Understanding mic types and characteristics, as well as their applications, is critical for effective audio engineering. There’s no single type of mic that does every job well. Even within individual microphone styles, there is a wide range of sonic flavor and sound variation.
In this article, we’ll take a look at the different types of microphones, some popular models of each, and dig into the basic operating principles behind each type.
The most common types of microphones that you’re likely to hear about are Dynamic, Condenser, and Ribbon, however there are multiple ways of classifying mics that we’ll check out more in-depth later on in this article.
These can be extremely rugged microphones, which makes them ideal for live sound applications.
There’s a common joke in engineering circles that the venerable Shure SM57 microphone doesn’t even sound right until it’s been dropped a dozen times. The reality is that the sound remains unchanged after drop number 12.
These are built like tanks, as is the Shure SM58, the SM57’s vocal mic version, with the metal mesh ball head that is often what people envision when you say the word, “microphone.”
On the plus side, their robust construction generally makes dynamic mics safe for high sound pressure levels. If you have a guitarist with an amp set to Spinal Tap level 11, throwing a dynamic mic in front of the cabinet is usually a safe bet. While many other mic types can handle these loud volumes, some can’t. It’s rare, though, to encounter a dynamic mic that might be damaged by extremely heavy volume.
That durability has a negative flip side that creates limits to the workings of moving coils. The diaphragm of a moving coil mic is attached to that coil. Vibrations detected by the diaphragm move the coil within a magnetic field and sound is converted from acoustic to electrical energy using electromagnetic induction.
Compared to other designs, a moving coil is a slow-moving beast. It takes effort to move them, since they must overcome their own at-rest inertia.
What that means in sound terms is compression. A moving coil mic has a natural compression that can be sometimes useful, particularly with loud sounds, but at the expensive of transient response.
This inertial resistance keeps a moving coil design from capturing crisp detail at the start of a sound cycle. Imagine a cymbal, for example. The complex “ting” to “sizzle” sounds when it’s struck happen quickly. Since a moving coil takes a measurable amount of time to start moving, the way it captures the sound of the cymbal is colored by the motion of the coil.
Despite the limitations of moving coils, the sound captured from dynamic is still quite usable in live and recorded applications. The range of sounds is also quite broad, depending on the design of the mic in question. While often used on instruments, moving coil mics can be quite successfully used for vocals, and some models are staples of broadcast radios, giving a bass-emphasized “radio announcer” quality to some voices.
Essentially the same mic electronically, the SM57 has a barrel head, while the SM58 has a ball head, the classic vocalist mic with extra padding to reduce “P” pops and breath noise. Excellent general-purpose mics though usually not used for studio vocals.
A large moving coil mic, the RE-20 is often found in radio studios, a classic DJ mic that’s equally at home in a bass drum, in front of a loud guitar amp or pointing at the bell of a brass instrument. This is a very flattering microphone with a bass proximity response that beefs up the sound of many sources while still retaining clarity and brightness.
A different voice entirely than Shure’s SM57 and 58, the SM7 is also a popular broadcast mic. While its output won’t overwhelm you – it needs a hefty amount of gain from a preamp – the sound quality rivals some condenser mics, usually the gold-standard for studio vocals. The SM7 is the microphone chosen by Quincy Jones to record Michael Jackson’s voice on the record-setting Thriller album, so this mic has serious singer credibility.
Microphones using the capacitance principle to capture sound are, like ribbon mics, not held back by the mass of a moving coil.
This allows ultra fast response to changes in sound pressure and, depending on the mic design, can produce detailed and realistic reproduction or, in the case of large diaphragm condenser mics, a brilliant, larger-than-life presence that delivers the sound of thousands of number-one hits.
The diaphragm of a condenser mic faces sound vibrations head-on, reacting to the vibrations of sound waves that hit it, making for remarkable sensitivity in both sound detection and detail. Remember, there’s nothing like a moving coil impeding the diaphragm of a condenser, only empty space between it and the charged plate.
Condenser mics are further grouped into smaller categories, based on diaphragm size. Here we’ll dive a bit deeper into large diaphragm and small diaphragm condensers. You will also commonly see and hear these mics abbreviated as LDC and SDC, respectively.
The size of the diaphragm of a condenser mic often defines the form factor of the mic’s design, but it also contributes to the characteristics. Condenser mics come with small, medium and large diaphragm sizes, roughly ½-inch, ¾-inch and one inch, respectively, though these aren’t standard sizes.
