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Studio Microphone Topics:
» Types of microphones
» How to read a microphone frequency chart
» Understanding microphone polar patterns
» Understanding microphone diaphragm sizes
Treating your signal path to the right Studio Microphone is important to attaining the sound your music calls for. This Sweetwater Buying Guide includes information that
can help you choose a Studio Microphone for your needs. Since there's so
much
to
consider when purchasing a Studio Microphone, don't hesitate to call 1-800-222-4700 for
more information.
Types of microphones
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What's a USB Microphone?
Probably one of the hottest developments in recent microphone technology has been the USB mic. Yet it's actually a fairly simple item to describe. 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. That makes mobile digital recording as easy as plugging in the mic, launching your DAW software, and hitting "record!"
Click here to view USB Mics
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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. One example of a highly popular condenser microphone is Neumann’s U87, shown here.
Click here to browse Studio Condenser Mics
Click here to browse Live Sound Condenser Mics
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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. One example of a highly popular dynamic microphone is Shure’s hand held SM58, shown here.
Click here to browse Studio Dynamic Mics
Click here to browse Live Sound Dynamic Mics |
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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. One example of a highly popular ribbon microphone is Royer’s R121, shown here.
Click here to browse Ribbon Mics
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How to read a microphone frequency chart
A microphone’s Frequency Chart can tell you a lot about which situations are appropriate for a given microphone and which situations are not. In theory, Frequency Charts are generated at the factory by testing the microphones in an anechoic chamber. An anechoic chamber is a specially constructed room just for audio testing. The idea here is to create a controlled atmosphere where each microphone can be tested equally, so the room is completely dead, without any form of sound reflection. Generally, a speaker is set up in front of the microphone that is being tested and pink noise is played (pink noise is all frequencies with equal energy in every octave). The microphone is routed into a spectrum analyzer that measures the output and a Frequency Response Chart is produced. The chart is usually over the 20 Hz to 20 kHz range, which is the range of human hearing.
So, how do you read it? The horizontal numbers in a Microphone Frequency Chart represent frequencies (again, usually over the 20 Hz to 20 kHz range) and the vertical numbers represents relative responses in dB (Decibels). As you look at a Frequency Chart, you can tell how a given microphone performs at certain frequencies. How is this information helpful? Well, let’s look at the famous Shure SM57’s frequency chart:
 The frequency response of the SM57 makes it especially good for certain instruments such as a snare drum because the fundamental frequency of the snare resides in the 150Hz to 250Hz range – right where the SM57 Microphone Frequency Chart shows that the SM57 response is flat, or neutral. In other words, at this frequency, what you hear going into the microphone is what you will tend to hear coming out – nothing more, nothing less. The presence bump to the right of the chart is just where the frequency of the “snap” of the snare resides. In addition, its rolled off low end makes it great for de-accentuating the kick drum which is often very close in proximity. This combination is what most engineers are looking for in a great snare drum mic – the ability to capture the true sound of the snare, accentuate its snap and reject other instruments in close proximity.
Understanding microphone polar patterns
Cardioid
A microphone polar (pickup) pattern.
Characterized by strong sensitivity
to audio from the front of the mic,
good sensitivity on the sides (at 90
degrees, 6 dB less than the front),
and good rejection of sound from the
rear, the Cardioid pattern can almost
be visualized as a "heart-shaped" pattern
(hence its name). The ability to reject
sound from the rear makes Cardioid
patterns very useful in multi-miking
situations, and where it is not desirable
to capture a large amount of room ambience.
Popular in both studio and live use
(where rear rejection cuts down on
feedback and ambient noise), Cardioid
mics are used for a very high percentage
of microphone applications.Keep in
mind that like all non-omnidirectional
mics, Cardioid mics will exhibit pronounced
proximity effect.
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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
.
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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.
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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.
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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.
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Understanding microphone diaphragm sizes
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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 coloration 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. While there are many great Large Diaphragm microphones available, AKG’s C
414 B-XLS microphone (shown here) is one example. |
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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). While there are many great Medium Diaphragm microphones available, RODE’s NT3 microphone (shown here) is one example. |
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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. While there are many great Small Diaphragm microphones available, Neumann’s KM
184 microphone (shown here) is one example. |
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