.
A dynamic mic captures sound through movement of the capsule. When a sound wave hits the capsule, it moves a coil and creates an electrical current. The benefits of this type of mic is that it is very dependable and can take a beating. These mics also tend to have a similar frequency response - namely shelves at the lower and higher end of the frequency spectrum as well as bumps in the mid and upper mid range. The downfall of these mics is that they lack some of the detail in the upper mids and high end range that a listener would hear as sparkle, shimmer, or air.
2. Ribbon Microphones.
Ribbon mics are another branch of dynamic microphones but they work in a different way. Instead of a coil, they are built with a thin magnetized ribbon that moves sympathetically with the audio source. They are associated with a warm low and midrange with a roll off at the higher frequencies. These microphones are very fragile! Dropping these mics or even an extremely loud audio source can break the ribbon. In addition, the conversion from audio to electricity is very low and these mics require high end or specialized mic preamps.
3. Condenser Microphones.
Condenser mics work by utilizing an electrical element called a capacitor. The diaphragm is placed between two capacitors and in front of a back plate. The motion of the audio source hitting the diaphragm is converted to electrical current. These microphones are known for their accurate representation of the audio source and the detail and nuance they are able to capture. They are very sensitive and can pick up unwanted background noise. These microphones need Phantom Power, which is what charges the capsule. Most preamps and interfaces have phantom power available (often noted as +48dB).
There are three main types of condenser mics: Large Diaphragm, Small Diaphragm, and Tube Condenser mics. The size of the diaphragm is what separates the large and small while the tube condenser is powered through a special tube preamp.
Now that we know more about the different microphones, which ones do we use?
There is a general consensus that dynamic microphones are better for drums, ribbons for guitars, and condensers for vocals. However, rules are always made to be broken! For example, Michael Jackson recorded all his vocals using a dynamic mic for the album Thriller! and most engineers will use a combination of dynamic and condenser microphones on a drum kit. Each type of microphones has strengths and weaknesses, so here's some things to consider when looking for a microphone:
1. Condenser microphones have a beautiful top end when recording vocals, but dynamic mics are better at reducing or rejecting background noise.
2. Ribbon mics have a warm and lush quality but are brittle and require a higher quality preamp.
3. Dynamic mics are rugged but may not capture the detail you hope or expect on an acoustic guitar compared to a small or large diaphragm condenser.