Small diaphragm condensers often come in a simple, cylindrical shape commonly called pencil condensers. Though they look tiny, they can be giants when it comes to capturing sound. A stereo pair of quality pencil condensers may be all you need to make a superior quality recording of an orchestra, choir, or any other classical-style ensemble performing in an acoustically superior space. The detail and realism can be astounding, and the stereo image of the recording field has both depth and clarity.
Medium diaphragm condensers are in-betweenies. Some exhibit characteristics common to small diaphragm condensers, while others mimic their large diaphragm cousins. These, though, are a small segment of the condenser mic population.
Large diaphragm condenser mics are recognizable as “serious” studio microphones from many media and music video depictions. The reason for their video popularity is because they’re equally as popular for audio reasons.
These are the sparkly professional sounds microphones that give an effortless professional sheen to a sound source, such as a vocal or acoustic guitar. Sometimes they’re not, however, realistic. There’s an exaggeration over reality sometimes, additional sparkle or presence that isn’t part of the original sound. However, that exaggeration can be just the ticket, particularly in a multitrack ensemble recording.
If you’ve heard of phantom power, it may be in the context of condenser mics. Conventional condenser design requires 48 volts of direct current power that does nothing except charge the back plate to turn the condenser capsule into a capacitor. Most audio interfaces and mic preamps will come equipped with this feature and have a phantom power switch or button to toggle it on and off.
When plugging in a mic that requires phantom power, it is best practice to always turn the gain all the way down and disable phantom power before connecting the mic cable. Furthermore, you need to be careful when working with ribbon mics, because some models are wired in a way that the microphone could get damaged if phantom power is applied.
If there’s an internationally accepted “best mic,” the U 87 may be the one. This is a mic that gives nearly every sound source a fair hearing and reasonable representation. When perfectly matched to a voice, the results are transcendent. First introduced in 1967, it’s used everywhere in the studio, from lead vocals to cymbal overheads. To hear it is to know quality.
With a distinctive trapezoidal profile, the C414 is a multi-pattern large diaphragm condenser that rivals the U 87 as a Swiss Army mic. The current model, the C414 XLS has nine switchable polar patterns, so versatility is just everyday business for this mic. There are few applications it can’t handle with aplomb.
The U 87 and C414 are expensive mics, top-of-the-line professional tools. The great thing about the contemporary audio equipment market is, however, the amazing value that’s available, quality mics that might not rival the kings of the recording world, but which have musically valid voices and don’t require bank loans to purchase. The NT1-A is representative of the mid-level price point that’s heavy on audio quality. While the results may not be as sublime as a U 87 costing ten times more, the Rode is a very useful, talented mic. There are bargains to be had in the microphone world and here’s your proof.
The king of the pencil condensers, the KM184 has the goods to record a top-line grand piano, particularly in conjunction with… another KM184. Pencil condensers are frequently sold in pairs for stereo recording applications. It can often help to have electrically matched mics to capture beautiful instruments in a quality acoustical space, and the neutral coloration that small diaphragms deliver is, generally speaking, a terrific match. The KM184s are the Rolls Royce level for this application.
Also available in matched pairs, the sE8 represents about one-third the budget hit of the KM184s while providing most of the sublime detail. The sE8 shows again that reasonable price tags deliver superior audio in today’s market.
The diaphragm is just that: a ribbon. Suspended between the poles of powerful magnets, there’s no coil weighing down the ribbon’s response to acoustic vibration. Though ribbon mics and moving coil mics are both technically dynamic, they have dramatically different ways of working, so we will consider these separately.
Ribbon mics often have a smooth and natural sound. If you recognize the jellybean shape of old RCA mics from the 40s and 50s, you recognize the look of vintage ribbons. Singers such as Bing Crosby, Billie Holiday and Frank Sinatra were captured with ribbon mics back in the day, and these were the go-to studio vocal mics for years.
In addition to complimenting many vocalists, ribbon mics are fantastic at taming sounds which other microphones might interpret harshly. They can also shine as a room mic for drums.
Ribbon proponents claim that these mics hear more like the human ear, in terms of harmonic complexity and frequency response. One manufacturer, Royer, has built their business around making useful, durable ribbon designs that go beyond the technology from last century’s ribbon state-of-the-art. There are many ribbons that now feature in studio mic closets around the world.
Everything that’s typical about ribbon mics can be thrown out where the R-121 is concerned. This is a robust mic that can handle high sound pressure levels without blinking, but Royer’s flagship microphone is an interesting take on ribbons that takes this mic style out of the “boutique” neighborhood and brings them into the mainstream.
