Microphones and Their Uses

The Art of Home Recording
The Art of Home Recording - Microphones and Their Uses
Photos: Jerry Monkman.

With such incredibly handy, high-resolution home-recording facilities available to the guitarist today, it can often be too easy to forget the basics in recording technique and gear usage that are so important to obtaining master-quality recordings. Or, it can be easy to think you don’t need to acquire them in the first place; power up the system, fire up the DAW, and you’re tracking in far-better-than-CD-quality in seconds. But, that recording is still only as good as what you put into it, so the “junk in/junk out” credo applies more aptly to home recording than to any other function of the musical arts.

After covering the basics of home-studio setup in the previous (and first) installment of this series, this time, we’ll dig into types and uses of the most essential piece of gear outside the recording system itself – the microphone (mic). Also read the third installment, Recording Electric Guitars.

Rather than simply saying, “Here’s a mic, stick it in front of whatever you’re making noise with,” the basic microphone types and their uses warrant a detailed look. Different mics perform quite differently, and as a result have very different applications within the studio, so understanding which mic to point at what (and when) constitutes a major part of any home recordist’s studio craft. Variations on specific uses and more in-depth mic technique will be covered in subsequent installments, but this issue will get you familiar with the range of mics that you might want to have at your disposal, and give you a thorough grounding on the best application of each. For now, think of the mic as the “sound paintbrush”; you might dip it in a range of different colors, but the thickness, texture, and character of that mic will imprint its character on whatever sound it transmits to your recording.

Make no mistake, though; if you only have one mic and no budget to add another in the near future, don’t let that stop you from capturing expressive recordings right now. This series is, first and foremost, about working with what you’ve got, but it is important to know what works best for the job when you have options. The “best” mic for a loud guitar cab, a kick drum, a subtle vocal part, a snare, and an acoustic guitar will be different each time, even if one mic – a Shure SM57, for example – might do okay at all of them.

Microphone Types

Dynamic Mics
Think of the dynamic mic as functioning similarly to a standard guitar speaker, but in reverse (they’re sometimes called “moving coil microphones” because of the way they work). Whereas the signal from an amplifier moves the voice coil mounted in a speaker’s magnet, causing it, in turn, to move the speaker cone and produce sound, a dynamic microphone does its thing when sound hitting the diaphragm moves a coil wound around a magnet, causing it to generate an electrical signal. There is no electrical circuit within a dynamic mic, and no electricity is applied to it to enable it to function – it is an entirely passive device containing just the diaphragm, a moving coil, and a magnet.

The dynamic mic’s simplicity (and lack of active electronic components) helps make it the most rugged breed of microphone. These qualities also make it more affordable to produce than other types of mics, and therefore cheaper to buy. Of course, “budget” versions of mics of all types are relatively cheaper today than in years past thanks to affordable Asian imports that mimic the basic designs of more complex Western mics of yore, but the dynamic mic remains king of the “rugged and affordable” castle. As such, they are often the choice for live/stage use for a wide range of applications, but they do many jobs well in the studio, too.

The Art of Home Recording - Microphones and Their Uses
Dynamic mics, like this Shure SM57, excel at capturing loud sounds close, like snare drums, kick drums, and guitar amps.

The dynamic mic’s ruggedness of build also translates to a certain ruggedness of sound. It isn’t as sensitive as an active condenser mic in regard to fidelity or output level, and lacks high-end detail in particular. That said, many good dynamic mics can still capture more than enough high-end detail for plenty of applications (it all depends how much you want, right?) and its sturdiness means it can take more punishment from loud sound sources, too, without distorting or, even worse, blowing out entirely. Though there are a few exceptions, dynamic mics are therefore the common choice for loud guitar amps, snares, and kick drums; for relatively close miking of loud brass instruments like trumpets and trombones, and so forth. The other side of the coin is that dynamics often lack the sensitivity to handle quieter sound sources like acoustic guitars, and by the time you boost them enough to do so (through whatever form of mic preamp), you risk introducing too much noise to make them viable for the application.

Since they are designed to take the punishment induced by close-miking applications, many dynamic mics lose a lot of detail when used at a distance from the sound source. Dynamic mics that are designed to be sung very close to for live use, for example, might suffer dramatic decreases in output at just three or four inches from a singer’s lips. Used on a loud enough sound source, however – a drum or a loud amp – most will give plenty of signal, and some dynamic mics can still be used, in a pinch, for drum overheads, guitar-amp room miking, and other more-distant applications where the source is pushing enough air to still be heard. Another inherent “drawback” of many dynamic mics is that these traits convene to give them specific characteristics, or what is often called a “colored” response, as opposed to an even/balanced response across the frequency range. Once understood, these can be used to your advantage in some situations; for this reason, a Shure SM57 with pronounced midrange has become a classic for recording punchy electric guitars.

