Purchasing a microphone can be daunting. Even inexpensive microphones cost hundreds of dollars, and high-end microphones cost thousands. On top of that, there are a lot of options on the market and each one is a little different than the next.
So how do we know what to pick? We want to pick a microphone that is going to best suit our source. If we’re recording upright bass we want something that has a really clear transient response, a tone curve that’s a bit more receptive to the low end, a fairly wide pickup pattern, low proximity effect, and either very little component saturation or something that puts a little grit into it, depending on what we want.
Now, that all might have sounded a bit overwhelming to you — but don’t worry.
We’re going to explain what all of those things mean in detail so you know exactly what to listen for in a microphone.
Let’s start with tone curve because it’s the most obvious characteristic. Some microphones have a very neutral tone like the Audio Technica 4033a. Some microphones are very dark, meaning the top end of the frequency spectrum is rolled off, such as the Coles 4038. Some microphones have an upper midrange push like the Manley Reference C.
Every mic has its own tone. Many strive for a flat response, as that yields the most accurate representation of the source, and others deliberately give a bit of love to certain frequency ranges because they’re intended for specific purposes. For example, the Earthworks QTC is used frequently in classical music to pick up the exact sound of the instruments, while the AKG D112 is used primarily on kick drums because its tone curve is strongly weighted to the low end.
Match your mic to the source and intentions, and know the sound of your source. If it’s a bright acoustic guitar, maybe the top end needs to be tamed a bit. Pick a mic that will match that formula. A Neumann U47 rolls off the top end and would be a great choice to get a bright acoustic guitar feeling full and lush by taming brighter tones and showing a little love to the low end.
People attribute clarity to tone curve, but a big piece of that puzzle is how receptive a microphone is to the transients of a sound. Transients are the attack part of a sound envelope. For example, the consonants in a vocal contain transients. The crack of a drum is a transient. The pluck of a string or the strum of a guitar are transients.
Sometimes we want fast transient responses; vocals, acoustic guitars, room mics, drum overheads and upright bass benefit from having defined attack tones. Sometimes we want something that rounds the transients out — like close mics on drums or overheads that are close to the kit. Transient response tends to go hand in hand with SPL ratings — usually, mics with fast transient responses don’t fair as well right up on loud sources while slower mics tend to do well with high SPLs. For example, the JZ Black Hole is a perfect vocal mic when placed six to twelve inches from the singer, but an Electro-Voice RE20 might be better if the vocalist is going to press right up on the mic and belt out super loudly.
As a general rule of thumb, the heavier the capsule, the slower the transient response. Large diaphragm dynamic mics tend to be the slowest while small diaphragm condensers and ribbons are generally fastest.
Pickup pattern is nice and straightforward. This feature describes where the sound is picked up and where the sound is rejected. For example, an omnidirectional microphone picks up sound from all directions. A cardioid pickup grabs sound in front of the mic and rejects sound from behind and above. A figure-8 pickup grabs sound from directly in front and behind, but rejects sound from the sides, above and below.
The only consideration is that not all pickup patterns share the same breadth. Some cardioid mics have a fairly wide pickup acting almost like a half omnidirectional (cardioid small-diaphragm condensers tend to have this type of pickup), whereas some cardioid pickups are so narrow they only catch sources that are directly aligned with the front of the capsule (this is called a hypercardioid pickup and is used mainly for capturing dialogue for on-location sound). Figure-8 mics tend to be pretty directional, but there are a few exceptions. The Royer 122 active ribbon microphone is a very wide figure-8 pickup and there are perhaps a few other examples but this is pretty rare.
For most sources, you can’t really go wrong with cardioid pickups. If you want to grab more of the room sound then omnidirectional mics are a good choice. Figure-8’s can be used for more advanced miking techniques like Mid-Side or Blumlein captures, or styles of capture where the mic is placed near the sound hole but purposefully tilted away to catch more of the textural elements of the instrument. The other place figure-8 mics sound really good is when the interaction of the source with the reflective boundary is appealing, like drum overheads in a cool sounding room, or piano with the lid removed when you want to capture some of the “air” of the space while still having the mic close to the sound hole.
Directional microphones exhibit something called proximity effect. As the microphone is placed closer to the source, more low end builds up in the capture. This can be a fantastic tool or terrible nuisance. The degree of proximity effect is based on the type of capsule and the means in which the air pressure is ported, with every mic build yielding slightly different results.
Ribbon mics tend to exhibit the most proximity effect, dynamic cardioid mics tend to have very little, and omnidirectional condensers have none at all. Proximity effect is not a good thing or a bad thing— it’s simply a thing. Used correctly it can be a great tool for adding weight to a sound in place of an EQ. Used incorrectly it can add a lot of mud and boominess that can be difficult to remove.
This is the most difficult category to ascertain because it involves a lot of subtlety and because the effect is dynamic. There’s a degree of subjectivity because the component saturation (or color) of the mic will change with amplitude and frequency. And because this is harmonic distribution rather than straight-out tone curve, it’s easier to think of saturation as the “personality” of the microphone.
When I think of the personality of a U47, I think of a “warm” or “thick” and almost “whooley” sound that shows love to the low range and has a “dustiness” to the top end. Contrast this with a JZ Black Hole which has an “open” and “clear” sound that captures things cleanly and has just a bit of “sparkle” in the top end. The harmonics of a U47 are very concentrated below the 400 Hz range and has what I ambiguously describe as an “orange-colored” tone in the upper-mids. A Neumann U87 has concentrated harmonics between 1-2 kHz which makes it sound very “assertive” and tends to pull sources toward the front of a mix, while the upper-mids are a bit “gritty”, and the top end (if well-maintained) is “round and shiny”. Telefunken ELA M251’s have a particularly unique and wonderful almost “smeary” texture (in a good way) in the broad top end. The JZ Black Hole has very evenly distributed harmonics throughout the frequency spectrum which are like the sonic equivalent of looking through the Fiji Ocean — it’s a beautiful sound that’s hard to quantify.
What I love about the color of a microphone is that it’s up to interpretation and I feel is best described using emotional language. And it’s in this aspect that picking microphones becomes more art than science. There’s simply a difference in emotion when using a U47 to record strings versus using an Earthworks QTC. And picking the right emotion for the song is how we make our art.
Hope this helps. Till next time, make some Real Muzic.