Another atypical ribbon mic, the M 160 features a hypercardioid polar pattern rather than the usual figure-8, but it’s become a typical addition to studio mic collections. Featuring a pair of ribbons, the M 160 shines on virtually stringed instrument, taming strident frequencies that many other mics exaggerate.
More like the classic ribbons mics of days past in both appearance and sound, the R84 takes on the old RCA “pill capsule” form factor that naturally imparts a vintage vibe. The R84 has the smooth response that’s not harsh in the upper frequencies, a classic characteristic of ribbon mics. Also like many quality ribbon mics, it’s flattering to virtually any sound source.
Though there are thousands of microphones on the market these days, they all rely on only a few core principles used to convert acoustic sound energy into electrical signals. These three main principles are:
Most of the microphones you’ll use for recording purposes fall into only two of these operating principles, but let’s look at each:
The word “dynamic” of course implies motion, and in the case of microphones, sound is generated by a moving element that’s suspended within a magnetic field. This is the same principle behind the most common way loudspeakers operate, only in reverse. In a weird bit of engineering trivia, you can use a speaker as a microphone, though it’s not very efficient electronically, or capable of authentic reproduction acoustically. For practical recording, the most common microphones are moving coil and ribbon designs.
In the case of capacitance mics – usually called condenser microphones in the recording world – sounds hitting the diaphragm cause changes in the amount of charge that can be stored between the diaphragm and a charged back plate. These changes create the electrical signal that’s then amplified and converted to an analog audio signal.
The capacitance principle uses a diaphragm, like many dynamic mics, but instead of attaching a coil to a diaphragm (a common dynamic mic construction), there’s a space between the diaphragm and a charged back plate in a condenser mic. A capacitor stores an electrical charge, in this case, the voltage supplied to (or by, in the case of electret condenser microphones) the back plate. Along with dynamic mics, condensers make up the bulk of the most common microphones used in audio.
Some of the earliest microphones used what’s called the piezoelectric effect. Some materials generate an electrical signal when subjected to mechanical stress. Certain crystals, in particular, create a tiny electrical signal when subjected to the pressure of sound vibrations.
Contact mics are often called pickups when used on acoustic guitars. Bridge or saddle pickups often use the piezoelectric effect modified by a preamp built into the guitar. Sometimes called “contact” microphones, the piezoelectric effect is not very strong, so airborne vibrations don’t create enough mechanical force to start the effect. However, a piezoelectric contact pickup, placed on the body of a violin or acoustic guitar, for example, can create a usable electrical signal. It’s not a particularly high-fidelity conversion.
There’s a type of mic sometimes called a “pressure zone microphone,” but more often known as a boundary mic these days. This is a specialty hybrid microphone that records sound in a hemisphere surrounding its placement. It’s a hybrid design that uses the capacitance principle, described above, rather than a true pressure-based response.
When you’re considering what microphone to use in a given application, the primary considerations are its operating principle – dynamic or condenser – and polar pattern, the shape in three-dimensional space that represents a mic’s sensitivity to sound.
That is, a mic is sensitive to sound based on its orientation to a sound source. There are three basic shapes, called polar patterns, as well as many ways these shapes can help you craft the sounds you want to record.
Meaning “heart-shaped,” cardioid polar patterns are most sensitive at the front of the mic and least sensitive behind the mic. Variations include super cardioid and hypercardioid, each with its own more exaggerated polar pattern. An example of a hypercardioid mic is the “shotgun” mic often used in broadcasting to reduce sounds from all directions except a narrow cone in front of the mic, often the same direction as the camera faces.
Also commonly called “figure-8,” bi-directional mics are equally sensitive on both front and back sides of the mic, with lowest sensitivity to both left and right sides. Because of their construction, ribbon microphones are naturally bi-directional, though this can be altered electronically. The figure-8 polar pattern sensitivity can be created electronically in a condenser microphone.
Equally sensitive to sounds from all directions. Omni mics often provide the most accurate sound reproduction, since this polar pattern is naturally free of something called the Bass Proximity Effect. This effect exaggerates the low frequency sensitivity of directional microphones, the closer they’re placed to a sound source.
Polar patterns aren’t directly connected to a mic’s operating principle, except for ribbon mics, which are naturally figure-8. Cardioid patterns are, by far, the most common polar pattern. This pattern captures sound best in front of the mic, making it useful for isolation in the studio and feedback rejection in live audio applications.
Some mics, most often condensers, can have more than one polar pattern, either through interchangeable diaphragm capsules or some sort of switching system. Multiple polar patterns can stretch a single mic’s applications, making them handy for a home studio without a large closet of mics to choose from.