Some of the most-classic (and popular) dynamic mics are made by Shure, AKG, Electro-Voice, Sennheiser, and Beyerdynamic. Purchased new, they will range from $100 (street) for a Shure SM57 (a classic for close-miking guitar amps and snares), to $400 for a Sennheiser 421 (drums, bass, guitar amps) or an Electro-Voice RE20 (kick drum, guitar amps). Fortunately, their robustness means they can be good buys on the used market; if your budget doesn’t stretch to that, several sturdy and decent-sounding Asian-made mics based on many of these classic designs will give reasonable service for a lot less money – even though, as with so many things in the recording realm, the old adage “you get what you pay for” applies consistently.

Condenser Mics
Also known as “capacitor mics” because of one type of internal component that helps them function, condenser mics include active electronic circuitry, and therefore need to have some kind of voltage applied to them in order to “hear” the sound source and produce a signal. The use of active circuitry allows a thinner, lighter diaphragm (which is part of an internal structure called a “capsule”), which moves more easily when hit by sound waves, and is therefore significantly more sensitive than the average dynamic mic. All of this translates to greater fidelity, a lot of detail in the sound, often a more-balanced frequency response, and a strong output signal.

This sensitive performance also means a degree of sensitivity is required in regard to their handling and use. Condenser mics aren’t usually positioned extremely close to loud sound sources, other than those designed specifically to enable such use, and doing so can result in distortion (or even damage) when the diaphragm is moved too vigorously. Some condenser mics are designed to be used close to guitar amps and drums, but most will be placed at least a foot back from such sound sources, or even more. Condenser mics used as drum overheads, for example, are likely to be placed four feet or more above drum heads and cymbals (which also keeps them out of whacking range). They can even yield some useful and interesting results when placed several feet back from a guitar amp or other loud instrument to be used as room or “ambient” mics, often blended with a second close mic.

The Art of Home Recording - Microphones and Their Uses
Condenser mics can reproduce great detail and excel at capturing nuanced acoustic instruments, as with the Audio-Technica AT4033, used here on piano.

The bonus of this increased sensitivity is, of course, that condensers are great for use on softer acoustic instruments, and voice, and they pick up nuances that most dynamic mics will miss, high-end detail in particular. Condensers are usually the mics of choice on acoustic guitars and other stringed instruments, piano, and vocals. Also, any effort to record a large ensemble in stereo in a “live” situation – or even just a band in a studio room – will usually involve a pair of condensers, rather than dynamic mics (using a range of stereo recording techniques that will be discussed in future installments).

There are a number of types of condenser mics. The two most common are differentiated by those that contain a vacuum tube and those that use solid-state circuitry. Tube mics, which are less common but still plentiful, generally require an external power supply to deliver the higher voltage levels that the tube runs on. Solidstate mics are usually powered by the 48-volt “phantom power” that many mixers, mic preamps, and interfaces supply through a standard XLR cable. Tube mics used to be universally more expensive, though as with all mic types, prices have come down considerably in recent years, with Asian-made tube mics from companies such as MXL and Behringer bringing them in at street prices under $200. The same trend has delivered solidstate condensers at the kinds of pocket-friendly prices one would have paid for a budget dynamic mic 20 years ago.

Classic condenser mics have been made by Neumann, AKG, Sony, Shure, and Audio-Technica, though the field has opened in recent years thanks to affordable new options that emulate some of these designs. Again, you get what you pay for, and if your budget can stretch to one or two good “starter pro-level” condensers from longstanding makers – an AKG C414, Neumann TLM 102, Audio-Technica AT4033 or similar, or even a lower-mid-priced option from Rode, Blue, Oktava, Sennheiser and others – your recordings are likely to benefit.

Beyond the type of circuit they carry, condensers can vary in several other ways. They are also split broadly between “large-diaphragm condenser” and “small-diaphragm condenser.” The former group includes the large, and particularly broad, mics you see in front of vocalists in many studio photos, mics such as the Neumann U87 and U47 or AKG C414 and C12. In addition to voice, they are also popular on pianos, stringed instruments, as room/distant mics on louder instruments, and drum overheads. Small-diaphragm condensers, as their name would imply, are able to be made in smaller packages, and take the form of the “pencil mics” like AKG’s C451 or the more affordable Rode NT5. These are also popularly used in stereo pairs as drum overheads, and on acoustic guitars and other stringed instruments, though less often on vocals.

