Things to Consider when purchasing a Microphone:
TYPES OF MICROPHONES
What’s a USB Microphone?
A USB mic contains all the elements of a traditional microphone: capsule, diaphragm, etc. Where it differs from other microphones is its inclusion of two additional circuits: an onboard preamp and an analog-to-digital (A/D) converter. The preamp makes it unnecessary for the USB mic to be connected to a mixer or external mic preamp. The A/D converter changes the mic’s output from analog (voltage) to digital (data), so it can be plugged directly into a computer and read by recording software. Plug in your mic, launch your DAW and start recording.
Condenser Microphone
The condenser microphone is a very simple mechanical system, with almost no moving parts compared with other microphone designs. It is also one of the oldest microphone types, dating back to the early 1900’s. It is simply a thin stretched conductive diaphragm held close to a metal disk called a backplate. This arrangement basically produces a capacitor, and is given its electric charge by an external voltage source. This source is often phantom power, but in many cases condenser mics have dedicated power supply units. When sound pressure acts on the diaphragm it vibrates slightly in response to the waveform. This causes the capacitance to vary in a like manner, which causes a variance in its output voltage. This voltage variation is the signal output of the microphone. There are many different types of condenser microphones, but they are all based on these basic principles.
Dynamic Microphone
A dynamic mic is one in which audio signal is generated by the motion of a conductor within a magnetic field. In most dynamic mics, a very thin, light, diaphragm moves in response to sound pressure. The diaphragm’s motion causes a voice coil that is suspended in a magnetic field to move, generating a small electric current. Generally less expensive than condenser mics (although very high quality dynamics can be quite expensive), dynamics feature quite robust construction, can often handle very high SPLs (Sound Pressure Levels), and do not require an external power source to operate. Because of the mechanical nature of their operation, dynamic mics are commonly less sensitive to transients, and may not reproduce quite the high frequency “detail” other types of mics can produce. Dynamic mics are very common in live applications. In the studio, dynamics are often used to record electric guitars, drums and more.
Ribbon Microphone
A type of velocity microphone. A velocity microphone responds to the velocity of air molecules passing it rather than the Sound Pressure Level, which is what most other microphones respond to. In many cases this functional difference isn’t important, but it can certainly be an issue on a windy day. Very old ribbon mics could be destroyed from the air velocity created just by carrying them across a room; today’s ribbon mics can handle the rigors of daily studio use. A ribbon mic works by loosely suspending a small element (usually a corrugated strip of metal) in a strong magnetic field. This “ribbon” is moved by the action of air molecules and when it moves it cuts across the magnetic lines of flux causing a signal to be generated. Naturally ribbon mics have a figure 8 pick up pattern. You can think of it like a window blind; it is easily moved by wind blowing at it, but usually doesn’t move when wind blows across it from left to right. Ribbon mics were the first commercially successful directional microphones.
MICROPHONE DIAPHRAGM SIZES
Large Diaphragm
Any microphone with a diaphragm larger than (and potentially including) 3/4″ is considered to be a Large Diaphragm microphone. In general, Large Diaphragm microphones tend to have a “big” sound that engineers find especially pleasing where a little more character might be advantageous, such as is the case with most vocals. Large diaphragms are generally more sensitive than small diaphragm or medium diaphragm mics because of the increased surface area. A common myth is that large diaphragm mics capture more low frequencies than small diaphragm mics. Sometimes their colouration may make it sound like this is the case, but a properly designed small diaphragm mic is more likely to be accurate throughout a wide range of frequencies, whereas the coloration of a large diaphragm mic can tend to enhance certain desirable characteristics in a sound, which sometimes amounts to more apparent bass or low end.
Medium Diaphragm
The definition of Medium Diaphragm is a potentially controversial subject. Historically there have been large diaphragm and small diaphragm mics, but more recently the medium size has begun carving out its own category, though not everyone agrees on the precise upper and lower limits. Most professionals and manufacturers agree that any microphone with a diaphragm near 5/8″ to 3/4″ can be characterized as a Medium Diaphragm microphone. Generally speaking, Medium Diaphragm microphones tend to do a good job of accurately catching transients and high frequency content (as a small diaphragm would) while delivering a slightly fuller, round and potentially warmer sound (as a large diaphragm might).
Small Diaphragm
While there are no final standards regarding a diaphragm size that defines Small Diaphragm, most professionals and manufacturers agree that any diaphragm smaller than 5/8″ would be considered a Small Diaphragm. Generally speaking, Small Diaphragm microphones tend to do a good job of capturing high frequency content and transients. They will tend to have a bit more “air” to their sound and often have less coloration than medium or large diaphragm microphones. Most of this is due to the reduced mass of the smaller diaphragm, which allows it to more closely follow any air disturbances it is subjected to.
UNDERSTANDING MICROPHONE POLAR PATTERNS
Supercardioid
A polar pattern name used to describe the pickup pattern of some microphones. The Supercardioid pattern is very similar to, and often confused with, the Hypercardioid pattern. The Supercardioid pattern is slightly less directional than the Hypercardioid pattern, but the rear lobe of sensitivity is also much smaller in the Supercardioid.
Hypercardioid
A polar pattern name typically used to describe microphone pick up characteristics. Hypercardioid patterns are similar to Cardioid and Supercardioid patterns in that the primary sensitivity is in the front of the microphone. They differ, however, in that the point of least sensitivity is at the 150 – 160 and 200 – 210 degree positions (as opposed to directly behind the microphone in a Cardioid pattern). Hypercardioid microphones are thus considered even more directional than Cardioid and Supercardioid microphones. Hypercardioid microphones are frequently used in situations where maximum isolation is desired between sound sources.
Omnidirectional
Literally, from all directions. In audio, microphones are said to be omnidirectional if they can detect sound equally from all directions. An Omnidirectional microphone will not exhibit a pronounced proximity effect.
Figure-8
A microphone polar pattern in which the mic is (nearly) equally sensitive to sounds picked up from front and back, but not sensitive to sounds on the sides. This produces a pattern that looks like a figure 8 on paper, where the microphone is at the point of crossover on the 8. The pattern is also known as bi-directional.