XO Wave: A Super Quick Tour of Microphone Types

Omni-directional
Cardioid
Hyper-Cardioid
Figure-8

Microphones come in a variety of types. They can be directional or non-directional, large or small diaphragm, dynamic or condenser, etc. In addition, each make and model has its own character. A few simple rules will help you sort out the mess:

Condenser vs. Dynamic: Condenser microphones are generally more sensitive, with better frequency and transient response (which means they are more accurate), and more expensive. Dynamic microphones, on the other hand, can generally sustain louder sounds before they distort, are cheaper, and often impart their own distinctive character, or "color", to the sound they record. In addition, condenser mikes generally need to be powered from an external source -- often "phantom power" supplied by the microphone pre-amp.

Pickup Patterns: Microphones come with different "pickup patterns", some of the most common of which are shown on the left. Pickup patterns specify how sensitive a mike is to sounds coming from different directions. For example, non-directional, or "omni-directional" microphones, which pick up sound evenly in all directions, have pickup patterns that look like circles. Directional mikes, which are more sensitive to sounds coming from some directions than others, have other shapes. For example, "cardioid" mikes (so called because their pickup patterns resemble heart shapes) are more sensitive to sounds coming from the front than the back. Some mikes have a "Figure-8" pattern, meaning that they pick up sounds from the front and back, but not the sides. Of course, no mike is perfect, so whatever pattern the manufacturer claims a mike has, remember that pick-up patterns actually vary with frequency, meaning, for example, that most mikes are less directional at low frequencies and more directional at high frequencies. Moreover, mikes generally add more "color", or mild distortion, to sounds which come from off-axis, which often makes sources from either side of the mike sound less natural.

Diaphragm size: The diaphragm of a microphone is the part of the mike that converts vibrations in the air to electrical signals. The vast majority of mikes use either large or small diaphragms, although there are a few that use medium sized diaphragms. Generally speaking, large diaphragm mikes have more "color" off axis, are more sensitive, and are less tolerant of loud sounds. Small diaphragm mikes are generally more accurate off axis, and are less sensitive. In addition, most large diaphragm microphones have a property called "proximity effect", which means that as they get closer to the sound source, the amount of bass increases faster than other frequencies.

Which mike should you use?

Selecting an appropriate mike to use for a particular purpose can be tricky business. Recent advances in technology, while making microphones cheaper, has flooded the market with microphones. This is great for the home recording engineer who knows what she wants, but it can make the decision about which mike to buy even harder than it once was. Here are some tips on microphone selection, with an emphasis on the microphones that are most commonly used in the industry. When buying mikes, keep in mind that you can usually get them for much cheaper than their list price, which is what we cite here.

Vocals: Remember that vocals are the most important track in most contemporary music, so this is where you'll probably want to spend as much cash as you can. Generally speaking, vocals demand the sensitivity and response of a large diaphragm condenser mike. If you can afford them, the Neumann U-87 (approx $3,800) and the AKG 414 (approx $1,080) are fantastic, world-class microphones, which have been industry standards for years. For those without such deep pockets, both companies make less expensive microphones as well. For example, AKG's C 3000 B ($565) is an excellent stand-in for the 414, and the Neumann TLM series microphones are excellent as well, though still on the expensive side ($1,000-2,000). The ElectroVoice RE-20 ($750), and newer RE-27 ($864) are great dynamic mikes for vocals. The RE-20/27 are a bit unique because they are so-called "Variable-D" microphones, meaning they have no proximity effect. Because of this, and their smooth response, it is a great choice for many vocalists -- especially those that like to "work the mike". Even less expensive mikes that are great for vocals are made by Rode, Audio Technica, ElectroVoice and others. Whatever mike you buy -- especially if you are breaking the bank for it -- be sure to listen to it first, since it may not be right for what you are doing.

Other Rock/Pop Instruments: For guitar amps, snare drums and lots more, no mike can even come close to the popularity of the Sure SM 57 ($158). This mike is durable, cheap (by microphone standards) and sounds great. Its frequency response has a mid-range peak which gives instruments recorded with it a little more presence (people refer to this type of response as having a "presence-peak"). This mike has also been used on a number of vocal tracks in a number of genres including rock, hip-hop, and rap. Because of its versatility and low cost, many recording engineers refer to this as their "desert island" mike, but there are a lot of other mikes out there. Sure's other great mikes include SM 58 ($188) and their Beta series mikes ($200-$500). I've got a Sure 55 SH II ($285), which sounds great and has a classic look that singers and guitarists love, although I've heard that the quality of this particular model can vary. For low-frequency instruments, such as bass amps and kick drums, the Sennheiser MD421 ($510) is a classic, but pretty much any dynamic mike with good low frequency response which can sustain loud volumes will work (the 421 is also great on horns). For capturing the sounds of cymbals and other percussion, it's great to have a pair of high quality mikes above the drum kit (called "overheads"). I have seen everything from Audio Technica shotgun microphones to Earthworks Omni-directional condensers used for this purpose, though a stereo mike, such as the Audio-Technica AT822 ($419), can also be a great choice, and they are very easy to setup.

Acoustic Instruments: If you are trying to create an accurate recording of an acoustic instrument, go for a high quality, small diaphragm condenser mike. Mikes by B&K and DPA (>$5,000) rule this class, but are beyond the price range of most recording engineers. Cheaper alternatives are made by Earthworks, such as the TC-30K ($1,890.00/pr) or QTC40 ($2,500.00/pr), and Sure, such as the SM 81 ($592). Large diaphragm condensers work well for this, too, but you have to be careful about added "proximity effect" and "off-axis coloration". In my opinion, a dynamic mike simply cannot compete with a quality condenser for acoustic instruments, but many people swear by their dynamics, using mikes such as the Beyerdynamic M201 ($239) and Sennheiser MD441 ($895).

Piano: There are as many ways of miking pianos as there are engineers, but there are a few things that many engineers do. For example, if you've got a nice sounding room and you want to hear some natural reverb, many engineers would place a matched, stereo pair of small diaphragm condenser mikes a few feet from the piano, which is also a great technique for other acoustic instruments. For less reverb, you can close-mike the piano. When close-miking pianos (and indeed most instruments) there is no need to use matched microphones. For example, it is common to use a dynamic mike for the bass strings and a condenser for the treble.

Other Situations: Once you've got a few good dynamic mikes, a pair of high quality, small diaphragm condensers and a nice large diaphragm condenser, you should be able to handle just about any instrument you want to record. There are other mikes out there, such as ribbon mikes, shotgun and so on, but you probably won't need these to get started recording music.

-- Bjorn Roche