Ribbon Mics
For years, ribbon mics were high-end products, and often forgotten altogether, but they have benefited from a resurgence in popularity since the early 2000s, thanks in part (once again) to the affordability of Asian makes and models. Before condenser mics, ribbon mics were the big boys in town for studio recording and even live use, and vintage versions from RCA, in particular, were the go-to through much of the jazz age.

Though generally considered a category of their own, ribbons really are dynamic mics by function, and are passive designs that produce signal through a similar electronic interaction to the one that makes a good old SM58 tick. The difference with the ribbon mic, though, is that in place of the thicker, heavier circular diaphragm and coil of the SM58, SM57, and their kind, it uses a long, narrow, and extremely thin “ribbon” of aluminum clamped tightly between the poles of a magnet, or two magnets, with a transformer coupled to it. In a sense, the ribbon performs as both a diaphragm and a transducer in one. As such, ribbon mics are less sensitive than condenser mics in terms of output level, though the topology of a good ribbon mic offers a certain depth, thickness, and “air” that can make it a great-sounding mic – one many consider very “real-sounding” – for many applications.

The Art of Home Recording - Microphones and Their Uses
Ribbon mics have made a major comeback for their warm, rich, in-the-room sound. Here, a Coles 4038 on a National-Resophonic Delphi.

The resurgence of the ribbon mic is due in large part to many recordists’ rediscovery of its benefits, especially in the age of digital recording, when any tool that inherently thickens and warms the sound of a track can be useful. A ribbon mic can make a guitar amp or drum kit playback sound more like it does in a room than almost any other mic, when a standard dynamic sounds too dull, or a condenser sounds to tinny and detailed. One bonus quirk of many types of ribbon mics is that their design, when mounted in the right enclosure, allows them to detect sound waves from the front and back of the ribbon. For this reason, many have a figure-8 pickup pattern (more on that below), which is part of what helps them to produce the great live, airy, “in-the-room” response for which they have become famous, while also opening them up to many clever applications.

There are several downsides to ribbon mics, but these can be worked with/around because they often exhibit a characteristic known as “proximity effect,” which puts a greater emphasis on low frequencies the closer you use the mic to the sound source (many mics of other types do this, too, but it tends to be more pronounced in ribbons). This means you need to keep them 12″ or more from the source to avoid the difficulties of downside number two – their low output. But, it’s something you would want to do anyway, in light of downside number three – their fragility. The low output of ribbon mics means they should be used with a quiet, high-gain preamp in order to achieve acceptable input levels without ramping up background noise. Such mic pres are not typically found in the built-in preamps of average low- to mid-level digital interfaces.

That fragility, by the way, can limit the use of a ribbon mic. Put an old-school ribbon too close to loud guitar-amp speaker, a snare drum, or kick drum, and you’ll stretch or damage it, and very likely ruin its thin aluminum ribbon. Some are so delicate you wouldn’t risk using them on anything but a low-watt amp. Also, if you so much as blow into it or even carry it too fast across the room without shielding the ribbon from the air pressure, the same damage is likely to occur. Likewise drop it, shout into it, hit it with a drumstick… you get the picture. Many do not like to have phantom power accidentally applied to them either (as happens when you forget to switch off your mixer or interface or mic pre’s phantom power switch when changing from a condenser mic to a ribbon mic). Handled carefully and with full awareness of their limitations, most good ribbon mics can last decades (and most can be re-ribboned when they don’t), but they do require more care than the average dynamic mic. Having said all that, several new ribbon-mic designs address some (or all) of the limitations.

Classic ribbon mics include RCA’s model 44 and model 77, perhaps best-known for appearing with singers Elvis Presley and Bing Crosby, as well as newsman Edward R. Murrow and talk-show host Johnny Carson. In the U.K., Coles has continued to manufacture the BBC-designed 4038 (originally made by STC), known for its use by everyone from The Beatles to Led Zeppelin. In Germany, great ribbons take the smaller forms of models like the Beyerdynamic M130, M160, M260, M500, and others.

The resurgent popularity of the ribbon mic has, however, has recently broadened the field in both pro-quality and budget-level options. Royer arrived in the late ’90s as one of the first new high-quality ribbon-mic makers, and its range has expanded from the R-121, long considered a modern classic and a great guitar-amp mic, in particular, to a lineup of models to suit all kinds of requirements. And, naturally, we can thank Asian production once again for an influx of stunningly cheap new ribbon mics, which can display random and inconsistent quality, but often sound surprisingly good. Shop for mics wearing the brands Nady, MXL, Cascade, Alctron, KAM, ART and several others – some of which (as their similar shapes might tell you) are actually made in the same factory – then, if you’re the DIY type, Google mods that can make these even better-sounding.

Microphone Pick-Up Patterns

Many of the old-school skills you’ll want in a new-school studio involve correct mic usage. Mics are designed along several parameters, and a big part of that is the way in which they reject sound from certain angles – a factor determined by their pick-up pattern (also called “polar pattern”). To the inexperienced recordist, a mic’s inability to adequately “hear” sounds coming from certain specific directions might outwardly seem a shortcoming, but this is actually an intentional aspect of any good microphone’s design, and one that an experienced engineer uses to their advantage. The fact that a mic might be less sensitive to sounds coming from behind it or from the sides, for example, means you can position it so that unwanted sounds from other instruments are all happening in that region, and are less likely to bleed into the instrument that you are intending to record with it.

The Art of Home Recording - Microphones and Their Uses

Cardioid Sometimes also called “unidirectional,” which is a more self-explanatory name for them, cardioid mics primarily pick up sound coming from in front of the capsule. As the sound source moves from directly in front of the capsule to either side, it will be detected at declining degrees and usually with some change in frequency response, until it is far enough off axis and is dropped entirely. In addition to providing a good recording tool, the cardioid pattern is popular with live sound, since its rejection pattern can minimize feedback. Examples of popular mics with this pattern are the Shure SM57, SM58, and Beta 52; Electro-Voice RE20; AKG C451 and D112, and several others. Many big condenser mics have switchable patterns, which will include a cardioid setting.

The Art of Home Recording - Microphones and Their Uses

Hyper Cardioid Mics with this pattern have a slightly tighter pick-up zone in front of the capsule with excellent side rejection, but also some detection of low-frequency sounds from directly behind the body of the mic. The relatively narrower pick-up pattern makes such mics less likely choices for singers who might move off axis while performing, and thereby change the output level of their vocal in the process, but good for fixed instruments like guitar amps and drums, as applicable. The Beyerdynamic M160 and M201, Rode NT3, and Audix OM2 are all hyper cardioid.

The Art of Home Recording - Microphones and Their Uses

Figure 8 As its name implies, the figure-8 mic (also called “bi-directional”) hears sounds from two different and opposing directions. While this might at first seem an undesirable characteristic, this pattern can be used to your advantage in several recording situations. Even when used as you would a cardioid mic, with the “front” of a figure-8 mic aimed at your sound source, this pick-up pattern can capture more “air” and room sound into the recording of many instruments, for a more-natural feel, while offering good rejection of sounds from the sides of the mic. It can also be used to record two sounds or singers at one time, or to capture a left-and-right image for a stereo recording when used in a mid-side (M-S) stereo configuration (as described in a future installment). Though figure-8 mics imply an equal pick-up of sounds from both sides of the capsule, many actually have slightly unequal pick-up patterns, and it’s best to check a mic’s spec sheet to discern. Figure-8 mics tend to be condenser or ribbon types, examples of which include the Royer R121, Coles 4038, and Schoeps CCM8. Some others, like AKG’s hardworking C414 condenser, have switchable pick-up patterns that include a figure-8 setting.

The Art of Home Recording - Microphones and Their Uses

Omni Clearly self-explanatory, an omni mic picks up sound from all directions. Popular for live-speech and broadcast applications, where it’s useful to pick up speakers positioned in different parts of the soundstage, an omni mic’s usage is more limited in the studio, and almost nil in live sound, where it might pose a feedback nightmare. In the studio, engineers have often used classic omni mics to record acoustic instruments in beneficial spaces, where the nuance of the room is captured, as well as to record drums (a great tool in a minimal drum-miking set-up), piano, or even electric guitar amps where you want a lot of room sound in the track. The AKG C414 includes an omni setting, as do the multi-pattern Shure KSM44 and CAD GXL-3000, while a list of dedicated omni mics includes the Neumann M150 and Microtech Gefell M296.

In the next installment, we’ll discuss recording electric guitars, and finally start using a lot of this stuff!

In addition to being VG’s resident amp historian, Dave Hunter is the author of several books on gear and technique, including The Home Recording Handbook (Backbeat Books, 2012), which covers in further detail many of the techniques discussed in this series.

This article originally appeared in VG November 2014 issue. All copyrights are by the author and Vintage Guitar magazine. Unauthorized replication or use is strictly prohibited.